• Phase II - Water Quality

Potential At-Risk Maps and Information

The following are the proposed model potential at-risk maps produced during the Arkansas Resource Assessment - Phase II. The NRCS definition of the natural resource concern and the input layers and land use designation weights that were used for modeling the natural resource concerns within the Water Quality Degradation Resource Concern are listed to the right of each map. More detailed maps are available by clicking the link below each map.
Excess Nutrients in Surface and Ground Waters
  (View Individual Data Layer Extents)

    NRCS Definition:
        Nutrients (organics and inorganics) are transported to receiving waters
        through surface runoff, leaching into shallow ground waters, or both in
        quantities that degrade water quality and limit use for intended purposes.

    Land Use Designation Weights:
        Pasture (Weight 3); Crop (Weight 2); Urban (Weight 1);
        Forest, Range, Assoc. Agland and Water (Weight 0)

    Binary Input Layers and Associated Weights:
        – SSURGO Flooding Frequency = Frequent (Weight 1)
        – SSURGO Representative Slope >= 3% (Weight 1)
        – Soil Vulnerability Model, Leaching Moderately High or High (Weight 1)
        – Soil Vulnerability Model, Runoff Moderately High or High (Weight 1)
        – Karst, presence of Karst (Weight 2)
        – 303(d) Impairments by 12-digit HUC – Nutrient (Weight 3)

    Classified Input Layers and Associated Weights:
        – Acres of Manure Applied by County (Clipped by Pasture)
                    1 – 8,000 (Weight 1)
              8,236 – 28,339 (Weight 2)
            33,501 – 46,021 (Weight 3)
        – Number of Animal Units by County (Clipped by Pasture)
               803 – 19,715 (Weight 1)
            21,200 – 98,170 (Weight 2)
           129,172 – 185,470 (Weight 3)
        – Acres of Commercial Fertilizer Applied by County
           (Clipped by Pasture and Crop)
            < 78,761 (Weight 0)
            78,761 – 168,948 (Weight 1)
            175,665 – 259,105 (Weight 2)
            270,291 – 349,262 (Weight 3)




Pesticides/Herbicides Transported to Surface
and Ground Waters
  (View Individual Data Layer Extents)

    NRCS Definition:
        Pesticides are transported to receiving waters in quantities that degrade
        water quality and limit use for intended purposes.

    Land Use Designation Weights:
        Crop (Weight 3); Pasture (Weight 2); Forest and Urban (Weight 1);
        Range, Assoc. Agland and Water (Weight 0)

    Binary Input Layers and Associated Weights:
        – SSURGO Flooding Frequency = Frequently (Weight 1)
        – SSURGO Representative Slope >= 3% (Weight 1)
        – Soil Vulnerability Model, Leaching Moderately High or High (Weight 1)
        – Soil Vulnerability Model, Runoff Moderately High or High (Weight 1)
        – Karst, presence of Karst (Weight 2)
        – 303(d) Impairments by 12-digit HUC – Pest/Herbicide (Weight 3)

    Classified Input Layers and Associated Weights:
        – Acres of Herbicide Applied by County
            143 – 44,611 (Weight 1)
            52,227 – 92,711 (Weight 2)
            134,927 – 345,256 (Weight 3)
        – Acres of Insecticide (including Nematicides) Applied by County
            158 – 44,611 (Weight 1)
            50,348 – 93,178 (Weight 2)
            100,390
357,480 (Weight 3)



Excess Pathogens and Chemicals from
Manure, Biosolids or Composts
(View Individual Data Layer Extents)

    NRCS Definition:
        Pathogens, pharmaceuticals, and other chemicals are transported to
        receiving  waters in quantities that degrade water quality and limit use for
        intended  purposes. This resource concern also includes the offsite
        transport of leachate  and runoff from silage, compost, or other organic
        materials.

    Land Use Designation Weights:
        Pasture (Weight 3); Crop (Weight 2); Forest, Range, Urban,
        Assoc. Agland and Water (Weight 0)

    Binary Input Layers and Associated Weights:
        – SSURGO Flooding Frequency = Frequent (Weight 2)
        – Soil Vulnerability Model, Leaching Moderately High or High (Weight 1)
        – Soil Vulnerability Model, Runoff Moderately High or High (Weight 1)
        – SSURGO Depth to Water Table <= 15 (Weight 2)
        – SSURGO Representative Slope >= 3% (Weight 2)
        – Karst, presence of Karst (Weight 2)
        – 303(d) Impairments by 12-digit HUC – Pathogens (Weight 3)

    Classified Input Layers and Associated Weights:
        – Acres of Manure Applied by County (Clipped by Pasture)
                    1 – 8,000 (Weight 1)
              8,236 – 28,339 (Weight 2)
            33,501 – 46,021 (Weight 3)
        – Number of Animal Units by County (Clipped by Pasture)
               803 – 19,715 (Weight 1)
            21,200 – 98,170 (Weight 2)
           129,172 – 185,470 (Weight 3)




Excessive Salts in Surface and Ground Waters
(View Individual Data Layer Extents)

    NRCS Definition:
        Irrigation or rainfall runoff transports salts to receiving water in quantities
        that  degrade water quality and limit use for intended purposes.

    Land Use Designation Weights:
        Crop (Weight 3); Pasture, Forest, Range, Urban,
        Assoc. Ag and Water (Weight 0)

    Binary Input Layers and Associated Weights:
        – SSURGO Taxgrtgrp = Natraqualfs, Natrudalfs or Natrustalfs (Weight 1)
        – Cropped Portions of Southeast AR Groundwater
                                         Salinity Issues (Weight 1)
        – Farmers with Salt Issues (Weight 2)
        – 303(d) Impairments by 12-digit HUC – Salinity (Weight 1)
        – Soil Vulnerability Model, Leaching Moderately High or High (Weight 1)
        – Soil Vulnerability Model, Runoff Moderately High or High (Weight 1)




Petroleum, Heavy Metals, and Other Pollutants Transported to Water (View Individual Data Layer Extents)
    NRCS Definition:
        Heavy metals, petroleum, and other pollutants are transported to receiving
        water sources in quantities that degrade water quality and limit use for
        intended  purposes.

    Land Use Designation Weights:
        Crop, Pasture, Forest, Range, Urban (Weight 1);
        Assoc. Agland and Water (Weight 0)

    Binary Input Layers and Associated Weights:
        – 303(d) Impairments by 12-digit HUC – Metals (Weight 1)
        – Soil Vulnerability Model, Runoff Moderately High or High (Weight 1)
   
    Classified Input Layers and Associated Weights:

        – Oil and Gas Wells - Density per County (30-meter buffer)
                  0 – 0.12% (Weight 1)
            0.122 – 0.45% (Weight 2)
            0.480 – 1.30% (Weight 3)



Excessive Sediment in Surface Waters
(View Individual Data Layer Extents)

    NRCS Definition:
        Offsite transport of sediment from sheet, rill, gully, and wind erosion into
        surface water that threatens to degrade surface water quality and limit use
        for intended purposes.

    Land Use Designation Weights:
        Crop (Weight 3); Forest and Pasture (Weight 2); Range, Urban,
        and Assoc. Ag (Weight 1); Water (Weight 0)

    Binary Input Layers and Associated Weights:
        – SSURGO Flooding Frequency = Frequent (Weight 2)
        – SSURGO Hydrologic Soils Groups B and C (Weight 1)
        – SSURGO Ksat < 0.14 (Weight 2)
        – 303(d) Impairments by 12-digit HUC – Sediments (Weight 4)
        – Model results from the Stream Bank Erosion
                     Natural Resource Concern (Weight 1)
        – Soil Vulnerability Model, Leaching Moderately High or High (Weight 1)
        – Soil Vulnerability Model, Runoff Moderately High or High (Weight 1)

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