Surface Water - Alabama Department of Environmental Management

Methodology
Assessment of Mulberry Fork (Shepard et al. 2001, Shepard et al. 2002), and the University
Tributary Nutrient Loading Project (Appendix S). Evaluated assessments have been
conducted in conjunction with ADEM’s ALAMAP Program (Appendix T). A summary of
6 of these projects, including lead agency, project objectives, type of assessments
conducted and data collected, and applicable quality assurance manuals, is provided in the
appendices.
Other data/information: ADEM’s municipal, industrial, mining, and CAFO databases
were reviewed to eliminate sub-watersheds primarily impacted by point sources or
monitored in conjunction with NPDES permits (ADEM 2002g, 2002h). Biological and
chemical data were also reviewed to locate sampling reaches in areas that had not been
recently assessed.
Landuse: ADEM assigned each sub-watershed an NPS rating based on estimates of
landuse percentages, animal populations, and sedimentation rates to prioritize subwatersheds
for assessment and to identify potential sources of impairment. These
estimates were obtained from information provided to ADEM by the Alabama Soil and
Water Conservation Committee (ASWCC) and local Soil and Water Conservation Districts
(SWCD). This information was provided on Conservation Assessment Worksheets
completed in 1998 (FY97 CWA § 319 Workplan Project #4). Sub-watershed assessment
information is available at www.swcc.state.al.us.
Additional landuse information was obtained from estimates of percent land cover for
the entire southeastern U.S. published by EPA (EPA 1997b). These estimates were based
on leaf-off Landsat TM data acquired in 1988, 1990, 1991, 1992, and 1993. Recent
ground-truthing of these estimates have indicated 58% accuracy due to a decrease in
agricultural use and an increase in plantation pine in some areas of Alabama within the last
10 years (Pitt 2000). Use of these estimates to locate least-impaired ecoregional reference
sites in Georgia has indicated an accuracy of 40-60% (Olson and Gore 2000). Therefore,
only the conservation assessment worksheets were used to evaluate potential for
impairment from nonpoint sources. The EPA Landsat data was provided in ADEM 1999a.
Animal population estimates: The potential NPS impairment from activities associated
with animal husbandry was assessed. The impairment potential among the different animal
types was standardized by converting animal populations into animal units (AU). Animal
unit estimates were calculated for each of the animal types based on the current conversion
factors found in ADEM Administrative Code Chapter 335-6-7 (Table 8). These values
considered characteristics such as live weight equivalent waste quantity and constituent
composition (limiting nutrients, moisture, additive compounds, etc.) (ADEM 1999b). AU
estimates for each animal type were further standardized by converting to animal unit
densities (AU/acre of sub-watershed).
Forestry practices: Where the information was available, 3 categories were summed to
assess the potential for impairment from forestry practices: percent of acres clear-cut,
percent of acres harvested annually, and percent of forest needing improvement. This
information was provided by the local SWCD and the Alabama Forestry Association.
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