What are trade ratios?
Trade ratios are used to ensure the amount of reduction resulting from the trade has the same effect as the reduction that would be required without the trade. Potential components of a trade ratio include: • Location: the location of the sources in the watershed relative to the downstream area of concern, for example, the Chesapeake Bay; • Delivery: the distance between the buyer and seller if the trade is to meet permit requirements at the outfall; • Uncertainty: the lack of surety of nonpoint source reductions; • Equivalency: the different forms of the same pollutant discharged from the trading partners, such as biologically available phosphorous and bound phosphorous; and • Retirement: additional water quality improvement.
