Managing Watersheds from Town Hall

Lorraine Joubert, Water Resource Specialist
URI Cooperative Extension
Department of Natural Resources Science

Lorraine Joubert developed and oversees the Municipal Watershed Training Program, which provides technical assistance and education to municipal officials on nonpoint pollution control and community-based watershed assessment. She works with communities to assess the cumulative impacts of watershed land use and to incorporate environmental risk into land-use decisions.

Research on the sources, fate, and effects of pollutants in coastal watersheds provides valuable insights to better manage coastal watersheds. But the real breakthroughs in protecting estuarine water quality take place outside the field and lab and inside town hall at the monthly meetings of the local planning and zoning boards. Local officials are key to managing local water quality by updating comprehensive plans, approving zoning changes, and reviewing subdivisions. Through these routine decisions, they can dramatically reduce the risk of pollution to coastal waters. Town planners, council members, and volunteer board members have a new resource to help them in their decision making: research results distilled in a format that they can readily use, and watershed assessment tools using computer-generated maps to target high-risk locations for pollutant movement.
      Through the Municipal Watershed Training Program, URI faculty, Cooperative Extension water quality specialists, and student interns provide scientific expertise to help community leaders reconcile population growth and development demands with water resource protection goals (Watershed Assessment at URI). A new tool used in this work is the Cooperative Extension's model for assessing watersheds, the Method for Assessment, Nutrient Loading and Geographic Evaluation of watersheds (MANAGE), which is used by URI staff in conjunction with community leaders. (See Watershed Assessment at URI) URI Cooperative Extension staff provide Geographic Information System (GIS) skills and expertise in watershed management science. In turn, town representatives and citizens share their knowledge about local land use to enhance map data, select future land-use scenarios for analysis, and decide how the results will be used to protect or restore local water quality. The assessment process takes place in a series of four or five meetings between a small group of town representatives and Cooperative Extension staff. This provides an opportunity for local participants to comment on draft results and guide the assessment. The local group also decides how the results will be shared with other town officials and the public. Most importantly, the local committee suggests realistic management actions the town can take to better protect or restore local resources based on the assessment findings.
      MANAGE is a watershed assessment tool that uses computer-generated maps to take a first-cut look at pollution risks posed by land use and landscape features. Designed as a system to support land-use decision making, MANAGE identifies sources of pollution to watersheds and groundwater aquifers. By analyzing maps, summarizing watershed characteristics, and estimating nutrient sources, MANAGE compares the effect of future land-use patterns on local water resources and evaluates the effectiveness of stormwater and wastewater management practices in reducing pollution risk.
      The primary source of data used for assessment is the Rhode Island Geographic Information System (RIGIS), an extensive, high-resolution database available to Rhode Island communities. MANAGE accesses the RIGIS database through the URI Environmental Data Center. To predict how continued development might affect water quality, we must have data on soil types and land use. We can then map future land use showing full development based on town zoning or land-use planning. This allows town officials to envision the effect of future growth and to identify the type and location of potential pollution threats.
      MANAGE generates three types of assessment results: pollution source hotspot mapping, a rapid screening of potential high-risk areas; watershed indicators that measure generalized ecosystem health based on soil and land-use characteristics; and a nutrient loading component that incorporates the results of research on the sources and fates of nitrogen. It generates a hydrologic budget with which to compare alternative development scenarios.
      All three types of results give town officials a way to target limited resources and control the most serious pollution risks. Hotspot mapping is most effective in allowing decision makers to visualize problem sites. The initial premise is that high-intensity land uses are more likely to generate pollutants than less intensive uses. The probability that pollutants generated will actually reach groundwater or flow into nearby streams and ponds depends on soils and proximity to receiving waters.
      MANAGE uses soil permeability and water table depth data to locate areas where rainwater and accompanying pollutants are likely to either seep into the ground or run off the surface to nearby wetlands and streams. These hydrologically active soils reveal pathways of water and pollutant movement via groundwater recharge or by direct flow through surface drainage networks. Wet soils with high groundwater are not isolated in the landscape but are connected to small headwater streams and wetlands in an extended drainage network. Maintaining this drainage network preserves natural pollutant removal functions, promotes infiltration, and protects the water quality of downstream waters.
      The MANAGE hotspot analysis combines high-intensity land use and high-risk soil features to screen hotspots where pollutants are typically generated and where offsite movement is also likely. In the hotspot mapping example, high density, unsewered residential development, commercial land use, and active cropland are overlaid with soils having a shallow water table, revealing potential hotspots for stormwater runoff and septic system failure. Additional map analysis can highlight risks to groundwater in very sandy soils where pollutants can move unimpeded into aquifers, in shoreline areas that have lost protective forest cover, and areas where soils are easily eroded. Targeting hotspots efficiently narrows potential problem areas for follow-up field investigation, focused public education, or pollution remediation.

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