Frequently Asked Questions
King County Phase I National Pollution Discharge Elimination System (NPDES) Municipal Stormwater Permit

As part of its ongoing commitment to protect public health and improve environmental conditions in our streams, rivers, lakes and Puget Sound, King County has developed a stormwater management program to meet requirements of the Washington State Department of Ecology (Ecology) Municipal NPDES stormwater permit.

The program is reviewed and updated annually, providing the public with an ongoing opportunity to review and comment on the program’s development and implementation.

Stormwater is one of the most significant sources of pollution of our nation’s waters. Ecology has identified stormwater as the most significant contributor to reduced water quality in Puget Sound, which is targeted for clean up by the Puget Sound Partnership.
As part of the Puget Sound clean-up strategy, Ecology used the authority delegated to it by the Environmental Protection Agency (EPA) to implement a National Pollutant Discharge Elimination System permitting program and issued restrictive stormwater permits to municipalities.

What is stormwater?
Stormwater is runoff from rain or melting snow that falls on streets, parking lots, sports fields, rooftops or other developed land and flows across the ground then enters nearby lakes, rivers and streams, eventually reaching Puget Sound. In a natural setting, most of this water would seep into the ground or evaporate back into the air through the plants and trees. However, when the vegetation is removed and the ground is cleared, compacted, or covered with a hard or impervious surface, more stormwater results. Stormwater typically picks up various pollutants as it flows across the buildings, roads, driveways and developed landscape, including pesticides and fertilizers, bacteria and viruses from pet waste, metals and oil from vehicles, trash and other chemicals.

What happens to stormwater in King County?
No matter the route it takes, stormwater eventually reaches Puget Sound. Stormwater flows downhill through natural pathways, such as streams and rivers, and manmade structures like sidewalks, driveways, roads, ditches and pipes. Historically, municipalities have engineered elaborate systems of pipes, ditches, and other structures to remove stormwater from developed property to prevent flooding. These systems typically involve little to no treatment of the stormwater as they are designed to efficiently transport it to a waterbody like a stream, river or directly to Puget Sound.

Is stormwater treated?
Unlike wastewater, stormwater is not sent to high-tech treatment plants before being discharged to Puget Sound. Stormwater generated from development that was built prior to 1990 is not treated. Approximately 70 percent of the development within unincorporated King County was completed before 1990 and therefore the stormwater from these areas is discharged into the local waters without treatment.

Sites developed after 1990 have had to meet new stormwater regulations on development .which have  focused on reducing contaminant loads and reducing the volumes of stormwater flowing off of sites during and after development. Options to achieve these goals include setting aside undeveloped parts of the site, treating stormwater with onsite low-tech facilities such as vegetated swales and “wet” ponds, or construction of regional stormwater facilities.

Is stormwater a threat to the environment?
Stormwater runoff has been identified as the number-one cause of pollution in Puget Sound, and the rate of stormwater runoff has increased as land was developed and converted from forests and fields into properties with impervious surfaces. The increased runoff picks up more pollutants and flows at faster rates into streams and Puget Sound. Increased pollutant levels threaten both human health and safety and the survival of the fish and wildlife that live in streams and in the Sound. Increased rates of flow destroy the habitat functions of streams and disrupt the Puget Sound ecosystem’s food web. For more information on the regional effort to restore and protect Puget Sound, visit the Puget Sound Partnership website (external link).

What is an NPDES Municipal Stormwater permit?
Congress established the National Pollution Discharge Elimination System (NPDES) in 1972 as part of the Clean Water Act. The NPDES Stormwater Program is a two-phased national program for addressing stormwater discharges. The municipal NPDES program issues permits to municipalities, including cities, counties, ports and other governmental entities and requires them to undertake efforts to reduce water pollution from stormwater by implementing steps referred to as best management practices (BMPs), that can refer to a wide variety of pollution prevention systems or efforts. These can range from physical structures such as treatment ponds, to non-structural things such as education programs designed to teach people to reduce pollution. For more information please visit the U.S. Environmental Protection Agency’s (EPA) NPDES Permit Program website (external link).

What will the permit do to clean up Puget Sound?
The municipal stormwater permits are intended to reduce the volume of stormwater-borne pollutants entering natural waterbodies, including Puget Sound. If they achieve their goal, the reduction of pollutants flowing into Puget Sound from stormwater could reduce overall pollution in the Sound, particularly for pollutants such as petroleum products, metals and bacteria that are commonly associated with stormwater. It is important for all of King County’s citizens to realize the role they play in protecting local water quality, and King County has supported educational efforts like the Puget Sound Starts Here (external link) program to help share this message.

Why did the Washington State Department of Ecology issue this permit?
The Clean Water Act allows the EPA to delegate NPDES permitting to individual states that meet specified requirements. The State of Washington has met those requirements and is authorized to implement the NPDES permit program in the state through Ecology.

Is this King County’s first permit?
King County was covered under Washington’s first municipal stormwater permit, which was issued in 1995. The current permit became effective in February 2007. King County is also covered under many other NPDES permits, including individual permits for its wastewater discharges and the Cedar Hills Regional Landfill, the industrial Sand and Gravel permit for road maintenance shops in old gravel pits, and the construction stormwater permit for construction sites of one acre and larger in size.

What other municipalities are regulated under NPDES municipal permits?
The NPDES permits were issued in two phases. Under Phase I, only municipalities with populations of 100,000 or larger based on the 1990 census were covered under the municipal stormwater permit. In Washington, this included Clark, King, Pierce, and Snohomish counties, the cities of Seattle and Tacoma, and the Washington State Department of Transportation. In 2007, new Phase II permits extended municipal stormwater permit coverage to include most municipalities in the Puget Sound Basin. To see the extent of Phase II coverage in King County, vist:

• King County Stormwater Permit Areas Map (PDF, external link)
• Seattle Urban Area/King County Permit Areas Map (PDF, external link)

For a list of permittees, see Who's Covered Under the Municipal Stormwater Permits (external link) by Dept. of Ecology.

How will my bills change?
The Surface Water Management fee is a significant source of funds for King County’s compliance with its municipal stormwater permit. Permit compliance has required substantial increases in funding in some program areas, and King County has to balance the fees collected with the levels of services provided. King County's surface water management fee is based on the average amount of impervious surface on residential properties and the overall amount and parcel size of commercial properties.

What are the repercussions of non-compliance?
The Washington State Department of Ecology and third parties, including citizens and environmental groups, can sue municipalities for not complying with permits. Penalties include fines of up to $32,500 per violation, per day.

Will the permit affect development proposals?
Permit requirements will result in minor modifications to the existing thresholds for drainage review of development projects, and could also result in drainage or erosion and sedimentation control inspections for projects that might not otherwise receive them.

Will the permit prevent flooding?
The permit is not intended to address flooding. While much of the stormwater conveyance system is designed to prevent flooding, this permit is focused on efforts to improve water quality and reduce stormwater runoff.  King County provides extensive flood prevention services. For more information on this work visit King County’s flooding services and information website.

For questions about the 2011 update of the King County Stormwater Program, please contact Giles Pettifor, Project/Program Manager, Stormwater Services Section.