Total Phosphorus, Total Nitrogen, and Total Suspended Solids in Runoff


One function provided by wetlands systems, as well as by other Stormwater Management/Best Management Practices (SWM/BMPs), is improved water quality through treatment of stormwater runoff. Nitrogen (N), phosphorus (P) and sediments are typically the primary pollutants of concern, although a range of organics, metals and salts also pose issues in certain heavy urbanized/industrial areas. Typically, the effectiveness of this water treatment function is evaluated by determining the pollutant load reduction from flow through the wetland/stream and/or BMP system. The first element of this calculation is the estimation of pollutant loading, which typically is [i.e. Virginia Runoff Reduction Method (VRRM)] accomplished using the Event Mean Concentration (EMC) of the subject pollutant which is currently set at 0.26 mg/L of total-P (TP) in Virginia. This value has been unchanged since its derivation from the 1980-81 Nationwide Urban Runoff Program (NURP) study.

The basic issue and associated research question here is whether or not the combination of Clean Air Act implementation and a state law restricting the use of phosphorus lawn fertilizer has reduced the EMC of TP in stormwater runoff in Virginia. The program is also addressing TN and sediment losses in the monitored systems. This project is being conducted by Virginia Tech. The project is also receiving matching funding from the Virginia Tech Foundation provided by Dr. Buck Cox, a private citizen.

Request for Proposals

Amount awarded: $100,000

Research Reports