Estimated Total Nitrogen and Total Phosphorus Loads and Yields Generated within States
About this indicator
Excess nitrogen and phosphorus loading impacts not only local waters, but also downstream waterbodies and coastal systems including the Chesapeake Bay, the Great Lakes, the Gulf of America, and Puget Sound. The data in this indicator table are based on output from the United States Geological Survey’s (USGS) Spatially Referenced Regression On Watershed Attributes (SPARROW) models. SPARROW is a watershed modeling tool which, based on a mass-balance approach, estimates the excess amounts (i.e., amounts beyond assimilative capacity) of nitrogen and phosphorus exported from watersheds and delivered to downstream waterbodies. The models relate in-stream water quality measurements of nutrients taken at a network of monitoring stations to spatially referenced attributes of the corresponding watersheds, such as nutrient sources and environmental factors that affect rates of delivery to streams, as well as in-stream processing of nutrients.
| State | Total Nitrogen, Aggregated Yield (kg/km2) | Total Phosphorus, Aggregated Yield (kg/km2) | Total Nitrogen Aggregated Load (kg) | Total Phosphorus Aggregated Load (kg) |
|---|---|---|---|---|
| Alabama | 1,365 | 213.4 | 68,000,000 | 8,830,000 |
| Alaska* | No data | No data | No data | No data |
| Arizona | 20.4 | 5.17 | 6080000 | 1,540,000 |
| Arkansas | 636 | 146 | 87,600,000 | 20,100,000 |
| California | 484.2 | 92 | 124,690,000 | 23,900,000 |
| Colorado | 123.5 | 17.51 | 16,530,000 | 2,310,000 |
| Connecticut | 907 | 107 | 11,700,000 | 1,380,000 |
| Delaware | 1,670 | 106 | 8,880,000 | 565,000 |
| District of Columbia | 4,950 | 226 | 876,000 | 40,000 |
| Florida | 438 | 60.3 | 43,600,000 | 6,000,000 |
| Georgia | 1,097 | 110.4 | 70,580,000 | 7,450,000 |
| Hawaii* | No data | No data | No data | No data |
| Idaho | 420.5 | 69.8 | 43,735,510 | 5,667,258 |
| Illinois | 1,830 | 193 | 267,000,000 | 28,200,000 |
| Indiana | 2,290 | 152 | 215,000,000 | 14,200,000 |
| Iowa | 1,890 | 165 | 275,000,000 | 24,100,000 |
| Kansas | 277 | 57.4 | 59,000,000 | 12,200,000 |
| Kentucky | 974 | 218 | 102,000,000 | 22,800,000 |
| Louisiana | 685 | 188.6 | 52,480,000 | 13,313,000 |
| Maine | 331 | 22.2 | 27,900,000 | 1,870,000 |
| Maryland | 1,763 | 102.6 | 28,458,000 | 1,798,100 |
| Massachusetts | 831 | 53.3 | 17,500,000 | 1,120,000 |
| Michigan | 749 | 41.1 | 113,000,000 | 6,180,000 |
| Minnesota | 746 | 63.8 | 163,000,000 | 13,900,000 |
| Mississippi | 995 | 172.9 | 61,600,000 | 11,010,000 |
| Missouri | 902 | 122 | 163,000,000 | 21,900,000 |
| Montana | 131.7 | 23.26 | 21,360,000 | 5,023,000 |
| Nebraska | 267 | 58.4 | 53,400,000 | 11,700,000 |
| Nevada | 57.4 | 11.33 | 6,517,000 | 862,000 |
| New Hampshire | 385 | 35.2 | 9,260,000 | 846,000 |
| New Jersey | 1,340 | 156 | 26,400,000 | 3,070,000 |
| New Mexico | 30.3 | 5.84 | 5,262,000 | 904,000 |
| New York | 1,912 | 194.9 | 120,600,000 | 13,490,000 |
| North Carolina | 1,158 | 117.9 | 81,890,000 | 8,928,000 |
| North Dakota | 199 | 30.3 | 36,300,000 | 5,550,000 |
| Ohio | 1,740 | 156 | 186,000,000 | 16,700,000 |
| Oklahoma | 238 | 41.2 | 43,000,000 | 7,460,000 |
| Oregon | 290.41 | 41.21 | 58,512,000 | 7,971,000 |
| Pennsylvania | 1,922 | 137.8 | 117,300,000 | 7,820,000 |
| Rhode Island | 1,110 | 162 | 3,230,000 | 471,000 |
| South Carolina | 1,076 | 82.7 | 38,800,132 | 4,090,007 |
| South Dakota | 245 | 34.4 | 49,000,000 | 6,870,000 |
| Tennessee | 1,456 | 275.5 | 91,006,000 | 19,631,700 |
| Texas | 366 | 58.8 | 161,900,000 | 24,370,000 |
| Utah | 85.5 | 14.45 | 10,840,100 | 1,777,000 |
| Vermont | 501 | 44.8 | 12,500,000 | 1,110,000 |
| Virginia | 1,446 | 137.3 | 50,280,000 | 6,370,000 |
| Washington | 363 | 57.8 | 63,300,000 | 10,100,000 |
| West Virginia | 922 | 91.3 | 31,190,000 | 2,822,000 |
| Wisconsin | 822 | 72.5 | 119,000,000 | 10,500,000 |
| Wyoming | 163.3 | 29.77 | 8,780,000 | 2,020,000 |
Note: These data reflect the excess amounts ('loads') of TN and TP generated beyond the assimilative capacity of each states' watersheds.
* Denotes states for which 2012 SPARROW model data were unavailable. Source: USGS' SPARROW Mappers.
Download the Loads data table (xlsx)
Sources of data
Data source information
State-level estimates of TN and TP loads and yields were made as follows:
- USGS 2012 regional SPARROW model outputs for TN and TP aggregated yields (kg/km2) and aggregated loads (kg) were obtained online from the USGS SPARROW Mappers for each of the five geographical regions for which USGS has generated 2012 estimates. Data for 48 states were available; data were not available for Alaska or Hawaii.
- Some states had data presented across multiple regional Mappers, however the areas of the state presented in each Mapper were unique and not represented in the other regional Mappers. The data from multiple Mappers for the same state were added together to show one complete picture for the whole state.
What to Consider When Using These Data
The 2012 SPARROW models rely on a base year of 2012, which means the models were developed based on source inputs and management practices similar to those existing during or near 2012 and average hydrological conditions detrended to 2012 (2000–14).
Note: The 2002 SPARROW data have been removed from this webpage due to differences in the data quality and approaches between the 2002 SPARROW models and updated 2012 SPARROW models that do not allow for direct comparisons. In developing the 2012 SPARROW models, several updates and improvements were made to the data inputs and statistical approaches used to calibrate/develop the models from those used in the previous 2002 SPARROW models.