Low Flow Inventory

Housatonic River Basin

Observations

Reports of low flow problems in the Housatonic River Watershed include both short and long term disruptions of streamflow. Members of the local watershed team have observed streams suddenly run dry below water supply reservoirs when flow is completely shut off to refill the reservoir (2). In the long term, several diversions deliver water from Cady and Windsor Brooks into the Cleveland Reservoir and leave downstream reaches completely dry. For example, DEP staff observed that the entire flow (22 cfs) of Windsor Brook was diverted to the Cleveland Reservoir, leaving a quarter mile of dry streambed downstream (1). As early as 1939, fisheries biologists noted that the Windsor River could not support coldwater fisheries because flow was reduced to nearly isolated pools during summer (7).

Suspected Causes

Water Withdrawals The City of Pittsfield used the Cleveland Reservoir for 74% of its public water supply in 1998 by diverting an unquantified amount of water from both Windsor and Cady Brooks. Although a large amount of water is diverted into the Cleveland Reservoir, stream flow in Cleveland Brook itself is more typical of a small first order stream. During DEP’s sampling for the 1997/1998 Water Quality Assessment Report, 22 cfs was diverted from Windsor Brook to Cleveland Brook Reservoir, but flows out of the reservoir to Cleveland Brook were only 1.3 cfs (1).

Water withdrawals from Karner Brook in South Egremont exceed the 7Q10 by a factor of 10, although no further information about the impact of these withdrawals is available (8).

Dam Management Local reports of water control structures throughout the basin holding back all flow were further supported by DEP staff, who observed that one quarter mile of Long Pond Brook was completely dry just below the outlet of Long Pond in Great Barrington during summer of 1992 because no water was released over the control structure (1).

Citizens have also reported flow problems in the Housatonic River below the Glendale Hydropower Project in Glendale, which in some cases meant that no flow passed over the dam for up to 8 hours while the impounded area was refilling (3). These reports prompted a FERC compliance review, which found that both operator actions and equipment deficiencies were to blame for the project’s failure to meet the minimum stream flow requirements of its permit. Equipment problems have been resolved and the company now ceases power generation at low flows so that at least a small amount of water passes downstream. DEP's 1997/98 Water Quality Assessment Report recommended that a minimum flow requirement for the bypassed reach be established and incorporated into future permits (1).

Bypassed Reaches / Diversions Both Cady and Windsor Brooks are diverted through an aqueduct to Cleveland Reservoir. One half mile of Cady Brook and one quarter mile of Windsor Brook upstream of Windsor Reservoir are dewatered or completely dry below this diversion (1).

Consequences

Aquatic Flora and Fauna The headwaters of Furnace Brook in Richmond to the inlet of Mud Ponds in West Stockbridge had a slightly impaired benthic community relative to the reference site in the 1997/1998 Water Quality Assessment Report. DEP staff suggested that this was due to naturally occurring low flow conditions, but they also recommended an examination of upstream dams and other control structures to evaluate their effects on streamflow (1).

DEM's Office of Water Resources calculated the Aquatic Base Flow (ABF), or mean August streamflow, for many streams and rivers throughout the Housatonic basin. These flow values are intended to assure healthy aquatic ecosystems, based on the principle that the aquatic community has adapted to survive average August low flow conditions. The ABF values ranged from 0.23 cfsm to 0.64 cfsm across the basin. The following streams were identified as "trout streams", with an Aquatic Baseflow value of 0.27 cfsm (9):

• Umpachene R., Karner Br., Green R., Seekonk Br., Cone Br., Furnace Br., Marsh Br., Beartown Br., West Br., Hop Br., Greenwater Br., Washington Mt. Br., Felton Br., Sawmill Br., Sackett Br., Wahconah Fall Br., Cleveland Br., Bennet Br., Cady Br., Lulu Br., Daniels Br., Secum Br., Town Br., Smith Br., Jacoby Br., May Br.

Current Events
On November 3, 2000, the Old Berkshire Mill Dam on the East Branch of the Housatonic River was removed, the culmination of efforts by the Riverways Programs River Restore staff, corporate partner Crane and Company and many others. Removal of this dam doubled the amount of habitat available to this coldwater fishery, which includes some of the finest trout seen in the area (4).

References & Resources

1. Kennedy, Laurie E. and Mollie J. Weinstein. June 2000. Housatonic River Basin 1997/1998 Water Quality Assessment Report, Report Number 21-AC-3, DWM Control Number 19.0. MA DEP, Bureau of Resource Protection, Division of Watershed Management.
2. Hudson (Hoosic) River Watershed Team, watershed initiative grant proposal.
3. Shep Evans, MACC board member and Stream Team member, personal communication February 2002.
4. Riverways Programs River Restore webpage.
5. USGS real-time stream gage data for the East Branch Housatonic River at Coltsville.
6. USGS real-time stream gage data for the Housatonic River near Great Barrington.
7. Clement, R. and W. Kulish. July 17, 1939 . MA DFW historic files.
8. Miller, Tracey. July 6, 2001. Nonpoint Source Action Strategy, Housatonic River Basin. MA DEP.
9. DEM OWR. May 1999. Water Resources of the Housatonic River Basin: Water Use and Hydrology.