Surface Water - Alabama Department of Environmental Management

Locust Fork (0316-0111)
Sub-Watershed: Slab Creek NRCS Sub-Watershed Number 040
Landuse: The Slab Creek sub-watershed drains approximately 70 mi 2 in Blount and
Marshall Counties. Land cover was an even mixture of forest, pasture, and crop land.
Three current construction/stormwater authorizations, 4 NPDES permits, and 6 CAFO
registrations have been issued in the sub-watershed (Appendix B).
Percent land cover estimated by local SWCD (Appendix A, ASWCC 1998)
Forest Row crop Pasture Mining Urban Open Water Other
38% 20% 31% 1% 7% 4% 1%
NPS impairment potential: Based on local SWCD information, the main NPS concerns in
the Slab Creek sub-watershed were cattle and poultry production, pasture grazing, and crop
runoff (Appendix D). Additionally, Slab Creek was given a 3 rd priority sub-watershed
rating by the Marshall County SWCD for resource concerns including nutrient, pesticides,
and bacteria in surface waters, excessive erosion and sediment from cropland, and
inadequate management of animal waste (Appendix I). The potential for impairment from
urban sources was moderate (Appendix D). Slab Creek was identified as a NPS priority
sub-watershed in 1997 due to impaired habitat quality and biological condition caused by
sedimentation, bank erosion, and nutrient enrichment (ADEM 1999a).
Ratings for each NPS category based on values estimated during the SWCD sub-watershed assessment.
Category
NPS
Score
Animal
husbandry
Aquaculture
Row
crop
Pasture Mining Forestry Sediment
Value 15 1.09 AU/ac 0.00% 20% 31% 1% 16% 2.3 tons/ac/yr
NPS Potential M M L H M L L L
Appendix D H H A A A I I
Assessments: Slab Creek was monitored during ADEM’s 2002 NPS Screening Assessment
(Appendix F). A 2 nd location was monitored during GSA’s Water Quality Asesment of
Locust Fork (Appendix E).
Assessment stations located within the sub-watershed. Descriptions are provided in Appendix E-1.
Station
SLAM-22c
Assessment
Type
Habitat,
Biological,
Chemical
Date Location Area
(mi 2 )
Classification
2002 Slab Cr. at unnamed Marshall CR nr. Douglas 23 F&W
GSA-21 Chemical 1997 Slab Cr. at Marshall CR 39 67 F&W
Slab Creek: At SLAM-22c, Slab Creek is a low-gradient, sand-bottomed stream in the
Southern Table Plateaus (68d) subecoregion (Appendix J). Habitat, biological, and
chemical conditions were surprisingly consistent between the two years. Habitat quality
was assessed as fair (moderately impaired), with sand and silt comprising 80% of the
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