Low Flow Inventory

North Coastal Basin

Observations

Members of the Saugus River Watershed Association and others are concerned about low flow problems in the Saugus River from its headwaters to the tidal area near the Saugus Iron Works in Saugus. The section of river downstream of the Lynn Water and Sewer Commission dam is particularly affected although the operation of the dam is perceived as only part of the problem (2). For example, the Saugus River from Lake Quannapowitt in Wakefield to the Lynn Water and Sewer Commission’s diversion canal in Lynnfield suffers from low flow problems. DEP staff measured extremely low discharge at the outlet of Lake Quannapowitt in June and July of 1997 (0.05 and 0.02 cfs, respectively).

Likewise, DEM staff measured low discharge in the Lynn Water and Sewer Commission’s Diversion canal in July, September, and October of 1997 (0.17, 0.13, and 0.07 cfs, respectively). These low flows in the Saugus River were accompanied by low dissolved oxygen concentrations of 2.3 and 2.9 mg/l, or 25% and 33% saturation (1). These values are below the criteria for Class B waters.

The upper reaches of the Saugus River were particularly hard hit by the 2002 drought. The Saugus River Watershed Council measured the lowest dissolved oxygen concentrations in the history of their monitoring program, which began in 1991. Less than 1 mg/L of dissolved oxygen was measured at some locations, well below the Class B standard of 5 mg/L! Low flows also caused the river to recede until it was a series of isolated pools in the upper reaches. Without flowing water, the dissolved oxygen levels in these pools plummeted and resulted in fishkills, which included sunfish, largemouth bass, and yellow perch (9).

Low flow problems have also been documented in several other streams in the North Coastal Watershed:
Beaverdam Brook in Lynnfield suffered from low flows (less than 0.1 cfs) and low dissolved oxygen concentrations between June and September of 1997 (1).
At Goldthwaite Brook in Peabody in 1997, DEP staff observed a dry stream bed and guessed that a blockage under the bridge could be one cause, although the impacts of several water withdrawals in the area should also be evaluated (1).

USGS and DEP measured stream flow in Proctor Brook in Peabody during 1997 and 1998 and found very low flows between July and November of 1997 (1).

Suspected Causes

Water Withdrawals The Office of Water Resources listed Hop Brook near Salem as a “high stress” river based on its low discharge per square mile of watershed compared to other rivers in the state (7).

Alewife Brook in Essex has several nearby water withdrawals that may have caused periodic low flow events including the Town of Manchester’s Round Pond Wells #1 and #2, Gravelly Pond surface water withdrawal in Hamilton, the Town of Essex’s Centennial Grove Wells #1 and #2, and Harry Homan Well #1 in Essex.

Centennial Grove Wells #1 and #2 and the Harry Homan Well #1 have a combined yield of 200,000 gallons per day, but during peak withdrawals periods this amount can triple. This means that during the summer when stream flow is naturally lowest up to three times as much water can be withdrawn from these wells to meet summer water demands such as lawn watering and car washing.

Several sources have noted the probable connection between these groundwater withdrawals and stream depletion. During the pump test for the Centennial Grove well the temperature of water being pumped increased about two degrees and this increase was attributed to the influence of warmer surface water being drawn into the well (4). The Conceptual Zone II Delineation report for the Centennial grove and Harry Homan’s wells also supported the theory that streamflow in Alewife Brook may be affected by these wells. Relatively high aquifer transmissivity values and a quick stabilization and recovery during the pump tests indicated that there was a significant amount of induced infiltration from Alewife Brook and the surrounding wetlands. The direction of groundwater flow from nearby hills toward Alewife Brook and Chebacco Lake also indicates that these wells located near Alewife Brook probably intercept groundwater flow to the brook (6).

Dam Management DEP staff observed stagnant water and no flow to the unnammed tributary below the outlet of Babson Reservoir in Gloucester (1,2). This section is downstream of the public water supply intake at Babson Reservoir as well as Alewife Brook, where low flows were also observed (see Consequences: Aquatic Flora and Fauna). Below is a photo of the nearly dry streambed in Alewife Brook at Pond Street in Essex (left) and the flashboard under Apple St. in Essex with no water flowing over it (right, looking upstream) taken on August 15, 2002.

Bypassed Reaches / Diversions A study of low flows and habitat availability for fish and macroinvertebrates on the Saugus River, funded by the Massachusetts Watershed Initiative Program, found that current streamflow patterns are most reduced compared to historic patterns in the summer and during certain periods of the fall and spring when water suppliers refill their storage reservoirs. The historic alewife run is no longer thriving, but recommendations for minimum flow releases from the Lynn Water and Sewer Commission’s diversion were made to provide stream flow, habitat and forage to increase the population. The following minimum flow recommendations were based on a combination of fish and macroinvertebrate habitat needs and water supply needs: 3 cfs from June 1 to September 30, 6 cfs from October 1 to February 28, 12 cfs from March 1 to April 30, and 10 cfs from May 1 to May 31.

Consequences

Aquatic Flora and Fauna In July 1997 DEP staff observed low flow and low dissolved oxygen concentrations (1.9 mg/L, 20% saturation) in Alewife Brook in Gloucester and Rockport (not to be confused with Alewife Brook in Essex). This stream is classified as Class A, or public water supply source, which means that dissolved oxygen levels should be at least 6.0 mg/L or 75% saturation to support aquatic life and public water supply uses. This section of Alewife Brook had also been chosen as a reference site for benthic macroinvertebrate biomonitoring because of its excellent habitat characteristics including riffles, rocky substrates, and an intact riparian zone. However, one month after identifying this as a reference site, staff were unable to sample this section of Alewife Brook because there was no flowing water (1).

Another low dissolved oxygen concentration (4.8 mg/l, 42% saturation) was measured on Cat Brook near School Street in Manchester and attributed to low flow conditions (0.05 cfs in October of 1997). Interestingly, although the streamflow and dissolved oxygen concentration was poor at this site, the benthic macroinvertebrate community was diverse and included members of nine families of organisms (1).

References & Resources

1. DeCesare, Gregory J., Kennedy, Laurie E. and Mollie J. Weinstein. May 2000. North Coastal Watershed 1997/1998 Water Quality Assessment Report, Report Number 93-AC-1, DWM Control Number 17.0. MA DEP, Bureau of Resource Protection, Division of Watershed Management.
2. Joan LebLanc, Saugus River Watershed Council. Personal communication, March 2002.
3. Gomez and Sullivan Engineers and MA DEM. June 2002. Impacts on Streamflows in the Saugus River from Human Manipulation, Final Report.
4. Cohen, Russ . August 16, 1994 . Memo to John Phillips, Commissioner.
5. Barber, Rosalia. May 4, 2001 . Nonpoint Source Action Strategy, North Coastal River Basin. MA DEP.
6. Earth Tech, Inc. June 2001. Final Report, Source Water Assessment Program Conceptual Zone II Delineation Harry Homan’s Gravel-Packed Wells #1 and #2 and Centennial Grove Gravel Packed Well, Essex Water Department. Essex , MA . Prepared for Massachusetts Department of Environmental Protection.
7. Stressed Basins in Massachusetts . Final draft, OWR version 3. 12/01.
8. USGS real-time stream gage data for the Saugus River at Saugus Iron Works, Saugus.
9. “Dry Season Causes Problems for Saugus River Watershed”. Currents. A Publication of the Saugus River Watershed Council. Volume 10, Number 4, Fall 2002.