Nutrient trading is a form of exchange (buying & selling) of nutrient reduction credits. These credits have a monetary value that may be paid to the seller for installing Best Management Practices (BMPs) to reduce nitrogen or phosphorous. In general, water quality trading utilizes a market-based approach that allows one source to maintain its regulatory obligations by using pollution reductions created by another source. As a market-based approach, increased efficiency and cost-effectiveness are achieved by letting the market determine costs. To achieve a desired load reduction, trades can take place between point sources (usually wastewater treatment plants), between point and non-point sources (a wastewater treatment plant and a farming operation) or between nonpoint sources (such as agriculture and urban stormwater sites or systems).