Environmental Impacts and Fiscal Considerations of Low Flow

Environmental Impacts
Many rivers and streams across Massachusetts are being seriously degraded by low summer flows due to water withdrawals, interbasin transfers, and watershed development. In fact, the Massachusetts Water Resources Commission recently identified all or portions of many major Massachusetts rivers as “stressed” by low summer flows.

These Rivers include:

Eastern Massachusetts Aberjona River Assabet River Charles River Concord River Ipswich River Neponset River North River Parker River Shawsheen River Sudbury River Taunton River

Central Massachusetts French River Millers River Nashua River Quaboag River Quinebaug River Ware River

Western Massachusetts Farmington River Mill River Westfield River

More frequent and severe periods of low or no flow in summer have a number of effects on our rivers and streams and the animals and plants that live in or near them. These include:

• increasing water temperatures
• higher concentrations of pollutants
• reduced concentrations of dissolved oxygen
• increased vulnerability to predation

Over time, the effects of chronic low flows on river ecosystems can be dramatic. In the Ipswich River watershed chronic low flows have been found to be associated with a dramatic change in the community of fish species inhabiting the river. Fish species characteristic of rivers similar to the Ipswich, but not effected by large summer water withdrawals, have all but disappeared, replaced by species common to lakes and ponds. For more information read case studies of chronic low flows in the Ipswich River and the Assabet River.

In addition to fish, other river dwellers are also at risk from chronic low summer flows. Eighteen of the twenty-one species of freshwater mussels found in New England are declining or threatened according to the United States Fish and Wildlife Service. In addition, fourteen of the thirty-four species of dragonfly associated with flowing waters in New England are rare or threatened.

Entire natural communities can even be threatened by high summer water use. In southeastern Massachusetts and on Cape Cod, globally rare coastal plain pond communities are at risk from excessive pumping of groundwater. Along rivers and streams, rare floodplain forests may be at risk.

Fiscal Considerations
Excessive water use not only harms our rivers, it can be very expensive. Using more water than you need means your community needs more and bigger water supplies, water mains and pumps, and water treatment plants. If you live in a community with sewers, excessive indoor water use means higher sewer charges to pay for larger sewers and pumping stations and larger treatment plants.

Summer water use particularly drives up the cost of water supplies because water systems must be built to meet peak demands. Typically, this means that water systems must be designed and built to meet the highest demand level experienced on the hottest and driest summer day, plus provide for simultaneous emergencies, such as a major fire, or the failure of a large pump station or well. Since summer water use can be two, three, or more times the average water use, this means that most water systems must have capacities that far exceed what is necessary to supply the amount of water used on an average day. All this extra capacity costs money, and if peak summer demands can be reduced, the cost of providing this capacity can be avoided.

The same goes for sewer costs. If the volume of sewage created can be reduced through water conservation, such as the use of high-efficiency toilets, showerheads, and appliances, the capacity of wastewater treatment facilities can also be reduced. During the 1990s, New York City implemented a major water conservation program to reduce sewer flows and avoid the need for additional wastewater treatment plant capacity and to address water supply shortages.

The 1996 Clean Water Needs Survey, compiled by the U.S. Environmental Protection Agency found that between 1996 and 2016, Massachusetts water supply needs totaled more than $6.2 billion in 1996 dollars. Massachusetts water pollution control needs for the same period totaled $3.75 billion. Of these costs, 68% of the water supply needs and 86% of the water pollution control needs are flow related. For these flow related needs, costs can be reduced by reducing the amount of water used and the amount of wastewater created. Conserving water saves rivers, and it also saves money.