Quenching Growth Demands:
Policies to Avoid Regional Water Supply Shortages as Residential Development Increases in Narragansett and South Kingstown, Rhode Island

Katherine Wallace
Bachelors of Arts in Environmental Studies
May 2003

The northeastern United States is traditionally considered a water-rich region, and Rhode Island has been no exception in the past. Mean annual precipitation in the Ocean State is considerably higher than elsewhere in the nation. Therefore water conservation, allocation, and prioritization of uses has never been a serious consideration in the state. However, awareness is growing of the necessity to better manage water resources in order to avoid shortages especially after the 2002 drought. Consistent with this, my thesis asks the question: Are regulatory and/or growth management measures necessary to avoid regional water supply shortages as residential development increases? In order to answer this, I also asked (1) are shortages a serious consideration at present and in the future and (2) if so, what regulatory, growth management, and governance issues are necessary to ensure that water supplies can meet demand.

Water shortages occur when demand exceeds supply. Consequently it is necessary to quantify current and future supply and demand in order to determine whether a shortage is pending. Water use and availability varies greatly throughout Rhode Island despite it being the smallest state. Therefore rather than evaluating supply and demand throughout the state I conducted case studies of the towns of South Kingstown and Narragansett, Rhode Island. My methodology to research these areas involved reviewing current studies and articles related to water shortages, participating in the Rhode Island Water Resources Board water allocation program development process, conducting GIS analysis of demographic trends, water sources, and existing infrastructure, reviewing documents submitted by municipalities and water districts related to water supply and growth management, and conducting semi-structured interviews of federal, state, municipal, and water district staff.

South Kingstown and Narragansett share a common history, common economic and demographic characteristics, and a common water supply. They have among the highest population growth rates in Rhode Island. South Kingstown contains multiple groundwater reservoirs, but due to soil constraints Narragansett has no sources of potable water. Therefore Narragansett almost completely depends on South Kingstown for its water supplies, and both towns are increasingly being served by one groundwater source, the Mink Aquifer.

The Rhode Island Water Resources Board requires that water district withdrawals are less than the safe yield of the water supply. However, methods for calculating safe yield for groundwater supplies do not adequately reflect the sustainable capacity of aquifers. I propose that safe yield for groundwater resources should be a function of the annual recharge of the aquifer. I estimated the annual recharge volumes for years with varying precipitation and compared it to reported and projected demand scenarios. I found that withdrawals are exceeding supplies during critical dry periods and will increasingly do so in the future. Projected demand scenarios for 2019 as currently reported and including additional expected wholesales surpass recharge values during years with mean annual precipitation by 10.7% and 39.7%, respectively. This violates the state's principle that withdrawals may not exceed the safe yield of the resource.

In order to avoid regional shortages, supply must be better quantified by further hydrogeologic investigations and streamflow monitoring. This requires funding, so water users should pay impact fees and user surcharges to fund water availability studies and to raise awareness of the value of water. Coordination among water suppliers, municipalities, and state agencies must also be enhanced to ensure that growth policies account for available water supplies. Better knowledge of supply and uniform reporting of actual and projected demand will facilitate more effective management by water districts, municipalities, and the state.