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Q What is surface water management?

Surface water management (SWM) combines landowner assistance, maintenance and construction projects, stewardship, regulatory requirements, and restoration programs to protect public health and safety, and the waters and lands in unincorporated King County. We use these tools to identify, fix, prevent, and lessen the impact of stormwater runoff and other water quality problems such as erosion, pollution, habitat degradation, and changes in water flow and temperature.

Q Why has my SWM fee increased?

The Water and Land Resources Division has programs to address surface water runoff and water quality challenges that come from over 125 years of development and alterations to natural systems. We are also required to meet state and federal laws and regulations. To do this, the increased SWM fees support:

  • Improving the condition of stormwater flow structures under county roads that carry runoff;
  • Managing stormwater assets, maintaining and replacing aging infrastructure. By keeping infrastructure functioning properly through inspections, maintenance, repair, and replacement of aging facilities such as pipes, storage ponds, culverts, and catchbasins, we can avoid the potential high costs and disturbances of emergency repairs;
  • Mapping the stormwater conveyance system in the county right-of-way to meet requirements of the National Pollutant Discharge Elimination System permit;
  • Increasing habitat restoration projects to improve water quality and help recover salmon populations;
  • Supporting productivity of local farmers through the agricultural drainage assistance program and the Farm, Fish, and Flood effort;
  • Monitoring effectiveness of fish and habitat restoration projects to assess their usefulness;
  • Addressing chronic drainage flooding issues through natural drainage system projects;
  • Implementing an improved infrastructure software system that will tie together existing programs to be more effective and efficient;
  • Developing and implementing a beaver management strategy to address and monitor the growth of beaver populations and the resulting challenges to property management;
  • Developing a new water quality grant program to assist residents and communities in making water quality improvements;
  • Creating a discount program for low-income property owners to mitigate impacts of a SWM rate increase;
  • Coordinating and helping create a continuous tree canopy along the Lower Green River to maximize shade and help improve water quality.

Q When did this program fee start? 

King County's SWM program and fee began in 1987 and is applied to parcel owners in unincorporated King County. Almost every city in King County has its own SWM program and assesses a fee to pay for it. Surface water management is a requirement of the federal Clean Water Act. Under that act, many counties and cities in the state and many businesses have a National Pollutant Discharge Elimination permit and are required to comply and protect water quality. As a result, many governments have SWM programs to address these requirements and charge a SWM fee to fund their programs.

Q Do new housing and commercial developments pay this fee?

Yes, landowners for every developed parcel – residential or non-residential properties that have impervious surfaces – in unincorporated King County pay this fee unless they are exempt by King County Code or state law.

Q How is the money spent? 

There is a short list of projects and responsibilities at Surface water management fee page.  

Q Does the money pay for salmon or fish?

Fee revenue is used to build projects that improve drainage, water quality, and stream bank stability that also improve fish habitat. A small amount pays for King County's part in salmon recovery efforts. To respond to the Endangered Species Act, there are four watershed areas in King County where groups of scientists, elected officials, and representatives from cities and community groups work together to protect salmon habitats. Improvements to fish habitat generally improve water quality too.

Q How does the fee help farmers?

Part of the fee pays for programs that help farmers and the agricultural community through:

  • The Agricultural Drainage Assistance Program helping farmers dredge waterways in their fields.
  • The Livestock Management Cost-Sharing Program shares the cost of putting up fences that prevents animal waste from polluting waterways.

Q How do I know this money will be spent on surface water related services? 

By law, SWM fees funds must be, and can only be, spent on surface water management-related projects and services. Both state statutes and King County Code limit how these fees can be spent. Washington State and/or the King County auditors routinely audit the program to make sure that fee revenues are being spent according to the law and good accounting practices are being maintained. The annual county budget process also requires the Water and Land Resources Division to report to the King County Council and the Executive about how fee dollars are spent.

Q What happens if I don't pay this fee?

This fee is billed with property taxes. If you don't pay the fee or only pay your property tax payment -- excluding the surface water fee -- King County's Office of Finance will not accept your payment, and your check will be mailed back to you. Both taxes and the fees will become delinquent and subject to interest and penalties.

Q When is this fee due?

This fee is due in two installments on April 30 and October 31, the same as property taxes.

Q I am a commercial property owner, how is my fee charged?

First, we measure the impervious surface on your parcel. The percent of impervious surface on your parcel is calculated using the total parcel acreage. The percentage of impervious surface places your parcel in a rate class; see the Fee Rate Table. Your parcel’s total acreage multiplied by the per-acre charge of that particular rate is your SWM fee: 

Annual SWM rates for 2019 and 2020
Rate class Description % Imperv. surface Fee
1 Residential NA $289.00 per parcel
2 Very light ≤ 10% $289.00 per parcel
3 Light > 10.1 ≤ 20% $803.51 per acre
4 Moderate > 20.1 ≤ 45% $1,504.04 per acre
5 Moderately heavy > 45.1 ≤ 65% $2,566.60 per acre
6 Heavy > 65.1 ≤ 85% $3,575.37 per acre
7 Very heavy > 85.1 ≤ 100% $4,399.10 per acre

Q I don't think my fee is correct. What can I do?

If you think your property is not correctly classified as residential or non-residential, that the calculation of impervious area is incorrect on a non-residential parcel, that a SWM fee discount is either not applied or is incorrectly applied, or for other questions, call Water and Land Resources Division customer services at 206-477-4800.

Q Why is gravel impervious?

Packed gravel prevents or blocks water seeping into the soil as natural soil conditions would function. Scientific studies show that once gravel is compacted, for example, from cars or heavy equipment, the gravel acts like paved surfaces and surface water runs off it in greater quantities than compared to natural soil conditions.

Q My property is enrolled in the Open Space Program or classified as state forest land. How is my fee being assessed?

If you are enrolled in the Open Space Program, you are eligible for a discount. Instead of multiplying your rate by the total acreage of your parcel, we multiply your rate by only the number of impervious acres. Parcels classified as forest land by the state are exempt from the SWM fee. To verify whether you are being billed correctly, call Water and Land Resources Division customer services at 206-477-4800.

Q Is this a fee, or a tax -- what's the difference?

By state statute and county code, the SWM fee is not a tax. The courts both in King and Clark counties have upheld this determination. Generally speaking, taxes are based on levels of income or some kind of valuation. Fees are charged based on a contribution to a problem and are earmarked funds that can be spent only on specific activities. The SWM fee is directly linked to the problems associated with runoff from impervious surfaces, and it pays for specific services and programs to identify, fix, or prevent those problems.

Q What discounts are available for residential property owners?

  • Low-income senior citizen discount -- full exemption. Call the Assessor's Office at 206-296-3920 to qualify.
  • Flow control/water quality (drainage) facility discount.

For more information, and discounts for non-residential parcels, visit our SWM fee discounts web page.

Q I am a senior citizen, why do I have to pay this fee?

If you qualify as a low-income senior citizen for property tax relief, you will be exempt from the SWM fee for the parcel that has your personal residence on it. The Assessor's Office processes property tax relief requests. To apply, call the Assessor's Office at 206-296-3920.

Q What discounts are available for non-residential property owners?

Please refer to our SWM fee discounts web page.

Q I have a flow control or water quality facility on my site, can I qualify for more than one discount or for the grant program?

Possibly, please see the SWM fee discounts web page.

Q Can I remove part of my parking lot to reduce my fee?

This may be possible. Call Stormwater Services Section customer service at 206-477-4811 to discuss what could work for your site.

Q Where Can I Get More Information?

For questions about your fee, call the Water and Land Resources customer services at 206-477-4800. To speak to a stormwater engineer about your parcel, call Stormwater Services Section customer service at 206-477-4811.

Surface water management fee