Low Flow Inventory

Charles River Basin

Observations

Numerous low flow events have been observed across the upper Charles River Watershed. For example, Jar Brook in Holliston was only a few inches deep in August of 1995 and dried completely from late August to early October (3). Cedar Swamp and Weston Pond upstream of Hopping Brook in Holliston were also extremely dry with little to no observable flow through the summer and fall of 1995, a year with below average precipitation (3). Bogastow Brook in Holliston and Millis also ran dry that summer, although Dopping Brook just upstream still had several inches of water (3). In Franklin, Mine Brook flows were too low for DEP staff to sample macroinvertebrates near groundwater withdrawal points (1). Similar low flow conditions precluded sampling on Rock Meadow Brook in Westwood, although staff believed that this may have been a naturally occurring condition because there were no active groundwater wells upstream (1).

Suspected Causes

Water Withdrawals Several groundwater wells in the Town of Holliston are suspected to have effects on streamflow levels. The Zone II delineation report for wells numbers 1 through 6 in Holliston states that Bogastow and Hopping Brooks are recharged by groundwater for most of the year, but during drier periods nearby wells may induce infiltration from these streams (4). The Charles River Nonpoint Source Action Plan suggests that Dopping Brook, a tributary of Bogastow Brook in Holliston, should be monitored for impacts from these same groundwater withdrawals by collecting streamflow and benthic macroinvertebrate data (3).

Dam Management Beaver Brook Reservation on the Belmont / Waltham town line has several water control structures that maintain water levels in Mill Pond and Duck Pond. DEP staff observed that the Beaver Brook streambed was dry from Duck Pond to the lower end of the Reservation during 1995 due to water level management at Duck Pond outlet. This stretch of the Brook has “superb” fish and macroinvertebrate habitat features, but has a moderately impaired benthic macroinvertebrate community because of flow disruptions like the one observed in 1995 (1). The photo above shows the dam at Duck Pond, looking upstream, with no water passing over the spillway on August 15, 2002. A small amount of water can be seen in the photo seeping through the base of the dam, creating the trickle down the streambed.

Bypassed Reaches/Diversions The Milford Water Company diverts water for public water supply from Echo Lake in Hopkinton. The stretch of the Charles River from Echo Lake downstream to Dilla Street in Milford had excellent habitat for fish and benthic macroinvertebrates when surveyed by DEP staff, but there was little to no flow in this section to support aquatic life (1).

Consequences

Pollution Low flows may compound the problem of suspected septic system failures on Bogastow Brook in East Holliston. The problem of concentrated pollutants may not only impact aquatic life here, but also the water quality of the community water supply located between Fiske and Central Streets (1).

On Powissett Brook in Westwood and Dover, extremely low flows during summer of 1997 contributed to excessively low dissolved oxygen concentrations and an impaired benthic macroinvertebrate community with few pollution-tolerant organisms. DEP staff suggested that these low flows may have been naturally occurring since there were no known upstream groundwater withdrawals (1).

Aquatic Flora and Fauna As part of the state’s water quality assessments, DEP staff sampled benthic macroinvertebrates at many locations within the watershed. Several of these locations had benthic macroinvertebrate communities that were limited or degraded by low streamflows. For example, along the Charles River from Dilla Street in Milford to the Milford wastewater treatment plant in Holliston, DEP staff observed little to no flow. Aquatic habitat here was limited by the lack of water, and DEP staff found that the resident aquatic community showed signs of degradation. On the Mill River in Norfolk, DEP staff discovered that rheophilic, or flow-loving, macroinvertebrates that were found at the upstream reference site were replaced with slow-water forms in this section of the river. On the Waban Brook in Wellesley, streamflow was below the 7Q10 level on the sampling date in 1997, and water levels were so low that quantitative macroinvertebrate sampling could not be conducted. Qualitative sampling revealed a lack of mayfly and stonefly larvae, two groups of macroinvertebrates that were expected in this reach and are generally intolerant of pollution. Staff suggested that the high water temperature (21.3º C or 70º F), partly a result of low streamflows, may have eliminated them from this stream reach (1).

Current Events

The Charles River Watershed Association is measuring stream flow in nine tributaries to the Charles River in support of the state's development of Total Maximum Daily Loads (TMDL) for pollutants. The tributaries include: Bogastow Brook, Chicken Brook, Fuller Brook, Hopping Brook, Mill River, Mine Brook, Stop River, Trout Brook, and Waban Brook (5).

References & Resources

1. Fiorentino, John G., Kennedy, Laurie E. and Mollie J. Weinstein. Charles River Watershed 1997/1998 Water Quality Assessment Report, Report Number 72-AC-3, DWM Control Number 16.0. MA DEP Bureau of Resource Protection, Division of Watershed Management.
2. IEP, Inc., Consulting Environmental Scientists. May 20, 1986 . Town of Holliston Brook St. and Central St. Wells. DEQE Chapter 233 Aquifer Land Acquisition Application.
3. Barber, Rosalia, Duval, Brian, and Jeffrey Brownell. Nonpoint Source Action Plan, Charles River Basin . July 5, 2001 . MA DEP.
4. Whitman and Howard, Inc. March 1996. Numerical Groundwater Flow Modeling and Zone II Delineations for Wells No. 1, 2, 3, 4, 5 and 6, Holliston , Massachusetts .
5. "Tracking Tributaries". Streamer, A Publication of the Charles River Watershed Association, vol. 33, No. 2. Summer 2002.
6. USGS real-time stream gage data for Miscoe Brook near Franklin.
7. USGS real-time stream gage data for the Charles River at Medway.
8. USGS real-time stream gage data for the Charles River at Dover.
9. USGS real-time stream gage data for Mother Brook at Dedham.
10. USGS real-time stream gage data for Hobbs Brook below Cambridge Reservoir near Kendall Green.
11. USGS real-time stream gage data for unnamed tributary 1 to Stony Brook near Waltham.
12. USGS real-time stream gage data for Stony Brook at Rt. 20, Waltham.
13. USGS real-time stream gage data for Stony Brook Reservoir at dam in Waltham.
14. USGS real-time stream gage data for the Charles River at Wellesley.
15. USGS real-time stream gage data for the Charles River at Waltham.
16. USGS real-time stream gage data for the Muddy River at Brookline.