Publisher: Center for Watershed Protection
Published: February 2009
Pages: 80

Water Quality Impacts
Stormwater ponds and wetlands are designed and constructed to contain and/or filter pollutants that flush off of the landscape. Without proper maintenance, nutrients such as nitrogen and phosphorus that are typically found in stormwater runoff can accumulate in stormwater ponds and wetlands leading to degraded conditions such as low dissolved oxygen, algae blooms, unsightly conditions and odors. Homeowners adjacent to stormwater ponds and wetlands sometimes complain about these issues. When nutrient concentrations exceed certain thresholds, the trophic state of the system can change. These excess nutrients are often the result of human actions. For example, the amount of fertilizer applied to lawns or the method for disposing of leaves and yard waste in residential and other developed land uses can affect nutrient loads delivered to ponds and wetlands. Excess sediment from the watershed above can also accumulate in wet ponds and wetlands. This sediment can smother the vegetation and clog any filtering structures in the BMPs thereby impacting the overall water quality effectiveness of the stormwater BMP. In addition, standing water in ponds can heat up during the summer months. This warmer water is later released into neighboring waters