Water Quality Basics for The Land Use Commissioner

Share Print       Smaller Larger

1. INTRODUCTION

This report was originally prepared as an educational project to assist volunteer members of local planning and zoning commissions. The goal was to provide them with a basic water resource primer tailored to this part of Connecticut, for use as a technical aid in reviewing applications and conducting planning activities. While originally prepared in 1986, this text remains relevant in addressing the vital issue of local water resource protection.   

The water resources of the Housatonic Valley Planning Region are derived from precipitation, both that which falls locally and that which falls elsewhere and flows in via surface watercourses and groundwater. Rail or melting snow may run directly over the land into watercourses, or again in a down slope spring, wetland, stream, or other surface water body.

The quality of the water as it moves through this portion of its natural cycle will depend to a great extent on the types of materials with which it comes in contact. In addition, man may interrupt the natural flow patterns of the water, diverting it for residential, industrial or other purposes, and possibly returning it to the natural system via septic systems or other means.

In addition to the readily observable surface waters, the Region‰s waters can also be found in bedrock fractures, surficial geologic deposits, and soil. An overview of each of these sources of water is presented herein.

 

2. SURFACE WATER

Much of the Region is characterized by ridges and valleys. These features have given rise to the creation of a variety of lakes, ponds, rivers, and streams. The most prominent surface water resource in the Region is Candlewood Lake, a man-made body of water which lies mostly in New Fairfield but also occupies portions of Danbury, Brookfield, New Milford and Sherman. Other sizable lakes in the Region include Ball Pond, Squantz Pond, Mamanasco Lake, Taunton Pond, Lake Kenosia, and Lakes Lillinonah and Zoar.

Three major river systems traverse the Region, the largest one being the Housatonic which flows southward through New Milford and then adjacent to Bridgewater, Brookfield and Newtown. It is joined in New Milford by the second largest watercourse, the Still River, which flows easterly through Danbury and then northerly through Brookfield toward its confluence with the Housatonic. The third most significant river is the Norwalk which has its headwaters in the Great Swamp of Ridgefield and flows southerly into Wilton.

The chemical quality of the Region‰s surface waters under natural conditions is generally good. In contrast to groundwater, the surface waters in the Region are subject to good mixing through wave action and turbulent flow. This factor is significant when considering the dilution potential of surface water as compared to groundwater. Contaminants will generally become diluted in surface water much more quickly than in groundwater. In addition, exposure to sunlight and air serves to dissipate many chemicals from surface waters, whereas groundwater simply stores them.

As a general rule, surface waters are also less mineralized than groundwater. The reason for this is that the quantities and kinds of dissolved minerals carried by water depend chiefly on the types of rocks and soils with which the water comes into contact. Because groundwater is in much longer contact with rocks and soils, it usually contains more dissolved minerals than the water of streams or lakes. Surface waters can nevertheless be plagued by a variety of natural and man-made impurities.

 

3. GROUNDWATER

A. GROUNDWATER - WATER IN BEDROCK FRACTURES. The bedrock of the Region consists primarily of metamorphic and igneous crystalline rocks such as gneiss, schist and granite. In some areas the bedrock is exposed in natural outcrops or in road cuts. Groundwater is transmitted in these hard rocks through fracture systems, or interconnected cracks, both horizontal and vertical, within several hundred feet of the surface.

The size and distribution of these water bearing fractures is irregular, and therefore well water yields will differ significantly from one site to another, but generally do not exceed 50 gallons per minute and frequently yield less than 5 gallons per minute.

Bedrock is the principal aquifer underlying more than 90% of the Region. It provides an important source of water for small individual uses such as private dwellings and also for some larger scale uses such as commercial, institutional and industrial facilities.

Bedrock in the Region consists of two general types, carbonate and non-carbonate. Carbonate bedrock, which consists entirely of marble in this Region, is composed predominantly of calcium and magnesium carbonate minerals. These minerals are more soluble than the minerals in non-carbonate rocks such as gneisses and schists. Typically, carbonate bedrock is more fractured and tends to yield more water than the non-carbonate bedrock. However, the water associated with this rock generally has significantly more dissolved solids and is quite hard due to the calcium and magnesium carbonates that are dissolved in it.

Carbonate bedrock also weathers more readily than does the more resistant gneiss and schist. As a result, the marble areas of the Region have over the ages tended to become river valleys, such as the Still River valley.

Bedrock exposures of marble are not common due to their ease of chemical weathering. Exposures, where they exist, are of considerable interest. The calcium rich soils resulting from the chemical weathering of marble outcrops provide restricted habitats for plants and animals which are not commonly found in other parts of Connecticut. 

Of particular significance is when these calcium rich soils are found in wetlands. Such wetlands are known as "calcareous" and their alkaline nature provides a unique habitat for a variety of rare and endangered species of flora and fauna. The Still River valley contains significant areas of calcareous wetland.

Non-carbonate bedrock, such as gneiss, schist and granite, is more diverse in origin and composition. It generally consists of compounds of the element silicon which are only slightly soluble under natural conditions. Outcrops of non carbonate bedrock are more common than the carbonate type due to slower weathering.

All bedrock types can transmit water through seams or fractures for relatively long distances, and provide little purification or attenuation of pollutants beyond that which occurred in the soil at the site of discharge. Cases of well contamination in bedrock aquifers have been discovered at considerable distances from suspected pollution sources. Control of pollutant sources is the only certain way to prevent damage to the quality of water in bedrock.

3B. GROUNDWATER - WATER IN TILL AND STRATIFIED DRIFT. The surficial geology of the Region, which consists of those earth materials above bedrock, consists of two types of deposits: till and stratified drift.

Till is the predominant surficial geologic material found in Connecticut. It was formed when glacial ice melted and directly deposited the rocky debris that was trapped on, in, or under the ice on the surface of the land. Till is composed of various mixtures of boulders, gravel, sand, silt, and clay particles, none of which are significantly sorted by water according to grain size.

Although thickness can vary from 0 to 200 feet, till in this Region is usually shallow, frequently from 10 to 50 feet deep. Its relatively low hydraulic conductivity limits wells to very modest yields, typically less than one gallon per minute in a shallow domestic well. Most such wells have long since been replaced by bedrock wells.

Stratified drift consists of sand and\or gravel that is commonly stratified into distinct layers. These materials were laid down by water emanating from or flowing within the melting glacier.

Most people can easily envision the appearance of a melting snow bank along a roadside on a sunny day late in February. As the resulting meltwater meanders through roadside sand, it induces a natural sorting and stratifying action such that particles of similar size are deposited together. Melting water from the last glacier accomplished this on a grand scale. The resulting water lain deposits formed the Region‰s stratified drift.

The Region‰s most productive aquifers are located in stratified drift. Where stratified drift has favorable hydraulic characteristics because of its coarse texture and saturated thickness, wells may yield relatively large volumes of water. Yields of 50 to 2,000 gallons of water per minute are typical. Because of their highly productive nature, the HVCEO has placed a major emphasis upon the need for special development regulations over stratified drift aquifers.

3C. GROUNDWATER- MOVEMENT OF CONTAMINANTS. Groundwater is subject to contamination from a variety of sources. Once a contaminated fluid seeps into the earth, its movement and concentration is governed by a number of factors. The direction of movement is controlled by gravity, the permeability of the soil, sediment fabric, bedding structure and the slope of the water table.

The initial movement of the fluid is generally downward until a layer of low permeability or the water table is reached. Lateral movement then develops in the shape of a plume. The rate of movement is controlled by the slope of the water table, permeability of the aquifer material and contaminant-material interaction. Concentration of the contaminant is also controlled by this interaction.

The interactions between the contaminant and geologic materials are complex and depend on the type of subsurface material present and the type of contaminant. For example, metals can be adsorbed on fine soil particles. Their movement through the soil can therefore be slower than the mass groundwater movement and concentrations may be lower than in the original contaminated fluid.

In the case of movement through fractured bedrock, however, little adsorption of metals occurs and movement may occur at the same rate as the groundwater mass. In addition to adsorption, other natural mechanisms which may help to prevent or retard the movement of contaminants below the soil layer include chemical precipitation, chemical degradation, volatization, and biological degradation.

Contaminants entering and moving through the groundwater system become a problem when they discharge into surface water bodies or water supply wells at concentrations and volumes sufficient to significantly degrade the existing water quality. In areas of changing land use, contaminated groundwater can become a problem when wells are drilled in or near the contaminated plumes, thus shifting the flow of the contaminated water to wells.

Such problems are compounded by the relatively slow movement of groundwater which implies very slow natural flushing or prolonged periods of cleanup. More on this below.

 

4. SOIL MOISTURE

Mineral soil particles are classified by size into sand, the largest, silt, and clay, the smallest. The size of a soil particle is directly related to its chemical reactivity. As the particle size decreases, the surface area per unit mass increases. The more surface area, the greater the number of negatively charged locations on the particle surface.

These negatively charged sites are called cation exchange sites. Cation exchange sites can hold positively charged elements or compounds to the soil particle surface. All things being equal, the more cation exchange sites available in the soil the greater is the soil‰s ability to filter out contaminants.

The largest soil particles are sand which are composed dominantly of the mineral quartz. Sand sizes range from 0.2 to 0.05 mm in diameter. Water flows quickly through these soils due to the large pore spaces between the sand grains. The quicker water flows through the soil, the less time there is for contaminants to be filtered out. Furthermore, the sand grains do not possess many cation exchange sites.

Silt ranges in size from 0.05 to 0.002 mm in diameter. Clay particles, along with organic matter, are the primary source of the soil‰s cation exchange sites. Not only do the exchange sites help to capture water borne contaminants, but the small pore spaces associated with the clay sized particles slow the flow of water through the soil. These are just two of the factors that are of prime importance in cleansing the water entering the soil.

Clay particles are less than 0.002 mm in diameter. Clay particles, along with organic matter, are the primary source of the soil‰s cation exchange sites. Not only do the exchange sites help to capture water borne contaminants, but the small pore spaces associated with the clay sized particles slow the flow of water through the soil. These are just two of the factors that are of prime importance in cleansing the water entering the soil.

Different soils can hold varying amounts of water depending on the dominant size of the soil. Some soils may store as much as 54,000 gallons of water per acre for each foot of soil depth. Soils of fine texture and high in organic matter will hold the most water. Sandy soils low in organic matter may store only one-half to one-third of this amount.

 

5. WATER QUALITY

5A. WATER QUALITY - INTRODUCTION. The purpose of this section is to identify the major physical characteristics of water and to highlight the major chemical and biological substances of concern with regard to water quality. To begin with, a brief review of some simple chemical terminology is in order.

The matter on earth consists of a limited number of basic substances called elements. Elements are substances that cannot be broken down into simpler substances by chemical reactions. There are 96 naturally occurring elements and some additional synthetic or man-made elements.

The 15 most abundant elements on land include, in order of abundance, oxygen, silicon, aluminum, iron, calcium, sodium, potassium, magnesium, titanium, hydrogen, phosphorus, manganese, fluorine, sulfur and carbon. 

The first nine of these elements make up 99% of the earth‰s crust. The elements carbon, hydrogen, oxygen, and nitrogen constitute all but one percent of the world‰s living creatures. Not surprisingly, discussion of water quality frequently makes mention of these abundant elements.

Elements consist of sub-units called atoms, which in turn consist of special combinations of protons, neutrons, and electrons. Electrons are negatively charged particles and principally responsible for chemical reactivity. Protons are positively charged particles and neutrons are neutral. Protons and neutrons are located in the center of the atom called its nucleus. Electrons reside in a designated space around the nucleus.

Ions are atoms or groups of atoms that carry a positive or negative electric charge as a result of having lost or gained one or more electrons. Many substances readily lose electrons in water and thus become ions.

Combinations of the earth‰s elements produce a wide variety of compounds. The fundamental unit of a compound is known as a molecule. Chemists traditionally refer to compounds containing the element carbon as organic compounds. All other compounds are called inorganic compounds. 

Organic compounds consist of naturally occurring plant and animal matter and synthetic organic chemicals manufactured in the laboratory. Organic chemicals outnumber all others by at least 12 to 1 due to the unique ability of carbon to unite with itself and other elements.

Crystalline inorganic compounds and elements are also known as minerals. Minerals may be metallic, such as iron or aluminum, or non-metallic, such as quartz and feldspar. Most of the earth‰s minerals are clustered into different types of rocks. Bedrock in the HVCEO area is usually composed of a combination of minerals. For example, the bedrock granite is commonly composed of the minerals quartz, feldspar, and mica.

Water is commonly referred to as the universal solvent. As such, it nearly always contains a variety of elements and compounds in solution. The amount of these constituents in any particular water sample is known as the total dissolved solid content. Common constituents of the water in the Region include silicon, iron, manganese, calcium, magnesium, sodium, potassium, and sulfate, accurately reflecting the earth‰s more abundant elements.

Most of the constituents found in water are measured in milligrams per liter (mg/1). This is also expressed, not quite so precisely, as parts per million (ppm). 

For comparison, one ppm is equivalent to one minute in the space of two years or one inch in 16 miles. Certain contaminants, such as mercury, require the even smaller measurement of micrograms per liter or ug/1. There are one thousand micrograms in one milligram. One microgram per liter is roughly equivalent to one part per billion or ppb. One ppb is equivalent to four drops of water in an Olympic sized swimming pool.

With this basic understanding of chemical terminology and measurement the major physical, chemical, and biological parameters of water quality can be explored.

Much of the discussion on the next three sections of the report was adapted from a report entitled "Water Resources Inventory of Connecticut, part 6, Upper Housatonic River Basin," by the U.S. Geological Survey, 1972; and "The Water Test User‰s Manual," by the water Test Corporation, 5^th Edition, 1985.

5B. WATER QUALITY - PHYSICAL CHARACTERISTICS. Hardness: Hardness is a property of water and generally refers to the capacity of water to precipitate soap from solution.

Hardness is primarily caused by the presence of calcium and magnesium ions in water. Iron and manganese also contribute to the hardness of water. Many people consider hardness to be a nuisance because larger amounts of soap are required to form washing suds. In addition, hardness causes soap to deposit an insoluble precipitate or scum on bathtubs. Hardness can also form scale in boilers, water heaters, radiators and pipes.

In the Housatonic Valley Region, hardness ranges widely. Water from the carbonate bedrock and stratified drift aquifers is hard to very hard. Most water from the non-carbonate bedrock aquifers is soft to moderately hard. Water having a hardness of more than 120mg/1 is commonly softened for domestic use.

Water is usually softened by an ion exchange water softener device. The water softener works by exchanging sodium ions for the magnesium and calcium ions as the water passes through it. By extracting the hardness ions from the water, softeners make the water more desirable for bathing, laundering, and other uses.

Color: Color in water may be of natural origin (mineral or organic) such as iron and manganese compounds, algae, weeds, and humus material. It may also be caused by inorganic or organic wastes from industry. The true color of water is considered to be only that attributable to substances in solution after the suspended material has been removed.

Water for domestic and some industrial uses should be free of perceptible color. Color in water is objectionable in food and beverage processing and many manufacturing processes. Results are usually expressed as units of color and not as mg/1.

Temperature: Temperature fluctuates widely in streams and shallow wells following seasonal climatic changes, but wells at depths of 30 to 60 feet remain within 2 or 3 degrees of mean annual air temperature which is 49.3F for the Greater Danbury Area. Disposal of water used for cooling or industrial processing causes local temperature abnormalities.

Temperature affects the usefulness of water for many purposes. For most uses, especially cooling, water of uniformly low temperatures is desired. A rise of a few degrees in the temperature of a stream may limit its capacity to support aquatic life. Warm water will carry less oxygen in solution than water at low temperatures, and a corrosive water will become more corrosive with increased temperatures. Temperature also influences the solubility of most minerals.

Dissolved Oxygen: This is the oxygen dissolved as a gas in water or other liquid and is usually expressed in mg/1, ppm or percent saturation. Adequate dissolved oxygen levels are necessary in waters to protect fish and other aquatic life and to prevent offensive odors. Low dissolved oxygen concentrations are generally due to excessive organic solids discharged as a result of inadequately treated waste. Excessive algal growths may cause vastly fluctuating dissolved oxygen levels.

Other factors such as temperature and water movement also have an impact on dissolved oxygen levels. Other factors such as temperature and water movement also have an impact on dissolved oxygen levels.

Sources of dissolved oxygen are natural aeration and photosynthesis by aquatic vegetation. In unpolluted waters, oxygen is usually present in amounts of 10 ppm or less. About 3 to 5 ppm is accepted as the lowest limit for support of fish life over a long period of time. According to DEP criteria, the dissolved oxygen in class AA, A and B surface waters should not be less than 5mg/1 at any time.

Biochemical oxygen demand (BOD) is a measure of the amount of oxygen required to remove waste organic matter from water through the process of decomposition by bacteria. The waste organic matter is stabilized or made unobjectionable through its decomposition by living bacterial organisms which need the oxygen in water to do their work. BOD therefore provides an index of the degree of organic pollution of water.

The effect of wastewater with a high BOD is to reduce the dissolved oxygen level in the receiving stream. DEP has established BOD limits for point sources of waste discharges to maintain an adequate level of dissolved oxygen to support aquatic life.

Turbidity: This is an optical property of water attributed to suspended or colloidal matter which inhibits light penetration. It may be caused by microorganisms or algae, suspended mineral substances including iron and manganese compounds, clay or silt, or fibers and other materials. It may result from natural processes or erosion or from the addition of domestic sewage or wastes from various industries.

Excessive turbidity is harmful or lethal to fish and other aquatic life. It is also very undesirable in water used by most industries, especially in process water. Turbidity can also produce undesirable recreational waters and modify water temperature. Results are expressed in standard units, not mg/1.

Ph: The pH of water is a measure of its acid or alkaline nature. Specially, it is an expression of the hydrogen ion concentration of the solution.

To determine if water is acidic or alkaline, a scale known as the pH scale is generally used. At pH 7 the solution is neutral. When there are more hydrogen ions (H+) than hydroxyl ions (OH-), the pH is less than 7 and the solution is acidic. When there are more hydroxyl ions, the pH is greater than 7 and the solution is alkaline. Thus, on the pH scale, lower numbers indicate a higher concentration of acid. The pH of most natural water ranges between 6 and 8.

Acidic water and excessively alkaline water corrode metals and can adversely affect aquatic life. PH can also affect the degree of toxicity of many chemicals by altering their solubility and hence their association with the hydrogen ions or other elements in water. For example, low pH conditions may cause the release of metals from sediment deposits into the water of a lake.

Acid rain, the common term describing the deposition of acidic compounds via rain, snow or fog, is characterized by water with a low pH. These acids are formed when nitrogen oxide or sulfur dioxide emissions, primarily from the combustion of fossil fuels, mix with moisture in the air and are converted to sulfuric and nitric acids. Natural rain has a pH range of 5 to 5.6, therefore, it is somewhat acidic. However, acid rain has a pH range of 4 to 4.6 which is ten times as acidic as natural rainfall. At the present time, rainfall in the Danbury Area has an average pH of 4.5 according to the Danbury Water Department.

According to the 14^th Annual Report (1983) of the National Council on Environmental Quality, "a pH of 5.5 has been shown to be stressful to certain sensitive cold-water game fish, and in a laboratory environment these fish cannot survive in water with a pH lower than 5.0. Fortunately, low pH rainfall does not automatically mean that the water in lakes and streams will become acidic. Most U.S. watersheds have a natural ability to buffer acidity. As the acid rainfall moves through the watershed, alkaline soils can neutralize the acidity. However, some watersheds particularly those at high altitudes with thin soil, have less ability to buffer deposited acids."

The ability of water to neutralize added acids or bases is called its buffering capacity. This buffering capacity is critical to the maintenance of health conditions in aquatic systems, particularly where they are stressed by pollution such as acid rain.

It should be noted that watersheds which are currently buffered by alkaline soils do not have an unlimited capacity to neutralize acid rain. It such watersheds continue to receive acid precipitation, the soils may eventually lose their buffering capacity, resulting in water quality impacts upon surface water and aquatic life. Such an occurrence could be sudden and irreversible.

Much certainty and disagreement exists in both the scientific and political communities as to the best approach for controlling acid rain. One thing is clear, its effect is being felt in the Housatonic Valley Region. According to the Danbury Water Department, after major storms the acidity of water in the City‰s reservoirs may increase from a neutral pH of 7 to a pH of between 5 and 6 - 100 to 200 times more acidic. Water Department staff readjust the acidity of the water by adding sodium hydroxide (an alkali) before it leaves the water treatment system.

Several states in the northeast are now attempting to neutralize the damage from acid rain to selected lakes by pouring tons of a powdered limestone slurry into the lakes. This technique has been used successfully for years in Scandinavia.

5C. WATER QUALITY - BIOLOGICAL IMPURITIES. In order to deal with water quality it is important to understand simplified definitions of "bacteria" and "virus". Bacteria are microscopic, unicellular plant cells which may occur as individual cells or in clumps. In size, bacteria are on the order of 1/25,000 of an inch. For reference, 250,000 bacteria could easily fit into the dot of this "i". Bacteria are also prolific - under the right conditions, one bacterium could produce a colony large enough to cover a football field in 24 hours.

Bacteria may be classified on the basis of their requirements for free atmospheric oxygen. Some bacteria require free oxygen and are termed aerobic (air living). Other bacteria cannot live in the presence of atmospheric oxygen and are called anaerobic. Bacteria are useful in the decomposition of dead plants and animals, and may also play a beneficial role in the decomposition of some types of contaminating agents.

Bacteria are dependent upon the proper temperature for life and reproduction. High temperature quickly kills bacteria. Bacteria may also be killed by the action of chemicals called disinfectants, such as chlorine.

Viruses are considered to be the smallest infectious agents capable of replicating themselves in living cells. They have a core of nucleic acid surrounded by a protein coat. Viruses are usually far smaller than bacteria and survive by invading other living cells including bacteria. They use the host cell and cause it to manufacture more viruses and eventually cause the death of the host cell. 

When viruses are not inhabiting living cells, they show none of the usual signs of life. Also, they have no ability to reproduce outside of a living host cell. The majority of these extremely small infectious particles fall within a size range of .02-.25 micrometer and can only be visualized directly with the aid of an electron microscope.

Although bacteria may serve positive functions as stated above, problems in water quality may arise from the introduction of disease producing bacteria and viruses through disposal of treated and untreated sewage or animal wastes. These pathogens may live for periods of days to months below the water table. In highly permeable materials, they may be transported hundreds of feet along groundwater flow paths. Such biological contamination may render the use of water unfit for human consumption or other domestic purposes.

The coliform group of bacteria has, as one of its prime habitats, the intestinal tract of humans. Therefore, the presence in water of members of this group is considered an indication of potential contamination.

The coliform bacteria themselves do not represent a significant health hazard, but because diseases such as infectious hepatitis, cholera, dysentery, and assorted other infections are transmitted by fecal contamination, the presence of coliform indicates the possibility of the presence of these disease - causing organisms. Due to this relationship, coliform bacteria have long been used as indicators of the sanitary quality of water. Results of coliform counts in local water bodies used for swimming are often reported in local newspapers.

Not all waterborne diseases come from bacteria and viruses. Larger organisms, such as amoebas and protozoans, can also cause water quality problems. The parasite Giardia is one example of a protozoan which can degrade water quality and foster the need for additional water treatment. Protozoans such as Giardia are resistant to the usual water treatment chemicals such as chlorine, and generally heating, distillation, or microfiltration are required for effective control.

5D. WATER QUALITY - INORGANIC CONSTITUENTS. Discussed below are several of the more common inorganic constituents found in the surface and groundwaters of the Housatonic Valley Region.

Silicon: This element is dissolved from practically all rocks and soils. It is usually found in small amounts ranging from 1 to 25 mg/1. Surface water usually has a smaller concentration than groundwater.

Because of its chemical reactivity, silicon does not occur in elemental forms in nature. In surface water, it is usually present as silica (Si02) or a silicate (silicon, oxygen, plus a metal). Silica can form hard scale in boilers, water heaters, and pipes but is of no particular health significance.

Iron: Iron occurs naturally in several materials, mainly in the form of oxides, carbonates, silicates, and sulfides. Decaying vegetation and iron objects in contact with water, sewage, landfill leachate and industrial waste are also major sources. Surface water in its natural state usually has less than 0.5 mg/1. Ground water generally has higher concentrations than surface water.

Iron in drinking water is a very common problem in the Housatonic Valley Region. Iron is soluble in groundwater due to the absence of oxygen and is not visible. However, on exposure to air, iron in water oxidizes to a reddish-brown precipitate and settles out as rust-like material. More than about 0.3 mg/1 iron stains laundry and bathroom fixtures, causes unpleasant odors and a metallic taste to the water, and favors the growth of iron bacteria.

Iron in water is also objectionable for food and textile processing and recent research has shown that high iron levels in food and beverages may present a health hazard. Most iron bearing waters can be satisfactorily treated for domestic use by aeration and/or filtration system.

Manganese: This silver-white metal is dissolved from many rocks and soils. It is often found associated with iron in natural waters but is not as common as iron. Surface water usually has less than 0.1 mg/. Ground water generally has higher concentrations than surface water. More than 0.2 mg/1 precipitates upon oxidation. Manganese has the same undesirable characteristics as iron but is more difficult to remove.

Calcium and Magnesium: These silver white metals are dissolved primarily from carbonate rocks. Groundwater in carbonate rocks may contain as much as 100 mg/1 calcium and 40 mg/1 magnesium. Surface water normally contains lower concentrations than groundwater.

Hardness and scale forming properties of water are caused by dissolved bicarbonates and sulfates of these elements. These are objectionable for bathing, laundering, electroplating and dyeing. Scale formation can present problems in steam boilers, water heaters, and pipes.

High levels of calcium and magnesium in drinking water are also considered to be of some concern from a public health standpoint. Water softeners can be employed to remove calcium and magnesium ions.

Sodium and Potassium: These silver white metals are also dissolved from practically all rocks and soils. Due to their great chemical reactivity, neither sodium or potassium occur in nature in their free state. Sewage, industrial wastes, and road salt are also major sources. Most home water softeners replace soluble, hardness-producing minerals with sodium and thus increase the amount of sodium present.

Since the concentration of potassium in water is usually low, sodium and potassium are often calculated together and reported as sodium. High levels of sodium and potassium in drinking waters are a concern with regard to public health.

Several health officials in the Region have recently expressed concern that sodium contamination of groundwater from water softeners and road salt could eventually render the water undrinkable. The concentration of sodium in class AA surface waters (existing or proposed drinking water supplies) should not exceed 20 mg/1 according to DEP‰s surface water classifications.

Fluoride: This chemical is dissolved from naturally occurring minerals. Concentrations as high as 6/1 mg/1 have been measured in Connecticut from naturally mineralized water. About 1.0 mg/1 of fluoride reduces the incidence of tooth decay in young children and is added to public water supplies by fluoridation. Larger amounts, above 2.4 mg/1, may however cause mottling of tooth enamel. Levels of fluoride above 6 to 8 mb/1 can cause skeletal fluorosis in humans, a disease which makes bones brittle. According to the U.S. Public Health Service, approximately 61% of the U.S. population is drinking fluoridated water.

Sulfur: This chemical is also dissolved from naturally occurring minerals in rocks and soils. It is generally present as sulfate (SO4) or sulfide (SO2) in surface waters. Sulfur compounds may also be dissolved in precipitation, and in sewage and industrial wastes.

Sulfates of calcium and magnesium cause permanent hardness and form hard scale in boilers and hot water pipes. Hydrogen sulfide is responsible for the "rotten egg" odor which may emanate from stagnant ponds or exposed mud during the summer months, or from under the ice in winter.

Most people can taste unpleasant sulfate concentrations at 300-400 mg/1. Chlorination, aeration, or filtration can be used to eliminate hydrogen sulfide from drinking water source.

Nitrogen: Like many elements, the compounds of nitrogen by far exceed the abundance of elemental nitrogen. Three common molecular forms of nitrogen are ammonia (NH3), nitrate nitrogen (NO3) and nitrite nitrogen (NO2). Ammonia in most waters is caused by the natural breakdown of animal and vegetable protein material by bacteria. When dissolved in water, ammonia will react with the water to form ammonium ions.

Nitrate is formed from the complete oxidation of ammonium by certain micro organisms in which nitrite is an intermediate product. In well oxygenated waters, nitrite is readily oxidized to nitrate. In addition to naturally decaying animal and vegetable matter, other major sources of nitrogen include sewage, industrial wastes, fertilizers, and the atmosphere.

While nitrogen is essential to practically all forms of life, all three forms of nitrogen are toxic to aquatic life when specific concentrations are reached in a waterbody. Nitrate nitrogen encourages the growth of algae and other organisms which produce undesirable tastes and odors in water. A concentration of 10 mg/1 of nitrate nitrogen has been shown to be dangerous to the health of infants. Generally, a concentration greater than 10 mg/1 of nitrate indicates pollution.

Ammonia exerts a negative impact upon surface waters in two ways. First, if the levels are high enough, ammonia can cause a direct toxicity to fish and aquatic life. Also, ammonia exerts an oxygen demand upon a receiving water consuming oxygen in the conversion of ammonia to nitrites and nitrates.

Methods available for the control of nitrogen in drinking waters include steam distillation and reverse osmosis. Activated carbon is not an effective medium for nitrogen removal.

Phosphorus: Phosphorus usually enters a waterbody from land runoff, domestic sewage, animal excreta, decaying vegetation, fertilizers, industrial processes, and detergents. Most phosphorus in surface waters is present as phosphate (PO4). Concentrations of phosphate in natural streams are generally low; in larger streams they occasionally exceed 1.0 mg/1.

Phosphate is an essential nutrient for free floating aquatic vegetation such as algae. Excess phosphate may encourage algal blooms and cause problems of odor, taste, and aesthetics.

Connecticut prohibits point source discharges of phosphorus which will raise the phosphorus concentration of the receiving surface waters to an amount in excess of 0,.03 mg/1.

Other: A wide variety of other inorganic chemicals exist which may have a significant impact on water quality. A few of the better known examples include asbestos, arsenic, and the heavy metals cadmium, chromium, lead, copper, zinc, and mercury. Even small quantities of these inorganic chemicals can contaminate drinking water and present a threat to public health. Methods available to remove trace amounts of many of these chemicals include distillation, ion exchange, reverse osmosis, and carbon filtration.

5E. WATER QUALITY - ORGANIC CONTAMINANTS. Of primary concern in water quality protection today are the synthetic organic chemicals and hydrocarbons. The Connecticut DEP recently released a report entitled "Protecting Connecticut‰s Groundwater" wherein these contaminants are described. Most of the text below represents excerpts from that report.

The term synthetic organic chemicals (SOC‰s) includes a large number of chemicals. Among these are the toxic and hazardous substances used as solvents in industries, homes and businesses, as well as pesticides used on lawns and agricultural fields. Hydrocarbons are compounds that contain atoms of carbon and hydrogen only. Hydrocarbons of concern are primarily liquid fuels, including gasoline, oil, and petroleum distillates used in manufacturing. Some components of these fuels, such as benzene, are extremely hazardous.

Some of the more common organic contaminants in addition to benzene are carbon tetrachloride, chloroform, dichlorobenzene, dichloroethane, dichloroethylene, dioxin, polychlorinated biphenyls, tetrachloroethylene, trichloroethane, trichloroethylene, and vinyl chloride.

Many industries and businesses use SOC‰s and hydrocarbons as part of their normal operation. Furniture strippers and dry cleaners depend heavily on chemical solvents as cleaning agents. Automobile repair shops, metal-working industries, and many small industries use solvents regularly to clean parts. Hospitals, laboratories, and even schools use these chemicals in their routine laboratory procedures. Problems can occur during the storage, use, transport and disposal of these chemicals.

Because of the recent ability to detect and measure even very low concentrations of these varied chemicals in water, synthetic organics and hydrocarbons are being found in a number of groundwater supplies across the state. These chemicals are often persistent, or slow to degrade.

Once discharged to the ground surface through spillage or purposeful dumping, some will evaporate, but most will enter the ground either by percolating through the soil down to the water table, or as dissolved contaminants carried to the water table by percolating rain and snow. Some contaminants will remain in the soil, where they will continue to leach into the groundwater, often for many years.

Precise health effects of long-term exposure to low levels of these numerous and highly-varied compounds are not known. Many, however, are suspected carcinogens. Drinking water standards have been established for only a handful of SOC‰s, but where they exist, maximum permissible health levels are often very low (less than 50 parts per billion, the equivalent of about one drop in a swimming pool). Because the "safe" concentrations are so low, spillage of even minute amounts can cause contamination problems. While health effects are largely unknown, the social and economic impacts that result from finding SOC‰s in a water supply are severe.

Many public and private wells have been contaminated in Connecticut due to SOC's and hydrocarbons. Several examples include cases in which a residential well was contaminated due to the use of a degreasing solvent in the owner's own septic tank. In other examples, industrial dumping caused contamination of public water supply wells serving thousands of users in Southington, and a gasoline leak in Brookfield polluted several private wells.

Treatment to remove most SOC's from contaminated supplies, either by aeration or filtration with carbon, is feasible although expensive. Units are available to treat individual faucets or household supplies and large systems are available to treat major public supplies. Professional advice should be sought in purchasing any system, since treatment effectiveness varies widely and since any treatment mechanism requires continuous maintenance.

It should also be noted that activated carbon is not effective in filtering out all organic molecules. Some varieties of volatile organics in particular are not well removed by carbon. For example, benzene, a component of gasoline, is a relatively small molecule not easily filtered by carbon.

 

6. SEPTIC SYSTEMS

The impact of septic disposal systems on water quality is a question raised with great frequency by members of local commissions. Septic systems can fail in the conventional sense which result in the surfacing of effluent in the immediate system area. Such failure can create serious public health and environmental problems. Septic systems can also fail when the amount of discharge overloads the soil/groundwater treatment system and causes degradation of water quality entirely below the surface of the ground.

The DEP has released an excellent document entitled "Septic System Manual" which can guide local land use officials on the technical aspects of the design and installation of on-site subsurface sense disposal systems. This section, largely adopted from that DEP report, is limited to a discussion of pollutants and their renovation potential.

 It should be noted that it is possible to perform pollutant-specific calculations for such parameters as nutrients and bacteria and these calculations are routinely part of the DEP permit process for large septic systems (i.e., receiving more that, 5,000 gallons per day). In truly critical situations, such calculations can also be performed f or smaller household systems.

Several basic generalizations about septic systems can be made:

1) Septic tank leach field systems typically provide a high degree of treatment for wastewater; 2) Current large lot, low population-density zoning serves to minimize pollution of ground or surface waters; 3) All septic systems will pollute the groundwater directly beneath it and down gradient from it to a certain extent, thus septic systems create a "zone of influence" where groundwater is not drinkable. As effluent travels through soil, various purification processes take place, and the effluent will generally be rapidly retained to a quality suitable for drinking or discharge to a fishable-swimmable stream; 4) Many of us are safely drinking some amount of wastewater that has been treated by these natural processes.

There are a variety of pollutants that are contained in domestic sewage which merit some consideration in this discussion.

Biochemical Oxygen Demand (BOD) and suspended solids are two pollutants in wastewater which are of prime concern in the degradation of surface water bodies. The average BOD in septic tank wastewater is 150 mg/l; the average concentration of total suspended solids is 140 mg/I according to the National Water Well Association. Much of the equipment at a large municipal sewage treatment plant is there to remove these two wastewater components.

The combination of the septic tank, leaching system biocrust, and soil material is so effective in treating these components that within four feet of the system, the BOD and suspended solids will be reduced by 90-98%. Therefore, these pollutants are generally not a concern when considering groundwater impacts from a septic system.

Knowledge of toxic substances and their effect on humans is still very limited, as is specific information about their removal in a soil system. The best information available at this time indicates that roughly 50 hydrocarbon compounds may be contained in a typical domestic sewage sample, and five or six of these may be considered "toxics" under current standards. Numerous instances of groundwater contamination from hazardous organic compounds disposed of via septic tanks, particularly trichloroethylene's, have been recently documented.

Toxic chemicals are treated in the soil by sorption, biodegradation, dilution, and being passed off as vapor, but they may also react chemically to form additional compounds. Heavy use of certain products such as degreasers, photochemicals, or septic additives have been known to create contamination problems.

Domestic sewage also contains large numbers of bacteria. For example, the average concentration of fecal coliform bacteria in septic tank effluent is 1,200,000/100 ml according to the National Water Well Association. Most of these bacteria are not harmful.

However, in certain cases, disease causing bacteria may be produced and survive the rather hostile environment of the septic tank. When the septic tank effluent passes through the biocrust layer of the leaching field, a great many bacteria will be removed by filtering through the crust layer. This biologically active crust layer forms at the interface of the crushed stone in the leaching field and the surrounding soil. The extent of this interface must be very carefully sized for effluent to enter the soil on a long term basis or the system will fail.

Studies have shown that 99% of the bacteria discharged in septic effluent is removed within several feet of the leaching system. The balance of bacteria, and those discharged when a crust section breaks through, have a limited survival time in soil, with 3 to 6 weeks being a reasonable figure. Since the velocity of groundwater and effluent is generally very slow, 25 feet per day or less in most of Connecticut's soils, pathogens generally do not survive long enough to migrate from lots of substantial size.

Many of the same renovation principles for bacteria apply to viral organisms, with one distinct difference. Viral organisms can survive for extended periods of time in the zone of saturation, and therefore may travel greater distances if they reach the groundwater table. The critical safeguard in virus removal is the preservation of an adequate depth of unsaturated soil between the leaching system biocrust and the water table.

Most research in the laboratory and field indicates that two feet of unsaturated, porous soil can adsorb viruses very effectively. This means that the actual flow lines should be at least this long to ensure good viral removal. This number is somewhat more stringent than the current Health Code requirement of 18 above a seasonally high water table, making conservative appraisal of seasonal high groundwater levels important. The current DEP standard is that the system bottom be placed two feet above the modified high groundwater table which will occur with the system in operation.

As discussed in the previous chapter, nitrogen is a nutrient which can adversely impact aquatic habitats. In addition, the nitrate and nitrite forms of nitrogen can play a triggering role in methemoglobinemia. and are suspected of some involvement in other conditions. Standards for raw drinking water in Connecticut are established at maximum concentrations of 10 mg/l for the nitrate and nitrate forms of nitrogen. overly intensive developments utilizing septic tank leach field systems have contaminated wells above this established standard in a number of instances.

In general, such contamination has occurred with high density, defined here as less than one-half acre per lot, single-family developments in sandy soils, with shallow wells for water supply. The average concentration of total nitrogen in septic tank effluent is 50 mg/l according to the National Water Well Association.

Nitrogen is discharged in human waste and emerges from the septic tank as ammonium and organic nitrogen. Some nitrogen is removed in the tank and the leaching system, but the balance will be delivered to the aerobic zone of soil around the leaching system. There will be some nitrogen uptake and utilization by plants, with the remainder being nitrified or, in other words, converted to the highly mobile nitrate form. 

From that point the "treatment" available is dilution by infiltrating rainfall and other recharges to the site, although actual thorough mixing would only take place at a stream outfall or well.

Current DEP practice is to require that the applicant's property have a size and configuration to allow enough infiltrated average daily rainfall to dilute the nitrogen discharge to the drinking water standard at the down-gradient property line. For single-family homes, this calculation normally would require lot sizes at an absolute minimum of 0.6 acres with one acre a suggested minimum. This does not mean that a higher density cannot be achieved with carefully planned residential development.

One final point regarding nitrogen is the relationship of nitrogen discharges to wetlands. According to Section 22a-36 of the Connecticut General Statutes, a stated valuable attribute of wetlands is their ability to purify groundwater. Nitrate nitrogen in septic tank effluent discharging with groundwater to a wetland enters an anaerobic soil condition rich in carbon. This condition is ideal for gentrification, where the nitrogen is released into the atmosphere as a gas, completing the cycle.

Phosphorus is a component of wastewater which serves as a critical nutrient for plant life. If phosphorus is discharged to a lake or other impounded waterbody in the right proportion to nitrogen, the aging process of the water body known as eutrophication can be accelerated. Most phosphorus in septic system effluent assumes a soluble form. Phosphate is generally adsorbed readily by soil through the precipitation of iron, aluminum or calcium phosphates. The average concentration of phosphorus in septic tank effluent is 20 mg/I according to the National Water Well Association.

There are laboratory techniques which provide a conservative estimate of the capacity for specific soils to adsorb phosphate. These values can be utilized to calculate the ability of a given development site to handle the phosphate discharged from a septic system. Soil also has an ability to regenerate its sorption capability with time. For modern lot sizes, the calculated values seldom show that phosphate leaching will pose a problem. Indeed, most analyses indicate total removal within a few feet of a leaching system.

However, this type of analysis does not account for channels in the site which will transmit phosphorus-bearing wastewater past sorption sites. Under certain conditions, such as very sandy soils, high water table, shallow fractured bedrock, or a combination of these factors, phosphate from septic tank effluent may enter and contaminate groundwater or adjacent surface water bodies. This factor is of prime concern when the leaching system is to be installed proximate to an impoundment or a close tributary stream.

In summary, under most conditions with good design and installation, septic tank leach field systems will provide excellent treatment, purifying wastewater to drinking water quality within a short distance. Certainly, improperly designed, installed or operated systems will not be able to purify wastewater.

However, even in areas of intensive development or in areas with highly restrictive conditions, proper engineering analyses of soils. etc. during system design can avoid many of the common septic system problems. The most desirable location for septic disposal systems are in moderately well drained loamy soils. These soils contain a well-oxygenated, unsaturated zone which can be very effective in removing pathogens and phosphorus from wastewater providing flow is not too rapid.

 

7. SEWER PLANTS

Sanitary sewers carry the waste water from residences, commercial buildings, industrial plants and institutions to a wastewater treatment plant. The treatment plant's basic function is to speed up the natural processes by which water can be purified and make the wastewater fit for discharge into streams or for reuse.

Common components of this wastewater include organic wastes and ammonia, disease causing organisms, plant nutrients, synthetic organic chemicals, and mineral substances. Each of these components of sewage is discussed below.

Sewage generally contains both organic wastes and ammonia. Ammonia is derived from the biological degradation of many nitrogen containing compounds, such as urea, the chief component of urine. These oxygen demanding wastes are usually destroyed by bacteria if there is sufficient oxygen present in the water. However, an overload of organic wastewater discharges can result in oxygen depletion and ammonia toxicity in the receiving surface water body. Too little dissolved oxygen, or too much ammonia, can have harmful effects on fish and other aquatic life.

A wide variety of disease-causing organisms which can be carried into surface and groundwaters may also be present in sewage. Modern disinfection techniques, such as chlorination, have reduced the danger of this type of pollutant. This parameter, however, must be constantly monitored.

Sewage treatment plant effluents that have large discharge rates relative to stream flow, such as occurs along the Still River, may adversely impact stream life due to residual chlorine. Where such problems are suspected, DEP conducts monitoring to identify the extent of the problem.

Plant nutrients, such as carbon, nitrogen and phosphorus, are typically present in large amounts in sewage. These nutrients are necessary for aquatic plant life and support and stimulate their growth. Standard biological waste treatment processes do not remove the phosphorus and nitrogen to any great extent. In fact, the treatment breaks down the organic form of these elements, in which form they are part of a large complex molecule, into a smaller and simpler molecule. This simpler molecule is more readily used by plant life. An excess of these nutrients in water bodies may result in the prolific growth of aquatic plants. The end result of this process, known as eutrophication, is the transformation of a water body into a bog or marsh.

High nutrient levels have been implicated as the source of the intense algae blooms in Lakes Lillinonah and Zoar. One of the major sources of the nutrient phosphorus to these waters has historically been the sewage treatment plant discharges of Danbury, Bethel, and New Milford. This nutrient loading is now being controlled however through the seasonal removal of phosphorus from the treatment plant discharges.

Synthetic organic chemicals may also be present in sewage. These are substances consisting largely of carbon and hydrogen combined with oxygen, nitrogen, sulfur, sodium, chloride, bromide, or other inorganic chemicals. They are usually large molecules which do not occur naturally but are mainly manufactured by the chemical industry. Their structure and chemical composition are tailored by the chemists to serve various uses. Examples include detergents, pesticides, and many industrial chemicals.

These synthetic organic substances are resistant to biological breakdown since they are indigestible to the organisms that normally decompose sewage. Many of these substances are toxic to insects, fish, and other aquatic life. Their possible harm to humans is largely unknown and still being studied.

Inorganic chemicals and mineral substances can also be found in sewage. These include numerous compounds of various elements such as calcium, magnesium, sodium and potassium combined with other elements or molecules such as chloride, sulfate and phosphate. These substances may interfere with natural stream purification, but do not represent a threat to aquatic life unless concentrated to extremely high levels. If the compounds are present as insoluble suspended solids, they can be removed by letting them settle in the settling tank of the treatment system.

Treatment of today's wastes in sewage treatment plants is demanding new and more sophisticated processes in order to effectively control the degree of pollution. In addition to the conventional primary and secondary treatment of wastes, new methods of advanced waste treatment are being applied such as specialized biological treatment to remove nitrogen and phosphorus, and chemical separation techniques such as reverse osmosis, distillation, and adsorption through the use of activated carbon.

Finally, it should be noted that the growth potential in a sewer service area is directly related to the design capacity of the sewage treatment plant and the assimilative capacity of the receiving stream. When this capacity is reached, growth potential is limited as DEP will not issue discharge permits to a facility that significantly degrades water quality. Recently, the center area sewer system in Ridgefield reached its limit and a moratorium on all new hookups to the system was implemented by the Town. Until this treatment plant is expanded, estimated to take three years or more, no new hookups to the system will be allowed.

As the discharges to a receiving stream begin to overload its assimilative capacity, more advanced treatment measures become required and associated costs typically increase exponentially. Thus in many sewer service areas, there is a need to balance the benefits of growth with the increasing costs for water quality treatment.

8. RUNOFF

The land area from which water drains to a given point is a drainage basin, also known as a watershed. The drainage basins of smaller streams when added together make up the drainage basin of the larger stream into which the smaller streams flow.

The purity of water in a stream to a great extent correlates with the overall level of development and activity that exists in the drainage basin upstream of it. Another way of saying this is that water quality is a characteristic of the land which contains and yields it for use, and therefore, different land use and population density policies should be applied to drainage basins depending upon the degree of water purity desired.

Activities which contaminate water supplies can be divided into two basic categories, point and non-point. Point sources of pollution are those which are confined to a single, identifiable and discrete point of entry. For instance, waste discharge pipes are point sources of pollutants. Non-point sources are diffuse, indefinite and general sources of pollution and include watershed runoff.

The most intractable class of pollutants is non-point chemical contaminants. In this category fall many substances which inevitably accompany intense land use, such as pesticides, fertilizers, road salts, hydrocarbons and heavy metals. These substances pose the most severe challenge to regulatory systems for two reasons, their relatively unknown physical consequences and their immunity from traditional legal deterrents.

The water quality effects of stormwater runoff have historically received little attention. Recent research has underscored the potential significance of this pollution source, however. According to the "Results of the Nationwide Runoff Program" prepared by the US EPA in 1983:

1) heavy metals (especially copper, lead and zinc) are by far the most prevalent priority pollutant found in urban runoff; 2) some of these metals may represent a significant threat to aquatic life and also pose a hazard to human health if water supply intakes are in close proximity to urban stormwater discharges; 3) the organic priority pollutants, such as various hydrocarbons, were detected less frequently and at lower concentrations than the heavy metals; and 4) coliform bacteria are present at high levels in urban runoff and can have a significant negative impact on the recreational uses of lakes.

Also, 5) nutrients are generally present in urban runoff, but concentrations do not generally appear to be high in comparison with other possible discharges to receiving water bodies; 6) oxygen demanding substances are present in urban runoff in concentrations approximating those in secondary treatment plant discharges; and 7) total suspended solids concentrations in urban runoff are fairly high in comparison with treatment plant discharges.

It should be noted that the effects of urban runoff on receiving water quality are highly site-specific. They depend on the type, size, and hydrology of the water body; the urban runoff quantity and quality characteristics; the designated beneficial use; and the concentration levels of the specific pollutants that affect that use.

Techniques identified in the EPA report to control urban runoff quality include detention devices, street sweeping, grass swales and recharge devices. Detention basins, recharge devices, and grass swales were found to be effective in providing improvements in urban runoff quality. Street sweeping, however, was found to be generally ineffective in improving the quality of urban runoff. Due to the potential impact of runoff on water quality, some local communities have begun to develop and implement stormwater management programs incorporating water quality objectives.

An interesting study of three adjacent watersheds in the town of Fairfield entitled "Detection of Non-Point Pollution of Small Streams in Southwest Connecticut" by S. Bongiorno et al, 1976, demonstrates the relationship of land development to water quality. All three areas have similar geology of crystalline bedrock devoid of any calcium carbonate deposits. The easternmost basin, the watershed of the Rooster River on the Bridgeport-Fairfield line, is highly urbanized with a high density of dwellings in multiple family and much quarter-acre lot zoning.

The watershed of the djacent Mill River is moderately urbanized and that of the Sasco River to the west of the Mill River is semi-rural. Ninety percent of the homes in the Rooster River basin are connected to sanitary sewer systems which carry waste materials to treatment plants. The other two watershed areas dispose of wastes in septic tanks.

The study showed that the water quality of the Rooster River in the most highly urbanized watershed was worse in almost all pollution parameters than that of the other two rivers despite the fact that the Rooster has had sanitary sewering. The river's water quality was downgraded by street and surface runoff which was flushed into storm sewers. Such stormwater runoff can contain many chemicals such as lawn fertilizers, organic herbicides, pesticides, and metallic ions which can reach surface waters through storm sewers and significantly lower the quality of the water. Rooftops, paved areas, automobiles, and lawns in a watershed area each makes its contribution to the receiving waters. Some of the specific conclusions of this study were as follows:

1) Since the future of a stream is determined mainly by what happens in the watershed, the central question at issue is how can suburban areas be developed with the least possible deterioration of the riverine system from the pervasive influence of non-point pollution? Ecological principles teach us that ad hoc treatment of symptoms directed to cleaning water once it has reached a stream is no substitute for comprehensive planning based on the watershed unit. One of the most important goals at the watershed level is to maintain the functional integrity of the inland wetlands.

A paramount finding of recent work has been elucidation of the significant role that wetlands play in pollution filtration. Removal of pollutants such as nitrate occurs in the undisturbed ooze beneath wetland vegetation. A significant key to stream water quality improvement is therefore the conservation of inland wetlands.

2) A second goal at the watershed level is the preservation of stream buffer zones. Forest ecologists have recently discovered that natural strands of vegetation, left along a stream, in otherwise disturbed watersheds where clear-cutting logging operations are involved, can work to trap nutrients on the land. If allowed to move into the streams by unimpeded overland flow, these sue nutrients would become pollutants and lower water quality. It is therefore understandable why townwide land use plans often emphasize the need to preserve strips of natural vegetation along streams to minimize water pollution by purifying water as it moves toward the stream as well as absorbing excess runoff.

3) Watershed level planning essentially calls for managing runoff within watershed boundaries. If engineering and architectural designs foster the "throwing away" of runoff after it has washed across parking lots, streets, and the lawns of suburbia, there is little hope in controlling non-point pollution in local rivers. 

However, the community can work to reverse this trend by encouraging a wide-range plan of water retention by the individual homeowner, the business or commercial proprietor, as well as the town itself. An effort can be made to absorb a stipulated portion of roof, driveway, street or parking lot generated runoff. To this end a number of alternatives have been proposed: underdesigned storm sewers, the use of porous pavements where feasible, and storm retention ponds.

4) Soil scientists have known for a long time that increasing the percent of organic matter in soils, as would be accomplished through use of rough covers that trap leaves, substantially improves the water absorbing and holding capacity of the soil. Yet, modern suburban mores promote the opposite by the planting of extensive lawns, which also contribute inorganic fertilizer to nearby streams in runoff, whose soil tends to become compacted and less absorbent as soil aggregates break down because of loss of organic matter through repeated raking. By carpeting the earth around homes and commercial establishments with smaller lawns and more rough cover, significant reduction in suburban surf ace runoff could be realized.

An interesting series of studies, prepared for the HVCEO in 1980, projected the probable impacts of non-point sources on five subwatersheds of the Still River drainage basin. Generally, these studies concluded that the BOD concentrations would worsen and become more significant, coliform standard violations would be frequent, nitrogen concentration is not and will not be a problem, phosphorus concentrations will increase and significantly exceed the desirable limit of 0.03 ppm, and concentrations of the heavy metals zinc and copper are expected to violate the aquatic life standard. Recommended practices to curb these adverse impacts included erosion control, run-off control, improved urban cleanliness, and better agricultural management.

The impact of development in the watersheds of public water supply reservoirs is a particularly important concern. About one quarter of the Housatonic Valley Region's land area is in existing public water supply watersheds. A fundamental issue is the determination of what extent public water supply watersheds should be protected from pollutant sources versus the heavy reliance upon treatment of the resultant drinking water. 

There are extreme applications of either principle. All public drinking water supply watersheds cannot be restricted from any other use. Conversely, raw water sources cannot be endlessly degraded in expectation of effective remedial treatment before consumption.

Typically, water treatment at a municipal facility involves a number of steps to help ensure potability. The treatment plant fed by West Lake Reservoir in Danbury provides an example. Water is withdrawn from the Reservoir and treated with alum (aluminum sulfate) to help precipitate sediment. The mixing of the alum and water takes plate in large flocculation tanks where much of the sediment settles. The water is then slowly filtered through beds of sand to remove finer grained sediments and bacteria. Following this step, the water is then treated with chlorine to further control bacteria, fluoride to reduce tooth decay, and sodium hydroxide to neutralize pH. After testing for water quality, the water is then ready for distribution.

Additional treatment measures may be desirable or needed at other water treatment plants. Aeration is one such treatment measure. This bubbling of the water facilitates the diffusing into the atmosphere of gases in the water which may cause unpleasant odors and taste. Examples of gases released include volatile organics and hydrogen sulfide, which can cause a rotten egg odor. Aeration can also cause other chemicals, such as inorganics, to settle to the bottom of the treatment tank as particulates. Carbon filtration is another treatment measure which may be necessary in order to control certain contaminants such as synthetic organic chemicals.

Regular monitoring and testing of public water supplies for contamination is required by federal and state drinking water regulations. It should be noted however, that many contaminants do not fall within the parameters of the Safe Drinking Water Act and may not be detected in routine testing. More detailed testing for these other parameters is usually only implemented when a specific threat to a water supply has been discovered, such as a nearby chemical spill.

Development within a public water supply watershed can lead to erosion and sedimentation and the degradation of water quality from a variety of chemical compounds such as road salt, pesticides and herbicides, fertilizers, hydrocarbons, and automotive exhausts. These chemical compounds generally enter the hydrologic regime as watershed run-off. Authorities are not in agreement as to the ability of available treatment practices to combat the wide range of potentially hazardous substances which may affect a public water supply.

Exacerbating this uncertainty is the knowledge that once water resource lands have been converted to another use, their reclamation is rarely, if ever, possible. Therefore, factors such as acceptable margins of safety, duration of adverse impacts and the risks of acting with incomplete information assume critical importance. These intangible components dictate that from the public health perspective, water supply basins should be developed conservatively wherever possible.

9. EUTROPHICATION

All lakes and ponds are subject to eutrophication. This is an aging process which results in a decline in the environmental health of a waterbody, and a reduction in its recreational utility and aesthetic appeal. Eutrophication is a gradual natural process which may be accelerated by man's use of a lake and its associated watershed. Through considerable effort and commitment, the eutrophication process is controllable and manageable. Nearly every lake and pond in Connecticut is in need of "preservation" management to slow down the eutrophication process and prolong its life. Many lakes and ponds are also in need of "restoration" management to correct or reverse eutrophic conditions brought about by the lack of prudent resource management in the past.

Eutrophication is caused by the enrichment of the lake with plant nutrients from its surrounding watershed land. Nutrients are inorganic elements that are necessary for the growth of plants and animals. Phosphorus has been found to be the limiting nutrient in the eutrophication process in most Connecticut lakes. The key to controlling the eutrophication process, therefore, is controlling phosphorus enrichment.

During the eutrophication process, many lake characteristics undergo dramatic changes. To a lake user, major consequences are that algae blooms increase in frequency, intensity, and duration; beds of aquatic plants become dense and more extensive in coverage of the lake bottom; sediment deposits accumulate, shoal areas develop, and the lake becomes shallower; and the oxygen content of bottom waters declines. As these conditions become pronounced, recreation opportunities become seriously impaired. During the latter stages of the eutrophication process, the lake evolves to a wetland such as a swamp, marsh, or bog.

The rate at which eutrophication advances is determined by the rate at which the lake is fertilized by its watershed. Under natural conditions, nutrient inputs from a forested watershed are minimal and it may take centuries for a lake to change in appearance. However, man's development and use of a lakes watershed typically results in greater nutrient generation within the watershed, and an acceleration in the rate of eutrophication. If man's watershed activities are not controlled, severe lake eutrophication can be brought about in a matter of decades.

There are three basic stages of eutrophication which are used to describe the ate of a lake. These stages are termed oligotrophic, mesotrophic and eutrophic. Oligotrophic refers to lakes which are in the early stages of the eutrophication process. mesotrophic refers to middle aged lakes, and eutrophic refers to lakes in the latter stages of the eutrophication process.

The DEP recognizes four trophic classifications for lakes in Connecticut. Here is the trophic status of the major lakes in the Housatonic Valley Region:

1. Loligo-Mesotrophic
   Candlewood
2. Mesotrophic
   Ball Pond
   Squantz Pond
3. Melo-Eutrophic
   Mamanasco
   Taunton Pond
4. Eutrophic
   Kenosia
5. Highly Eutrophic
   Lillinonah
   Zoar

Source: The Trophic Classification of 70 CT Lakes, by DEP, 1982.

An excellent reference on the process of eutrophication and alternative control techniques is "A Watershed Management Guide for Connecticut Lakes", by the Connecticut Department of Environmental Protection.

10. EROSION

Erosion is usually defined as the wearing any of soil material due to the singular or combined effects of water, wind, ice, and gravity. On undisturbed vegetated land, erosion occurs at a relatively slow rate and typically poses few environmental problems as a result. Sedimentation, the deposition of soil at a location away from the site of its erosion, also occurs under natural conditions at a relatively slow rate and is of little consequence in most instances. 

However, land use activities that remove or destroy ground cover result in exposure of soil to the erosive forces of wind, water, ice, and gravity. Under exposed conditions, erosion and sedimentation can occur at accelerated rates many times greater than normal.

The water quality problems associated with sedimentation are numerous. The most obvious of these is deposition of sediment in lakes and rivers which reduces their water storage capacities. Other effects are less obvious. Sediments can physically transport herbicides, pesticides and nutrients.

They may also change the pH of receiving waters, reduce dissolved oxygen by exerting a biochemical oxygen demand, and increase turbidity, thereby killing aquatic organisms, reducing photosynthesis, and destroying wildlife habitats. Management programs can serve to eliminate these deleterious effects. Usually, the control of the pollution source is far more effective than attempting to restore the water once the damage has been done.

The control of erosion from new development usually involves fairly simple management measures such as proper grading, hay bales, silt fences, sediment retention areas, and revegetation of disturbed areas. These measures are described in detail in the "Connecticut Guidelines for Soil Erosion and Sediment Control" published by the Connecticut Council on Soil and Water Conservation, 1985 (updated in 2002). 

Connecticut recently passed Public Act 33-388 requiring that erosion and sediment control plans be prepared for new development proposals. Effective implementation of this law should significantly reduce the threat of erosion and sedimentation from now development activities.

11. WETLANDS

There is substantial wetland acreage within every municipality in the Region. These areas play a significant role in preserving water quality. The discussion of wetlands presented in this section was largely summarized from an article appearing in the DEP Citizens' Bulletin, dated May 1984.

Inland wetlands are defined as those soil types designated as poorly drained, very poorly drained, or flood plain and alluvial by the National Cooperative Soils Survey of the USDA Soil Conservation Service. Watercourses are those areas which may lack the above soils designations but are characterized as "rivers, streams, brooks, waterways, lakes, ponds, marshes, swamps, bogs, and all other bodies of water, natural or artificial. Most wetlands are directly associated with water courses.

By examining a poorly drained soil profile, the effect of a high water table can be seen. In the lower horizons, the subsoil color is washed out and appears light gray. Just above this area, bright red and brown stains may appear against the darker background. This color pattern is called mottling and forms because of the fluctuating water level's effect on chemical and biological processes. The more poorly drained the soils, the closer to the surface this mottling or grayness occurs. The soil may be completely gray if the water table is permanently high.

All soils have some organic matter in them, but organic soils are dominated by the remains of plants and animals throughout their profile. Organic soils, peat and muck are considered wetland soil types. Peat is composed of slightly or non-decayed organic materials, whereas muck is markedly decomposed to the point where no stems or leaves can be seen in the soil.

Activity within wetland and watercourse boundaries needs to be prudently regulated. Wetlands contribute a great deal to maintaining the environmental quality of the surrounding area. They do this through flood storage and control, pollution filtration, biological productivity including wildlife habitats, and providing open space.

Wetlands have an ability which, if not overtaxed, can filter or take up pollutants from runoff before it enters the adjoining watercourse. A wetland thus acts as a buffer zone to trap sediments from naturally eroding areas. However, increased development along the watercourse will hinder a wetland's capability to trap the sediments unless effective measures are implemented to control erosion and sedimentation at the construction site.

A wetland can also biologically break down or regulate the timing of transport of some pollutants that flow through it. In a study on the effect of discharged effluent on a neighboring wet meadow, there was a marked annual decrease in biological oxygen demand, and a delay in the release of nitrogen containing compounds and phosphorous containing compounds. The vegetation, as well as the sediments, helped to retain these nutrients during the growing season, releasing them during a period when they would be less harmful to the environment.

As discussed earlier, nitrate nitrogen in septic tank effluent discharging with groundwater to a wetland enters an anaerobic soil condition rich in carbon. This condition is ideal for dentrification, where the nitrogen released into the atmosphere completes the nitrogen cycle.

The relationship of phosphorous to wetlands was further elaborated upon in a 1983 DEP report entitled "Diagnostic/Feasibility Study for candlewood Lake." According to that report, scientific research has demonstrated that wetlands play a vital role in regulating the timing of transport of phosphorus to downstream waters. During the spring and summer biological growth period, wetlands remove significant amounts of phosphorus from overlying waters and effectively withhold that phosphorus from transport downstream.

Mechanisms by which wetlands retain phosphorus include physical entrapment of particulate phosphorus, chemical sorption by organic matter and soil particles, uptake by aquatic plants and attached algae, and utilization by bacteria and other microorganisms. During the fall and winter, wetlands release phosphorus when decomposition of wetland vegetation takes place. Transport of this phosphorus to downstream waters subsequently occurs at a time of the year when the phosphorus is least likely to contribute to nuisance algae blooms and weed growth.

Thus, although little phosphorus is permanently withheld by wetlands on an annual basis, the spring and summer storage, fall and winter release pattern of phosphorus flux through a wetland serves to minimize summer algae blooms and weed problems in downstream water.

The perpetuation of a wetland's phosphorus regulatory function involves maintaining the wetland in a natural state. Alteration or elimination of the wetland reduces or eliminates the effectiveness of this regulatory role and contributes to a worsening of the trophic conditions in downstream waters.