Surface Water Management Fee Discounts and Cost-Sharing Program

To promote the reduction or mitigation of impervious surface -- the main contributor to surface water runoff and its adverse effects (i.e. water quality degradation, erosion, flooding and sedimentation), several discounts, credits, and cost-share opportunities are available to owners of developed parcels. These are briefly described below and explained in detail in a procedures document titled, SWM Fee Protocols (PDF, 685 kb). To learn more about these discounts, credits, and cost-share opportunities, contact a surface water, customer service representative by calling 206-296-6519 or refer to the SWM Fee Protocols.

Runoff Mitigation Discounts

Your parcel may qualify for one of the following three runoff mitigation discounts.To learn more about these or to request this type of discount, contact the Stormwater Services Section at 206-296-1900.

Stormwater Facility Discount

If you operate or bring into operation one or more stormwater flow control or water quality treatment facilities approved to be functioning properly within County standards, you may be eligible to reduce your fee by being placed in one rate category lower. Facility inspection occurs annually by engineers. Residential parcels meeting this condition will receive a discount equal to half the residential fee, or $55.50. Both residential and commercial properties are eligible. This discount may not be combined with other runoff mitigation discounts.

Sixty-Five-Ten Discount

Your fee assessment may qualify for a discount if your property is at least sixty-five percent forested, has no more than ten percent effective impervious area and Best Management Practices for dispersing and infiltrating your runoff are being met. In some cases, technical information such as a topographic survey may be required. Other conditions may apply and at least one site visit will be required for approval, but qualification for this discount would lower your assessment by one-rate category. Residential parcels meeting this condition will receive a discount equal to half the residential fee, or $55.50. Both residential and commercial properties are eligible. This discount may not be combined with other runoff mitigation discounts.

Pervious Surface Absorption Discount

Your fee assessment may qualify for up to twenty five percent discount if you implement county-approved flow control Best Management Practices and at least ten percent of your impervious surface is served by these practices. In some cases, technical information such as a soils report may be required, and you are not eligible for this discount if you already receive another runoff mitigation discount. Only commercial properties are eligible.

Impervious Surface Cost Share and Credit Program

As an incentive to reduce impervious surface, the county is making funds available for sharing the costs of converting impervious surface to (1) native-vegetated landscape, (2) compost-amended lawn or (3) grassed, modular-grid pavement. To qualify, a plot plan, technical information and description must be submitted to county engineers who will work with you to develop your plan. Fifty percent of costs up to $20,000 will be reimbursed after the job is complete and inspected. Reducing your impervious surface could potentially place you into a lower rate category, reducing your fee. Only commercial properties are eligible. To learn more about this program, contact the Stormwater Services Section at 206-296-1900 or refer to the SWM Fee Protocols

Open Space Discount

If your property were to be classified as "open space", "agriculture" or "timber" and enrolled in the Current Use Taxation Program, or if your development rights were to be sold, you could be eligible for a fee reduction. Both residential and commercial properties are eligible.

Low-Income Senior Exemption

If you are a low-income, senior citizen that lives on property you own, you may be exempt from the surface water fee. The Office of the King County Assessor determines qualifications for exemption and applications can be made by phoning 206-296-3920. Only residential properties are eligible.

Administrative Appeals Process

If you feel your assessment or impervious surface measurements are incorrect or that your discount has not been appropriately applied, please speak to one of our customer service representatives so that we can review your assessment promptly.

In some cases, you may already qualify for a discount, in others fee reductions may not be granted until next year. The cost-sharing program is available on a first come, first serve basis until annual appropriations are expended. Please contact a surface water, customer service representative at 206-296-6519 for more information about any of these options. We pledge to let you know if you will qualify within 30 days of your application unless we find that additional information is needed to determine your eligibility.

Visit the Common Questions and Answers page for answers to other surface water management-related questions. For more detailed, technical information about SWM fee measurement, discount requirements, how to apply for a cost-sharing grant or about pervious surface credits, refer to SWM Fee Protocols document (PDF, 685 kb).