there are different methods to determine if a bioswale needs maintenance. bioswales are benchmarked to meet a specific level of infiltration to determine if maintenance is required. a staff gauge is used to measure the infiltration rate. soil chemistry testing is also required to determine if the soil has a certain off-level of any pollutant. phosphorus and high levels of salinity in the soil are two common pollutants that should be attended to. analysis of inflow and outflow pollutant concentration is also another way to determine the performance level of bioswales.