Stormwater Benchmarks: U.S. EPA Benchmarks of Acceptable Ranges

Update: Numeric Action Limits (NALs) are now used in place of Benchmarks. NAL exceedances result in Level I or Level II designation and additional reporting to Regional Board.

Learn More about Numeric Action Limits (NALs)

U.S. EPA Benchmarks of acceptable ranges:

Parameter Name EPA Benchmark:
Acceptable Range
pH 6 to 9
Total Suspended Solids Below 100 mg/L
Specific Conductance Below 200 umhos/cm
TOC Below 100mg/L
Aluminum Below 0.75 mg/L
Zinc Below .117 mg/L
Iron Below 1.0 mg/L
Copper Below 0.0636 mg/L
Lead Below 0.0816 mg/L
COD Below 120 mg/L
Nitrogen Ammonia Below 19 mg/L
Nitrate + Nitrite Total Below .68 mg/L
BOD Below 30 mg/L

Note: Your storm water runoffs should comply with EPA benchmarks. However, Regional Water Boards may require different values than those adopted by the EPA. Stormwater Benchmarks.