2. Development of BMP Cost-Effectiveness Values
calculations, we assume that the reported cost-share figures represent 75% of
the total cost of the practice. Unless otherwise noted, the sources for
related data are as follows:
NCDSW C (1994)
Soil Conservation Service (SCS)
Operation and maintenance costs
North Carolina State
The costs used in this analysis are the sum of dollars spent between 1985 and
1994, The figures were not corrected for inflation and therefore do not represent
1994 dollars. This introduces a level of error into the analysis. Correcting for
inflation requires a yearly break down of total cost-share costs, by practice, in the
Tar-Pamlico basin. This information is not currently available, but may become
available in the future.
Sources of BMP Effectiveness Data
We have used various sources for estimating the nutrient reduction effectiveness
For each practice, the relevant literature was evaluated
and the most geographically relevant and up-to-date studies were chosen as the
basis for our estimates.
For animal waste management practices and water control structures,
effectiveness data were available from studies conducted in (or very near to) the
Tar-Pamiico basin. These studies were primarily carried out through the North
Carolina State University and the North Carolina Cooperative Extension Service.
effectiveness in the Tar-Pamlico basin were not
Studies on conservation
We therefore chose to use results from modeling studies conducted in
the Chesapeake Bay basin (Casman, 1990; Camacho, 1990; Camacho, 1992).
The Tar-Pamlico basin and the Chesapeake basin can differ substantially in
terms of important environmental conditions, such as climate, topography and
soil type. However; a portion of the Chesapeake basin contains the two
ecoregions which comprise the Tar-Pamlico basin (Ecoregion 63, Middle Atlantic
Coastal Plain and Ecoregion 65, Southeastern Plains). Ecoregions are areas
classified as generally similar-m terms of land surface
soils, land use, and
potential natural vegetation (Omemik, 1986). Twenty-three of the 63
Chesapeake Bay modeling subbasins are located within the Middle Atlantic
Coastal Plain and Southeastern Plains ecoregions.