Wednesday
24Sep2008
Stream Flow
September 24, 2008
Aquatic systems need adequate water quality and water flow to support a healthy ecosystem. In Rhode Island, the management of water supply and protection of stream flows is shared by several agencies (link this to the separate page on water supply management) – the RI Water Resources Board is responsible for developing a fair and equitable allocation of water among users and uses; the RI Department of Environmental Management authorizes withdrawals under the authority of the Clean Water Act and the Freshwater Wetlands Act; the RI Department of Health ensures the safety of public drinking water and swimming/bathing waters while the RI Public Utilities Commission oversees water rates.
Streamflow is dynamic and aquatic organisms need not only water in the stream, but the natural changes in stream flow, to thrive. The WAPAC Streamflow Subcommittee Final Report included the following description of how flows impact stream ecology:
In Rhode Island, the Pawcatuck system (302 sq mi), the sole source aquifer for 14 towns in southern RI and 4 towns in southeastern CT, is particularly sensitive, with low flows especially apparent in the Chipuxet. The Chipuxet Aquifer provides drinking water for the University of Rhode Island (URI) estimated at 12,000 people as well as the Kingston Water District (KWD), with a few more than1,000 accounts. The peak demands on the Chipuxet aquifer fluctuate with the primary users: its largest user URI peaks in fall and spring, while another peak occurs in the summer due to increased water withdrawal by the Kingston Water District. KWD supplies the residential, commercial, industrial, and agricultural water to local users. Private residential wells use groundwater, and turf farms also pump water from the Chipuxet aquifer during the growing season from April through late October. Sewage from water supplied by URI and KWD flows into the Atlantic Ocean, constituting an out-of-basin transfer of water from the Chipuxet Aquifer amounting to 1.317 mgd, (Hershberger et al, 2004). According to the USGS (Wild and Nimiroski 2004) the combined water withdrawals can exceed the river’s capacity.
Flow impacts are also observed in the Hunt River system (Click here to view case study). The Hunt and Annaquatucket Rivers are small coastal streams draining less than 30 square miles each and flowing into Narragansett Bay along the westerly side of Narragansett Bay. The underlying groundwater in the Hunt-Annaquatucket-Pettaquamscutt (HAP) system is found in glacial stratified deposits and is in close hydraulic connection with the surface water system. Three public water suppliers withdraw water from the HAP – the Town of North Kingstown (10 wells), RI Economic Development Corporation for the Quonset Industrial Park (3 wells), and the Kent County Water Authority (1 well). Groundwater is also withdrawn at a privately owned industrial well and at three State-owned wells that provide water to the Lafayette State Fish Hatchery. Extreme low flows have occurred in the lower Hunt during 2005 and 2007 and shifts in fish populations have been documented by RIDEM studies.
In Massachusetts, the Department of Fish and Game’s Riverways Program has developed the pilot River Instream Flow Stewards (RIFLS) to help local groups identify, document and restore rivers and streams suffering from abnormally low flows. Their web site provides information on the flow status of watersheds throughout the state.
According to the RIFLS site the Blackstone River watershed’s capacity for storing freshwater is limited due to small stratified drift deposits for collecting groundwater and limited freshwater wetland areas for storing surface water. For many years, the rivers and streams of the watershed have been dammed to create impoundments to store water for water supply, mill operations and boat passage, particularly during the summer months. The mainstem of the Blackstone receives wastewater from the City of Worcester, much of which originates in the Chicopee and Nashua River basins. Despite this flow augmentation, many sections of the rivers and streams throughout the watershed suffer from unusually low streamflows due to human activity.
Flow in the Blackstone’s Quinsigamond River Basin has been affected by ongoing development and water withdrawals (Blackstone River Coalition, 2008). August monthly flows have declined 55% since 1979. The Quinsigamond River has run dry during parts of the summer in four of the past 10 years.
Low flows have been observed in thirteen streams in the Taunton River watershed. The Canoe River below the Newlands Street Bridge in Norton has severe low flow problems near Well # 3. Stump Brook in Halifax also has recurring low flow problems due to the diversion of water from Monponsett Pond, the brook’s source. Water is diverted to Silver Lake in Kingston to supply the City of Brockton with drinking water. During anadromous fish surveys conducted in the summer of 2002, staff from the Division of Marine Fisheries observed no flow in the Muddy Cove Brook at Hart St. in Dighton, Fall Brook at Glebe St. in Taunton, Sally Richmond Brook at Main St. in Dighton and an unnamed tributary of the Taunton River at Hill St. in Raynham. These streams provide no habitat value for anadromous fish populations when dewatered.
Low flows have also been observed in the Palmer River from the confluence of the East and West Branches of the Palmer River to Route 6 in Rehoboth due to the interbasin transfer of water out of Shad Factory Pond. This water is transferred into the Kickemuit Reservoir in Warren, RI where it is used and distributed by the Bristol County Water Authority.
Streamflow is dynamic and aquatic organisms need not only water in the stream, but the natural changes in stream flow, to thrive. The WAPAC Streamflow Subcommittee Final Report included the following description of how flows impact stream ecology:
“Hydrologists and ecologists have identified five critical components of the flow regime that regulate ecological processes in river ecosystems: the magnitude, frequency, duration, timing and rate of change of hydrologic conditions. These components influence ecological integrity both directly and indirectly, through their effects on other primary regulators of integrity. Modification of flow thus has cascading effects on the ecological integrity of rivers.
Ecologically protective flows are considered to be flows that support desirable biota at densities similar to those expected under natural flow conditions. Streams have a natural flow regime that varies with the seasons and with yearly weather patterns. In the absence of site specific data that allow a better understanding of relations between flow and biotic integrity, flows are sought that generally mimic the essential components of the natural flow regime under the assumption that ecological processes will then foster a desirable aquatic community.
Altered stream flows may adversely affect stream ecology. For example, there may be increased water temperatures, decreased dissolved oxygen levels and increased fine sediment deposition, which can result in a shift from cold water to warm water fish species, decreased productivity and increased fish kills, and stream bottoms rendered unsuitable for fish spawning. Low flows can also affect the ability of rivers and streams to assimilate wastewater.”
Stream Flow Status and Trends
The Narragansett Bay watershed has abundant freshwater, but increasing and competing demands for water resources in Rhode Island and Massachusetts not only leads to uncertain conditions for economic development, but has also begun to dangerously draw down some rivers, ponds and wetlands.In Rhode Island, the Pawcatuck system (302 sq mi), the sole source aquifer for 14 towns in southern RI and 4 towns in southeastern CT, is particularly sensitive, with low flows especially apparent in the Chipuxet. The Chipuxet Aquifer provides drinking water for the University of Rhode Island (URI) estimated at 12,000 people as well as the Kingston Water District (KWD), with a few more than1,000 accounts. The peak demands on the Chipuxet aquifer fluctuate with the primary users: its largest user URI peaks in fall and spring, while another peak occurs in the summer due to increased water withdrawal by the Kingston Water District. KWD supplies the residential, commercial, industrial, and agricultural water to local users. Private residential wells use groundwater, and turf farms also pump water from the Chipuxet aquifer during the growing season from April through late October. Sewage from water supplied by URI and KWD flows into the Atlantic Ocean, constituting an out-of-basin transfer of water from the Chipuxet Aquifer amounting to 1.317 mgd, (Hershberger et al, 2004). According to the USGS (Wild and Nimiroski 2004) the combined water withdrawals can exceed the river’s capacity.
Flow impacts are also observed in the Hunt River system (Click here to view case study). The Hunt and Annaquatucket Rivers are small coastal streams draining less than 30 square miles each and flowing into Narragansett Bay along the westerly side of Narragansett Bay. The underlying groundwater in the Hunt-Annaquatucket-Pettaquamscutt (HAP) system is found in glacial stratified deposits and is in close hydraulic connection with the surface water system. Three public water suppliers withdraw water from the HAP – the Town of North Kingstown (10 wells), RI Economic Development Corporation for the Quonset Industrial Park (3 wells), and the Kent County Water Authority (1 well). Groundwater is also withdrawn at a privately owned industrial well and at three State-owned wells that provide water to the Lafayette State Fish Hatchery. Extreme low flows have occurred in the lower Hunt during 2005 and 2007 and shifts in fish populations have been documented by RIDEM studies.
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Fig. FW.7.: Flow gauges in Rhode Island (RIDEM, 2007)
In Massachusetts, the Department of Fish and Game’s Riverways Program has developed the pilot River Instream Flow Stewards (RIFLS) to help local groups identify, document and restore rivers and streams suffering from abnormally low flows. Their web site provides information on the flow status of watersheds throughout the state.
According to the RIFLS site the Blackstone River watershed’s capacity for storing freshwater is limited due to small stratified drift deposits for collecting groundwater and limited freshwater wetland areas for storing surface water. For many years, the rivers and streams of the watershed have been dammed to create impoundments to store water for water supply, mill operations and boat passage, particularly during the summer months. The mainstem of the Blackstone receives wastewater from the City of Worcester, much of which originates in the Chicopee and Nashua River basins. Despite this flow augmentation, many sections of the rivers and streams throughout the watershed suffer from unusually low streamflows due to human activity.
Flow in the Blackstone’s Quinsigamond River Basin has been affected by ongoing development and water withdrawals (Blackstone River Coalition, 2008). August monthly flows have declined 55% since 1979. The Quinsigamond River has run dry during parts of the summer in four of the past 10 years.
Low flows have been observed in thirteen streams in the Taunton River watershed. The Canoe River below the Newlands Street Bridge in Norton has severe low flow problems near Well # 3. Stump Brook in Halifax also has recurring low flow problems due to the diversion of water from Monponsett Pond, the brook’s source. Water is diverted to Silver Lake in Kingston to supply the City of Brockton with drinking water. During anadromous fish surveys conducted in the summer of 2002, staff from the Division of Marine Fisheries observed no flow in the Muddy Cove Brook at Hart St. in Dighton, Fall Brook at Glebe St. in Taunton, Sally Richmond Brook at Main St. in Dighton and an unnamed tributary of the Taunton River at Hill St. in Raynham. These streams provide no habitat value for anadromous fish populations when dewatered.
Low flows have also been observed in the Palmer River from the confluence of the East and West Branches of the Palmer River to Route 6 in Rehoboth due to the interbasin transfer of water out of Shad Factory Pond. This water is transferred into the Kickemuit Reservoir in Warren, RI where it is used and distributed by the Bristol County Water Authority.