Figure 1.1

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EXPLANATION

[>, greater than; ≤, less than or equal to]

Nitrogen concentration, in milligrams per liter

0 to 0.25
>0.25 to 0.5
>0.5 to 0.75
>0.75 to 1
>1 to 2
>2 to 3
>3 to 4
>4 to 5
>5 to 6
>6

Nitrogen yield, in kilograms per square kilometer

0 to 5
>5 to 15
>15 to 30
>30 to 75
>75 to 150
>150 to 250
>250 to 350
>350 to 550
>550 to 1,000
>1,000

Nitrogen benchmark, in exeedance of EPA NRSA regional criteria

Near-reference
>1 to 2
>2 to 4
>4 to 10
>10

Phosphorous concentration, in milligrams per liter

0 to 0.02
>0.02 to 0.05
>0.05 to 0.07
>0.07 to 0.1
>0.1 to 0.15
>0.15 to 0.25
>0.25 to 0.35
>0.35 to 0.5
>0.5 to 0.85
>0.85

Phosphorous yield, in kilograms per square kilometer

0 to 0.5
>0.5 to 2
>2 to 6
>6 to 10
>10 to 15
>15 to 25
>25 to 40
>40 to 70
>70 to 120
>120

Phosphorous benchmark, in exeedance of EPA NRSA regional criteria

Near-reference
>1 to 2
>2 to 4
>4 to 10
>10

Sediment concentration, in milligrams per liter

≤2
>2 to 5
>5 to 10
>10 to 20
>20 to 30
>30 to 40
>40 to 85
>85 to 100
>100 to 200
>200

Sediment yield, in metric tons per square kilometer

≤2
>2 to 5
>5 to 10
>10 to 20
>20 to 30
>30 to 40
>40 to 85
>85 to 100
>100 to 200
>200

Total nitrogen concentration — 2012 SPARROW simulated total nitrogen concentration, in milligrams per liter

Total phosphorus concentration — 2012 SPARROW simulated total phosphorus concentration, in milligrams per liter

Total nitrogen accumulated yield — 2012 SPARROW simulated total nitrogen accumulated yield, in kilograms per square kilometer

Total phosphorus accumulated yield — 2012 SPARROW simulated total phosphorus accumulated yield in kilograms per square kilometer

Total nitrogen concentration exceedance — SPARROW total nitrogen concentration exceedance of U.S. Environmental Protection Agency (EPA) National Rivers and Streams Assessment (NRSA) regional criteria

Total phosphorus concentration exceedance — SPARROW total phosphorus concentration exceedance of U.S. Environmental Protection Agency National Rivers and Streams Assessment regional criteria

Suspended-sediment concentration — 2012 SPARROW simulated suspended-sediment concentration, in milligrams per liter

Suspended-sediment accumulated yield — 2012 SPARROW simulated suspended-sediment accumulated yield, in megatons per square kilometer

Figure 1.1. SPAtially Referenced Regressions On Watershed (SPARROW) model results for nitrogen, phosphorous, and sediment in the conterminous United States. Map derived from figures 3, 4, and 8.

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