Land-Based Measures of BMP Performance
ASABE Annual International Meeting , 2010
Yagow, G., Benham, B., Ling, E.J.
Typically, the effectiveness of agricultural and forestry BMPs is evaluated based on instream measurements of nutrients and sediment. However, as can be seen from the wide range of reduction efficiencies attributed to any BMP from published research, a large number of climatic, fate, and transport variables often obscure cause and effect relationships and the exact mechanisms responsible for load reduction. In-stream pollutant reductions from BMP implementation are also typically not immediate, but gradually accrue over time as vegetative BMPs mature, or while BMPs reduce nutrient build-up in the soil or bacteria attached to channel sediments. Because of these uncontrolled variables and time lags between BMP implementation and pollutant reduction, BMP performance efficiencies are difficult to evaluate. This paper summarizes the results of a white paper to quantify BMP performance based on landbased, rather than in-stream, measures in an attempt to identify interim measures of BMP performance that could assist in better evaluating project progress for short-term (1-2 years) projects that do not include funding support for monitoring and lab analysis of water quality samples. Three categories of metrics were identified for 15 BMPs: site selection, performance over time, and maintenance, with the emphasis in this paper on the performance metrics. The intent is to eventually relate these interim measures with in-stream water quality measures, so that they can serve as useful surrogates to guide implementation and to ensure long-term sustainability of implemented BMPs, even after practice life or project periods end.