Publication Date
4-8-2008
Abstract
The Massachusetts Water Management Act (WMA), administered by the Massachusetts Department of Environmental Protection (MassDEP), was enacted in 1985 and requires regulation of water withdrawals above a threshold volume of 100,000 gallons per day. After an initial registration period between 1981 and 1985 for water users withdrawing over the threshold volume, permits were required for existing users that had increased water use or added new sources, and new users above the threshold volume. In its review and issuance of permits, MassDEP must consider the environmental impact of proposed withdrawals, including the impact on the safe yield of the water basin. WMA Regulations 310 CMR 36.00 previously included a specific methodology for calculating basin safe yield that was later found to inadequately balance the competing water needs of humans and the environment. MassDEP, recognizing the problems in the original basin safe yield calculations and with increasing concern over low streamflows in the Ipswich River Basin, contracted with the U.S. Geological Survey (USGS) to conduct a number of hydrologic assessment reports between 2000 and 2004 in the Ipswich River Basin. These studies confirmed that water withdrawals were having a significant impact on streamflow in the basin. One of these reports, which focused on habitat and streamflow requirements for the basin, indicated that the decreased flow regime observed in the basin caused a shift in the fish community structure from cold-water fluvial fish to warm water generalist species. In response to these studies, MassDEP modified the permits issued in the Ipswich River Basin to include a number of conservation measures, including the condition that nonessential outside water uses, in particular, lawn irrigation, cease when streamflows reach specific levels identified in the USGS reports. Recently the Department of Conservation and Recreation has developed index streamflows for Massachusetts based on a USGS report that identified the least impacted streamflow gaging stations within southern New England. The index streamflows provide information specific to Massachusetts watersheds that can be used to assess near natural flow conditions. This data supplements the U.S. Fish and Wildlife Service’s Aquatic Base Flow values that are representative of the greater New England area. Use of the index flows in WMA permitting policy will allow MassDEP to further the goal of balancing competing water needs and uses by requiring outside water use restrictions triggered by index streamflow values that are more pertinent to Massachusetts streams.