National Pollutant Discharge Elimination System Permit Program

As a growing community, Bowie continues to increase the amount of land covered by impervious surfaces. Impervious surfaces do not allow rainwater to filter through the ground where it falls. Instead, the rainwater runs off rooftops and pavement, collecting pollutants and contaminants, and drains into local streams in higher quantities than would occur in a natural environment. Runoff from developed urban areas has been identified as a significant source of pollution in the Patuxent River watershed because it increases the volume and rate of runoff from impervious surfaces, and the concentration of pollutants in the runoff. These components alter the natural hydrology of a watershed and degrade the water quality. The increased water quantity and the decreased water quality result in a variety of problems including habitat modification and loss, increased flooding, decreased aquatic biological diversity, and increased sedimentation and erosion. Effective management of storm runoff protects wetlands and aquatic ecosystems, improves the overall quality of the streams within a watershed, conserves water resources, protects public health, and controls flooding.

The Federal Clean Water Act (CWA) of 1972 established the National Pollutant Discharge Elimination System (NPDES). The primary goal of the CWA was to restore and maintain the chemical, physical, and biological integrity of the nation’s waters. The Phase II Final Rule, published in 1999, requires NPDES permit coverage for stormwater discharges from certain regulated small municipal separate storm sewer systems (MS4s) and construction activity disturbing between 1 and 5 acres. A series of fact sheets describe the various components of the Phase II rule.

The EPA established the Municipal Separate Storm Sewer System (MS4) permit program to specifically control urban stormwater by regulating point sources that discharge pollutants into streams. Point source pollution results from pipes or man-made ditches that directly transport discharge into the local watersheds. Non-point pollution occurs while the rainwater is running over the rooftops and parking lots, collecting the contaminants on or in those materials and depositing them into the streams. In many urban areas, stormwater is channeled by ditches and pipes to drain directly into streams. The stormwater outlets are considered point sources and require MS4 permits.

The Maryland Department of the Environment (MDE) is responsible for issuing all NPDES permits in the state. The primary method to control stormwater discharges is through the use of best management practices (BMPs) that mitigate the environmental impacts of development, runoff quantity and quality, and groundwater replenishment. Stormwater controls and site planning requirements are intended to minimize the impervious surfaces associated with approved land uses, capture and detain runoff peak flows through the implementation of techniques that mimic predevelopment flows to the extent feasible, and reduce pollutants in runoff.

Due to its population, Bowie qualifies as a small MS4 operator. The NPDES program requires small MS4s to develop a stormwater management program that includes six minimum control measures. These control measures are:

The City of Bowie is required to implement the stormwater management program using appropriate stormwater management controls, or integrated best management practices (BMPs). Once streams are polluted or the physical structure and habitat have been altered, it is difficult and expensive to restore it. Therefore, the use of a preventative management system is recommended. BMPs focus on preventing pollutants from ever getting into stormwater. Effective stormwater management is achieved using a systems approach, as opposed to focusing on individual practices as isolated management techniques. Low Impact Development (LID) stormwater management techniques are acceptable BMPs. The EPA has developed the National Menu of BMPs for Stormwater, which the City may incorporate into its stormwater management program. The City is further required to develop measurable goals for the program and to evaluate the effectiveness of the program.

Measurable goals might include pollutant load reduction, stormwater management facility retrofits, and stream restoration. In order to establish these goals, the City will conduct physical habitat assessments and integrate biological and physical monitoring. This monitoring will in turn provide the data to isolate the specific water quality impacts, and will allow the City to estimate the expected pollutant load reductions that may result from implementing a municipal stormwater management program. The data will further define potential project sites for mitigation, restoration or conservation. Retrofitting impervious urban landscapes or existing stormwater management facilities, encouraging Green Building practices, increasing stream buffers and urban forestry efforts are measures that prevent pollution and improve water quality within the watershed.

The data will be included in a detailed Geographic Information System (GIS) that consolidate a variety of information and provide a system for evaluating the effectiveness of the City’s program. GIS data collection will consist of potential pollutant sources, existing storm drain system and storm water management facilities, including LID, as well as potential and/or completed project sites.

Public education and outreach will be implemented through the City’s GREEN Initiatives: Public Information Presentations.