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DEP Home : Water : Stormwater Regulations: NPDES MS4 Permit
For questions about the Montgomery County NPDES MS4 permit, contact DEP:
311Email: AskDEP@montgomerycountymd.gov
The National Pollutant Discharge Elimination System (NPDES) Municipal Separate Storm Sewer System (MS4) Permit Program is an EPA regulatory program administered in Maryland by the Maryland Department of the Environment (MDE). The program is intended to reduce and eliminate pollution from rainfall runoff, which flows through storm drain systems to local streams, ponds, and other waterways. Specifically, the goal of the MS4 Permit program is to restore and maintain the chemical, physical, and biological integrity of the nation's waters, as defined in the Clean Water Act, by controlling previously uncontrolled sources of pollution across the landscape that are transported by rainfall runoff or stormwater.
Learn more about stormwater pollution.
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The Maryland Department of the Environment is responsible for issuing all NPDES permits in the state of Maryland. (The state of Maryland has the authority to issue permits on behalf of EPA.)
DEP is the lead department coordinating a multi-department/agency response to meet the requirements of the stormwater permit issued to the County by MDE. The permit is a key driver of the County's strategic watershed management program. Here are the key permit terms, followed by how the Department of Environmental Protection (DEP) seeks to address them:
DEP programs to meet this requirement include:
For the Anacostia watershed, the County will work to establish a trash pollution baseline within one year, implement a trash abatement program, expand education to citizens, and monitor efforts to ensure that programs continue to progress toward a trash-free Potomac. County-wide programs to meet these challenges include:
Pollutant limits are determined through quantitative analyses referred to as Total Maximum Daily Loads (TMDLs).DEP programs that implement TMDL limits include:
View maps of County watersheds with approved TMDL load limits and County watersheds with Tier II waters (outstanding waters) subject to anti-degradation rules.
DEP programs to identify pollution sources include comprehensive physical, chemical, and biological water monitoring programs.
Environmental Site Design involves managing stormwater on individual development or redevelopment sites in a decentralized manner as opposed to the traditional approach of concentrating stormwater runoff and conveying it through pipes and hardened channels to large-scale, regional ponds or basins. The approach seeks to slow runoff and mimic a site's predevelopment hydrology by using landscaping features and other techniques. DEP's programs to meet this requirement include:
This comprehensive approach to reducing stormwater runoff uses a combination of enhanced planning techniques, alternative permeable covers, vegetative buffers, and small-scale treatment practices to address the impacts associated with development. Programs to meet this requirement include Environmental Site Design/Low-Impact Development.
DEP programs to meet this requirement include code enforcement against illegal dumping and water pollution.
DEP is developing a comprehensive outreach strategy on stormwater education and public involvement. Get involved in the Watershed Restoration Implementation Strategy.
Step 1: Develop a plan within one year of permit issuance (2009-2010).
Step 2: Implement the plan over the 5-year permit term.
Step 3: Collect data and track the results of watershed restoration techniques.
Step 4: Evaluate and modify the plan according to scheduled intervals, using the data collected.
Step 5: Report annually on implementation progress and stream resource improvements.
The Permit requires DEP to submit an annual report to MDE with required report elements (PDF, 2 pp, 16K) on compliance in six areas: