San Diego Region - San Diego Municipal Storm Water Permit - Frequently Asked Questions
- What is a Municipal Separate Storm Sewer System (MS4) Permit?
- What do the Federal Regulations require?
- What exactly is a Municipal Separate Storm Sewer System (MS4)?
- What are the basic requirements of the storm water program?
- Do MS4 Permits prohibit activities at my house or business?
- Can I wash my car?
- Can I water my lawn?
- Do MS4 permits regulate the use of pesticides, herbicides, and fertilizers?
- Can I wash my patio or driveway?
- What should I do if I see a resident or business washing down a surface and discharging to a storm drain?
- Will residents be fined for noncompliance?
- What is the MEP standard for storm water?
- What is an illicit discharge?
- Is a property owner responsible when a contractor discharges illegally?
- Do MS4 Permits authorize the discharge of reclaimed water to surface waters?
- What is the purpose of storm water monitoring?
- Where can I see results of water quality monitoring?
- Must the City or County inspect the management measures for controlling pollutants in storm water runoff at my industrial facility if the State of California is already inspecting the site?
- What will a City or County inspection of my facility entail?
The San Diego Water Board issues an MS4 permit in order to establish the conditions under which pollutants can be discharged from the storm drain system to local streams, coastal lagoons, and the Ocean. The MS4 permit implements requirements of the Clean Water Act and Federal NPDES stormwater regulations. Since 1990, permits have been issued to municipalities based on their county location and watershed characteristics.
Federal regulations require that municipalities obtain this permit (known as a National Pollutant Discharge Elimination System, or NPDES, permit) and renew it every 5 years. Under this permit each municipality must develop a storm water management program designed to control the discharge of pollutants into and from the MS4 (or from being dumped directly into the MS4). The purpose is to protect local waterbodies since storm drains typically dump their water into streams, bays, and/or the ocean without being treated. The State of California has the authority to issue this federal permit.
An MS4 includes the conveyance or system of conveyances designed or used for collecting or conveying storm water that is not a combined sewer or part of a publicly owned treatment works. It includes roads with drainage systems, municipal streets, catch basins, curbs, gutters, ditches, man-made channels, or storm drains. These drainage systems typically dump their water (and any associated pollutants) directly into streams, bays, and/or the ocean.
Storm water management programs must include measures to:
- Identify major outfalls and pollutant loadings;
- Detect and eliminate all non-storm water discharges to the system, except as specifically exempted;
- Prevent and reduce pollutants in runoff from industrial, commercial, and residential areas through the implementation of BMPs (Best Management Practices);
- Control storm water discharges from new development and redevelopment;
- Inspect industrial, commercial, and construction activities;
- Provide pertinent education and promote public reporting of pollution;
- Monitor discharges and impacts on receiving waters.
The MS4 permit prohibits most discharges into and from MS4s that cause or threaten to cause water pollution. Storm water discharges of pollutants must be reduced to the maximum extent practicable (MEP), and most non-storm water discharges are not allowed. A limited number of non-storm water (i.e., dry-weather) discharges were explicitly exempted by the federal regulations. Activities that generate pollutants must be performed in a way so as to keep the runoff from entering the storm drains.
Yes, as long as you effectively stop runoff of car wash water from your driveway into the storm drain. Car wash water from car washing typically contains pollutants (e.g., detergents, oil and other automobile fluids, and metals), and discharges from car washing activities that enter the storm drain can cause a condition of pollution in local waters. Best Management Practices (BMPs) should be implemented in a way to keep the car wash water runoff from entering the storm drain. A great way to prevent pollutants from entering the storm drain at your house is to take your car to a car wash facility. Carwash water at a car wash facility is recycled to remove pollutants and protect the environment. Discharges from other types of car washing are not exempted from the regulations. Other types of car washing (i.e. car washing businesses, charity car washing events, fleet washing of company vehicles, etc.) , should also be conducted so that the wash water does not enter the storm drain.
Yes, as long as you don't over irrigate causing runoff from your lawn to discharge into the storm drain at the edge of your property. Landscape over irrigation runoff contains pollutants that could pose a threat to water quality (e.g., pesticides, herbicides, excess fertilizer, and pet waste). Runoff from putting too much water on your lawn can mobilize excess fertilizer, pesticides, and herbicides moving them into the storm drain, creeks, rivers, bays and eventually the ocean impairing the health of local waters. Your City may have a residential Best Management Practice (BMP) Program that provides information on ways to eliminate over-irrigation and the discharge of pollutants in over-irrigation runoff to ensure the proper application of irrigation water. This BMP Program may also provide information on the proper application of landscape and garden products, such as fertilizers and pesticides.
Municipalities are required to implement practices to control the amount of pesticides, herbicides, and fertilizers that run off municipal facilities. In addition, because landscape runoff may contain pollutants (e.g., pesticides, herbicides, excess fertilizer, and pet waste), including ones toxic to wildlife, the municipalities have an obligation to educate residents in order to prevent and reduce water pollution from these sources.
Wash water from patio or driveway washing in commercial and residential areas are considered illicit discharges to the MS4 and are required by federal regulations to be effectively prohibited by the City or County with authority to control such discharges. Wash water from patios, driveways, eating and drinking areas, parking lots, and other types of impervious surfaces are not exempted from the federal regulations. Automobile fluids, metals from automobiles, landscaping materials, pet waste, and trash washed off, patios or driveways are examples of pollutants that threaten the quality of receiving waters. Each city and county are required by federal regulations to implement and enforce an ordinance, orders or similar means to prevent illicit discharges to the MS4. Therefore, wash water from driveways, parking lots, patios, and other surfaces must not be allowed to enter the storm drains. If you must wash down your driveway or parking lot, you must implement best management practices to prevent the wash water from entering a storm drain (i.e., use a mop and bucket to eliminate runoff, block off the storm drain inlet and vacuum up wash water, direct the discharge onto your lawn for infiltration, etc.).
If you see someone discharging wash water, or any other discharge containing pollutants, to a storm drain, you should notify the city or county in which you are located. All municipalities should have reporting numbers listed in the phone book and/or on the Internet.
It is up to each municipality to decide how to enforce its prohibitions on illicit discharges. We expect enforcement will be based on certain factors, such as proportional threat created by the discharge, prior enforcement history, and others. Several types of enforcement options, including effective education, are available to the municipalities.
Each municipality's storm water management program must be designed to reduce pollutants discharged from storm water to the Maximum Extent Practicable (MEP). The federal regulations do not define MEP, but in general, to achieve the MEP standard, municipalities must employ whatever Best Management Practices (BMPs) are likely to be effective and are not cost-prohibitive. Through development of its management program, each municipality proposes a BMP-based program to achieve MEP. It is the responsibility of the municipality to ensure that the BMPs are implemented, and it is the responsibility of the San Diego Water Board to determine when MEP has been met.
Illicit discharges include both storm water with pollutants that have not been reduced to the Maximum Extent Practicable (MEP) and most non-storm water flows. These discharges are "illicit" because Municipal Separate Storm sewer systems (MS4s) are not designed to process, treat, or remove pollutants from either storm water or non-storm water flows. The result is untreated discharges that contribute high levels of pollutants, including heavy metals, toxics, oil and grease, solvents, nutrients, sediments, viruses, and bacteria into receiving waterbodies. Programs that reduce illicit discharges to separate storm sewers can improve water quality.
The MS4 permits require that municipalities develop and enforce ordinances addressing prohibited discharges. Thus, responsibility is determined by local government regulations. Depending on the circumstances and your local code or ordinance, the contractor and/or the property owner may be responsible.
The MS4 Permit do not authorize direct discharges of reclaimed water to surface waters. However, the Regional MS4 Permit issued by the San Diego Water Board does not require municipalities to differentiate between potable irrigation water and reclaimed irrigation water. The use and distribution of reclaimed irrigation water, is regulated by a separate permit, which is issued to the reclaimed water purveyor. Purveyors must require users to implement Best Management Practices (BMPs) to reduce or eliminate runoff.
The federal NPDES regulations require all MS4 permits to include a monitoring program to collect data representative of runoff and receiving waters in permitted areas. The main purposes of storm water monitoring include:
- Providing a means for evaluating the environmental risks of storm water discharges by identifying types and amounts of pollutants present;
- Determining the relative potential for storm water discharges to contribute to water quality impacts;
- Identifying potential sources of pollutants;
- Eliminating or controlling identified sources through permit conditions; and
- Assessing the effectiveness of permit conditions and storm water management programs.
Data is collected throughout the year by the municipalities and reported annually to the San Diego Water Board. The annual reports are available for review at the San Diego Water Board office. Municipalities may make data available via their web sites or upon request as it is analyzed. Please contact your local municipality for recent data.
The San Diego Water Board does not require the City or County to inspect a facility during a year that the facility has already been inspected by the San Diego Water Board staff. However this does not preclude the City or County from inspecting the site, especially if the facility's storm water management measures have been lacking in the past.
The MS4 Permit require municipalities to ensure, through inspection, the implementation of minimum BMPs at all industrial and commercial facilities within their jurisdiction. You can expect City or County storm water inspectors to: 1) check for coverage under the Industrial General Storm Water Permit (IGP); 2) assess compliance with local ordinances related to storm water runoff, including the implementation and maintenance of designated minimum BMPs; 3) make visual observations for non-storm water discharges, potential illicit connections, and potential discharges of pollutants in storm water runoff; and 4) provide education and outreach regarding storm water pollution prevention. Inspections will vary depending on local ordinances and permits.