Stormwater is the water running off developed areas during and shortly after rain. If it is muddy, has a film on it, or smells bad, it likely contains something other than what fell from the sky as rainwater. In fact, even if it is clear with no odor, it could still contain excess nutrients from a recent application of fertilizer, as well as residual herbicides or insecticides applied to plantings. The increased quantity and speed of water running off can also adversely impact stream channels, cause flooding, and limit groundwater recharge.
The primary method to control stormwater discharges during construction is by regulating the erosion. In Carrboro, this program has been delegated to Orange County to implement. The primary method to control stormwater discharges after construction is through the use of "stormwater control measures", or SCMs. There are a variety of SCMs that include "structural" approaches such as ponds (wet and dry), wetlands, permeable pavement, cisterns, green roofs, and rain gardens as well as "nonstructural" approaches such as Low Impact Development (LID), impervious disconnection, street sweeping, illicit discharge detection and elimination, and fertilizer management. Low Impact Development is a voluntary approach to stormwater management that can reduce infrastructure costs, increase lot values, and enhance water quality protection. LID is being encouraged at the State level through a new policy and tools.
Much of Carrboro was developed before stormwater was regulated. Retrofitting existing development is more expensive and difficult than planning for stormwater mitigation during new development. Nevertheless, when it comes to helping reduce the impacts of stormwater on our properties, creeks, streams, and rivers, there is a lot we all can do.