Filtering Fertilizers and Pet Waste
- Runoff commonly contains pollutants such as excess nitrogen and phosphorous that collect from lawn fertilizers and pet waste. Trees have been shown to filter up to 80% of phosphorus out of stormwater, preventing it from reaching waterways.
- Established trees with developed root systems in bio-retention practices have been shown to reduce nitrogen loading by approximately 50% and phosphorus loading by 75%.Bratieres K, Fletcher TD, Deletic A, Zinger Y, 2008, Nutrient and sediment removal by stormwater biofilters: A large-scale design optimization study, Water Research, 42: 3930-3940.
Riparian Buffers
- Maintaining a 50’ strip of undisturbed forest along urban streams is a good practice. Forested riparian buffers along streams have been shown to consistently reduce nitrate concentrations in streams by 75%.Wenger, S (1999). A review of the scientific literature on riparian buffer width, extent, and vegetation.