The rivers need a certain amount of water, or flow, in order to support aquatic life, wildlife habitat and recreational opportunities. Precipitation, both rain and snow, help feed the streamflow during much of the year. However, at dry times of the year, especially in the summer and early fall, river flow is supplied by groundwater stored in aquifers.

In the metrowest area of Boston, there are strong development pressures and significant growth. This growth has at least two effects on the aquifers and consequently the rivers. First, more of the land is covered with pavement and buildings which prevents rainwater from percolating into the groundwater and recharging the aquifers. Second, the increased growth places increased demand on water supplies—much of which is pumped from groundwater wells. Ultimately, the aquifers become depleted and are unable to provide adequate flow to the rivers.

In recent years, low river flow has been evident in the headwaters of the Sudbury River and tributaries of the Assabet River. Anecdotal information infers that the low flows are caused by less water in the aquifer, although this will not be verified until scientific studies are completed.

OARS maintains staff gages to measure streamflows at nine tributary stream sites in the watershed; streamflow is recorded for these sites every time water quality is sampled. Streamflow data are also recorded by the USGS at their five continuous flow gages in the watershed (Assabet River in Maynard, Concord River in Lowell, Sudbury River in Saxonville/Framingham, and Nashoba Brook in Acton). Learn more about flow.

On the Sudbury River, the United States Geological Survey has studied and modeled the water flow in the headwaters in order to develop a model to simulate water behavior. This will enable evaluation of alternative water management scenarios. Read the report.

The River Stewardship Council(RSC) provides funding support to local organizations working on these flow issues. In addition, the RSC promotes the use of low impact development techniques in any new projects that may affect the river. Low Impact Development (LID) is an approach to environmentally friendly land use planning. It includes a suite of landscaping and design techniques that attempt to maintain the natural, pre-developed ability of a site to manage rainfall. LID techniques capture water on site, filter it through vegetation, and let it soak into the ground where it can recharge the local watertable rather than being lost as surface runoff.

Most residents of the Sudbury, Assabet and Concord watershed are connected to public water supplies. It is the cumulative effect of each homeowner's water use that results in the growing demand for water, and increased pumping of groundwater from water supply wells. Did you know that landscaping is by far the largest water consumer in the home, and in many cases lawn watering uses public water supplies? Most of this water does not return to the groundwater, as many may think, but is consumed by the grasses and/or evaporates to the atmosphere.

Massachusetts Water Conservation Standards of 2006 are, among other things, intended to reduce the amount of water used by residents and limit non-essential uses, such as lawn watering, in the summer. The guidelines for residential water use are no more than an average of 65 gallons per person per day.  Some wild and scenic shoreline communities still exceed that amount. Summer water use should not exceed a 20% increase over winter use since water sources are more stressed during the summer months and demand is highest, particularly due to outdoor watering.

The RSC has initiated an education campaign to alert the public to the connection between water use, the impacts on our rivers and what individuals can do to make a difference. The effort highlights “water-wise” lawn care methods, as well as other changes individuals can make in their homes to reduce water use. Many communities are proactively addressing this issue as well.

These issues are not unique to the Sudbury, Assabet and Concord Rivers; they are becoming more significant on many of the rivers in Massachusetts, especially those in the eastern part of the State. A number of organizations are creating and compiling resources to help address these issues.

• Massachusetts Audubon Society has created a river toolkit.
• The Massachusetts Riverways Program developed the River Instream Flow Stewards (RIFLS)  to help local groups identify, document and restore rivers and streams suffering from abnormally low flows. Through this process, citizens and local officials will learn about the importance of healthy streamflow, work together to restore more natural flow regimes, and establish high quality streamflow data records for local, regional and state uses.
• Massachusetts Executive Office of Energy and Environmental Affairs has developed a Smart Growth Tool Kit.  Smart growth techniques support well-planned development that protects open space and farmland, revitalizes communities, keeps housing affordable and provides more transportation choices

What can you do to help?

• Calculate how much water  you use in your home. How close are you to the recommended 65 gallons per person per day maximum?
• Calculate the difference between your summer and winter water use. This will help to estimate how much water you use on your lawn and garden. Lawn watering is the largest use of water. Learn many ways to minimize water use on your lawn.
• Minimize the amount of lawn in your yard. Use native plants and other irrigation-free landscaping.
• Install water saving devices in and around your home, including low-flow showerheads, low-flow toilets, rain barrels and cisterns. Find out what rebates or other support your town may offer. Learn more at the EPA’s Water Sense Program.