Swift Creek Reservoir & Watershed
The Swift Creek Reservoir was constructed in 1965 as a public water supply for Chesterfield County. The 12 million gallon per day capacity Addison-Evans Water Treatment and Laboratory Facility provides on average 7.5 million gallons per day of drinking water to the county. The reservoir is a 1,700-acre impoundment containing approximately 5.2 billion gallons of water.
The Swift Creek Reservoir watershed is located in the northwest part of the county and encompasses 61.9 square miles. Its headwaters are located in Powhatan County. The watershed is divided into the following subwatersheds, based on its tributary streams:
- Dry Creek
- Fuqua Creek
- Horsepen Creek/Blackman Creek/Deep Creek
- Little Tomahawk Creek
- Otterdale Creek
- Tomahawk Creek
- Turkey Creek/Swift Creek
- West Branch
Chesterfield County conducted an assessment of the conditions of the Swift Creek Reservoir Watershed in 1989. Three years later, the Board of Supervisors adopted goals to protect the Swift Creek Reservoir and established a Watershed Management Committee that included citizen and staff representatives. This committee was charged with identifying strategies and alternatives to protect the reservoir.
Based on recommendations from the committee in 1997, the Board established through ordinance, a phosphorus loading limit of 0.22 pounds per acre per year for new residential development and 0.45 pounds per acre per year for nonresidential development. These loading limits were established by setting a 0.05 milligrams per liter in-lake phosphorus limit and calculating an allowable annual phosphorus input load.
Regional Master Plan
The Board also directed staff to prepare a regional master plan that included a funding strategy requiring the development community to fund the construction of regional facilities. Additionally, development within the watershed was to fund the maintenance of the regional facilities.
In 2000, the Board unanimously approved the regional master plan called the Watershed Management Master Plan and Maintenance Program. The Watershed Master Plan was developed to meet the goals and strategies set forth in Watershed Management Plan of 1996 through the construction of a system of regional storm water treatment facilities. One of these facilities, the regional in-stream pond component, was to provide the greatest reduction of pollutants.
In-Stream Regional Ponds
In January 2006, the use of regional in-stream ponds met with resistance from federal regulatory agencies. During a meeting with the regulatory agencies, staff was advised that the in-stream regional pond component would not receive permitting and any future regional facilities would require off-line construction.
Storm water pollution is directly related to the amount of impervious surface within a development. The reason for this is conventional storm water controls use these areas to collect, concentrate and convey storm water prior to discharge to a waterbody. Reducing impervious surface reduces the amount of runoff and limits the pollutant concentration resulting in the protection of county waters and the reservoir. The following will aid in reducing impervious surface starting with a review of existing county ordinances:
- County Ordinances (Site Plan and Subdivision): A preliminary review of county ordinances has identified several ordinances which could assist in the reduction of pollutant loads from new development. A more comprehensive review of the county's ordinances will be conducted to determine those areas where modifications may help to improve storm water runoff.
- Preservation and Restoration of Natural Cover and Areas: Retaining the existing natural conditions such as vegetation, soils and wetlands provide a natural and cost effective way to manage storm water quantity and quality.
- Low Impact Site Design Techniques: LID is a site design strategy with the goal of maintaining or replicating the pre-development hydrologic regime through the use of design techniques to create a functionally equivalent hydrologic landscape.
- Utilization of Natural Features for Storm Water Management: Traditional storm-water systems are designed to collect, concentrate and convey storm flows efficiently away from the development. Natural drainage patterns tend to be ignored and replaced with structural controls. A nontraditional approach would seek to incorporate the sites existing natural features. These could include natural drainage patterns, depressions, permeable soils, wetlands and vegetative areas. This would reduce the number of structural controls and provide for more natural storm water control of infiltration, pollutant filtration and maximize on-site storm water storage.
These measures will help to minimize the pollutant loads from future development by controlling the pollutants at the source. That portion of the future loads which can not be reduced as part of the on-site treatment and is in excess of the target load limit is referred to as the orphan load. The reduction of load will need to be addressed through county run projects. The program will be executed through funds collected as part of the pro-rata fees. Many of these projects will be regional in nature and aimed at reducing identified pollutants loads.