Citation:

Chamberlin, C., K. Munson, M. TenBrink, A. Le, AND N. Detenbeck. Connecting ecosystem ecology and regional planning: A case study for reducing nutrient loading to the Long Island Sound. Ecological Society of America 2021: Vital Connections in Ecology, NA, Virtual, August 02 - 06, 2021.

Impact/Purpose:

Pollution by excess amounts of nitrogen and phosphorus causes water quality problems such as nuisance algal blooms in many waterbodies around the nation and world. Nitrogen and phosphorus enter waterways from agricultural areas through the use of fertilizers, from urban areas through stormwater runoff, from Waste Water Treatment Plants, and from numerous other sources. Best management practices exist to reduce the amount of nitrogen and phosphorus entering rivers, however implementing these practices can be expensive. This project considers the Upper Connecticut River Basin in Vermont and New Hampshire and seeks to reduce the amount of nitrogen and phosphorus flowing into the Lower Connecticut River for the least amount of money. To do this, we used data describing (1) where in the watershed nitrogen and phosphorus are entering the river system, (2) what the costs are of agricultural and stormwater best management practices, (3) the efficiency with which these best management practices remove nitrogen and phosphorus from water entering streams, and (4) the costs and removal efficiencies of upgrading Waste Water Treatment Plants in the watershed. We found that reducing the export of nutrients by 10% will cost ~$20,000,000/year, and can be accomplished through a combination of Waste Water Treatment Plant upgrades and implementing both stormwater and agricultural best management practices. We also develop a support tool that is capable to performing similar analyses for other watersheds in the northeast.

Description:

Excess loading of nitrogen and phosphorus to the nation’s waters has had devastating impacts on downstream lakes, estuaries, and coastal zones. The Long Island Sound is one such waterbody that suffers from low dissolved oxygen and excessive algal blooms due to nutrient loading from surrounding areas. Here we present results of work performed with stakeholders in the Upper Connecticut River to help them meet their current and potential future obligations for nutrient reduction through the Clean Water Act. The Upper Connecticut River is a 16,000 km2 watershed, of which 5% is urban land, 2% is in row crop, and the remainder is primarily forested land with some hay fields. The nutrient inputs to the watershed are varied, and reductions in loading may be accomplished by upgrades to Waste Water Treatment Plants or through combinations of Best Management Practices (BMPs) for urban and agricultural land. We combined published estimates of nutrient inputs from spatially resolved water quality models, estimates of BMP nutrient reduction efficiencies based on hydrologic-hydraulic models, and regional and national cost analyses to create an optimization model that identifies a suite of BMPs that will reduce annual loading from the watershed for the least financial cost to stakeholders. We find that for the Upper Connecticut River, simultaneously meeting three loading targets in the watershed can be accomplished through a combination of agricultural and urban BMPs, upgrades to Waste Water Treatment Plants, and the creation of riparian buffers along a fraction of river banks. The total annualized cost of these improvements is ~$20,000,000 /year. We use the results of this case-study to develop a support tool application that can be used to perform similar analyses in other river basins in the northeast.

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