Sympaug Brook Watershed in Bethel and Danbury, CT

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INTRODUCTION

Sympaug Brook starts in Bethel near the Redding Town Line. It then runs from south to north thru western Bethel, crossing into Danbury near Route 53 to empty into the Still River. The Danbury Branch rail line and Route 53 generally parallel the watercourse throughout Bethel.

The associated watershed area for Sympaug Brook reaches easterly to the ridge of Shelter Rock north of Downtown and to the Hoyts Hill Area east of Downtown, then also includes the easterly and uphill side of Chestnut Ridge Road.

Then on the west bank of Sympaug Brook, the watershed extends beyond Bethel into the City of Danbury, reaching westerly up to the height of land along Danbury’s Brushy Hill Road.

The Bethel Water Department maintains two water supply sources in the Sympaug Brook Watershed. The first, Eureka Lake and Mountain Pond along with Murphy Brook, is to the west and primarily located within the City of Danbury.

The second is the Chestnut Ridge Reservoir, located in the southernmost part of Bethel along Chestnut Ridge Road not far from the Redding Town Line.

EUREKA LAKE AND MOUNTAIN POND

The Bethel Water Department’s 2006 Water Supply Plan Update provides some useful information about the Eureka Lake - Mountain Pond supply system. These are quite small resources by the standards of the water supply industry, with a combined watershed catchment area of only .75 square miles. The outflow from Mountain Pond is northerly under Long Ridge Road into Eureka Lake.

Eureka Lake was created in 1878 and then Mountain Pond above it in 1901. The Town owns 44% of the combined watershed. Fortunately, the remainder of this watershed catchment area is protected by the Danbury Water Supply Watershed Protection Zone, even though Danbury does not consume their water.

A watershed protection zone has been in force in Danbury since the early nineties. All surface water supply areas in the City of Danbury are protected equally, whether used in Danbury proper or not. The regulatory reference is the Danbury Zoning Regulations, “Section 7, Overlay Zones, 7C. Public Water Supply Protection Zones.”

Bethel's Eureka Lake Reservoir.
Photo courtesy of Rick Gottschalk.

Just to the east of these two little reservoirs, at the bottom of the hill and on the Bethel side of the municipal boundary is Murphy Brook. This short brook flows northerly with the Francis J. Clarke Industrial Park and then Bethpage Drive to its east. This water resource was designed to be an occasional supplemental source for Mountain Pond.

According to the 2006 Bethel Water Supply Plan Update “A diversion in Murphy Brook was installed to supply water to Mountain Pond and Eureka Lake by use of pumping.. The watershed above the diversion is .59 square miles, which is insufficient to sustain a consistent flow adequate to make use of a diversion practical. Murphy Brook only flows during heavy rains or during a prolonged wet season. The diversion has not been used in over 25 years.”

We can infer from this that the diversion is not available when it would be needed most; in the dry season. Still, the Murphy Brook supplement is regulated by CT DEP as a GAA water supply area, as a precaution for public health etc., in a manner identical to state regulation for Bethel’s other surface water resources.

CHESTNUT RIDGE RESERVOIR

The Chestnut Ridge Reservoir was built in 1909. The Reservoir is located in the southernmost part of Bethel along Chestnut Ridge Road not far from the Redding Town Line. A very small part of the Reservoir's watershed reaches south outside of Bethel into Redding.

Bethel's Chestnut Ridge Reservoir.
Photo courtesy of Rick Gottschalk.

The Town owns 55% of the Chestnut Ridge Reservoir Watershed, with the total watershed being .37 square miles. Its safe yield is .17 million gallons per day, as opposed to .13 for Mountain Pond and .20 for Eureka Lake. See the next section for more discussion of this resource.

RELATIONSHIPS BETWEEN RESOURCES

The safe yield for the surface water sources combined is .50 million gallons per day. According to the 2006 Bethel Water Supply Plan “The Eureka Lake supply has taste and odor problems that the existing treatment plant cannot mitigate. The Chestnut Ridge supply is reliant on an aged treatment plant in poor condition.

Of the two plants, the Chestnut Ridge plant presents the more difficult situation. As the lone source of supply for the High Service Area it must be kept in operation continuously, however there is no available space to build a new plant without removing the existing one. Therefore, whether the Bethel Water Department decided to replace the plant or abandon the source, additional supply development is essential.”

Continuing, “The Bethel Water Department has been actively pursuing the development of additional wells behind the Police Station in the East Swamp Aquifer. Water quality and groundwater withdrawal potential has been evaluated and the area deemed a suitable supply development site. Diversion permit applications are currently underway.

Once the additional supply source is developed, an evaluation will need to be made to determine the long term costs of pumping from the East Swamp Aquifer to the High Service Area versus the replacement cost of the Chestnut Ridge Treatment Plant.”

Recent research has found that one potential water supply watershed to hypothetically supplement Chestnut Ridge Reservoir is the nearby Wolf Pit Brook.