Tables: Regional and Municipal Stormwater Management Plans
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1. Table 3-1: Pollutant Loads by Land Cover
BMP 2026, Ch 3, p. 25
| Land Cover |
TP load (lbs/acre/yr) |
TN load (lbs/acre/yr) |
TSS load (lbs/acre/yr) |
| High, Medium Density Residential |
1.4 |
15 |
140 |
| Low Density, Rural Residential |
0.6 |
5 |
100 |
| Commercial |
2.1 |
22 |
200 |
| Industrial |
1.5 |
16 |
200 |
| Urban, Mixed Urban, Other Urban |
1.0 |
10 |
120 |
| Agriculture |
1.3 |
10 |
300 |
| Forest, Water, Wetlands |
0.1 |
3 |
40 |
| Barren Land/Transitional Area |
0.5 |
5 |
60 |
Source context and notes
Source revision: January 2026.
municipality. Pollutant loads are required for each HUC14 in the municipality. For each land use within the HUC14, multiply the total acreage by the assigned load factor, which is given in pounds per acre per year.
The total pollutant load for the HUC14 will be the sum of the loads for each land use.
Table 3-1: Pollutant Loads by Land Cover
| Land Cover | TP load (lbs/acre/yr) | TN load (lbs/acre/yr) | TSS load (lbs/acre/yr) |
| --- | --- | --- | --- |
| High, Medium Density Residential | 1.4 | 15 | 140 |
| Low Density, Rural Residential | 0.6 | 5 | 100 |
| Commercial | 2.1 | 22 | 200 |
| Industrial | 1.5 | 16 | 200 |
| Urban, Mixed Urban, Other Urban | 1.0 | 10 | 120 |
| Agriculture | 1.3 | 10 | 300 |
| Forest, Water, Wetlands | 0.1 | 3 | 40 |
| Barren Land/Transitional Area | 0.5 | 5 | 60 |
Note: References for Table 3-1 are provided at the end of this chapter.
The build-out analysis can go further than the requirements in the regulations. In addition to pollutant loads and impervious surfaces, the analysis can be used to assess open space plans and to project school population and demand on municipal services. The build-out analysis can greatly benefit a municipality by envisioning its future so that steps can be taken to prevent unwanted impacts or plan for future needs. Finally, the build-out analysis should include a summary with critical findings, conclusions and recommendations.
It is important to note that, although the pollutant loads for agricultural lands are higher than those for low density residential for the parameters in Table 3-1, converting agricultural lands to residential use typically results in an increase in pollutant loads for metals and petroleum hydrocarbons; it is recommended that each municipality calculate build-out pollutant loads for each. Although the total load of suspended solids from stormwater runoff may decrease by the conversion of agricultural lands to low density residential use, the percentage of impervious cover increases dramatically. If the additional stormwater runoff peak flow rates caused by additional impervious are not managed properly, these higher flow rates will increase stream bank erosion, thereby increasing sediment loads to the receiving waters.