Spokane County, WA Environmental Rules: Stormwater Management (2026)
Key Facts
- 2026 ERU rate
- $48.00 per year
- 2029 ERU rate (held after)
- $84.00 per year
- 1 ERU
- 3,160 sq ft impervious surface
- Billing due dates
- April 30 and October 31
- Delinquent interest
- 12% per year (RCW 36.89.092)
- System development charge
- up to $2,000 per ERU
Summary
Spokane County charges every developed parcel in unincorporated areas an annual stormwater service fee based on impervious surface area. Residential lots pay a flat equivalent residential unit (ERU) rate, currently $48.00 and rising to $84.00 by 2029, billed through the county treasurer.
(a)Service charges imposed by this chapter shall be based on the relative contribution of increased stormwater runoff from a given parcel to the stormwater management system... (b)(1)Residential parcels as defined in this chapter shall receive a flat rate service charge based on the average area of impervious characteristics of residential parcels in Spokane County. This shall equal the rate for one equivalent residential unit (ERU). The flat rate per year applied to residential parcels shall vary by drainage service area as follows: Annual Rate per ERU 2026 2027 2028 2029 Stormwater service area $48.00 $60.00 $72.00 $84.00 Rates will remain at the 2029 levels until amended
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 63).
Full Breakdown
70, the Spokane County stormwater utility charges owners of record for every developed parcel in the unincorporated stormwater service area, funding a countywide network of stormwater runoff facilities. The charge is based on impervious surface, defined as roofs, driveways, patios, parking areas, gravel roads, and other surfaces that block natural infiltration. One equivalent residential unit (ERU) equals 3,160 square feet of impervious surface, the countywide average for a single-family lot. 00 in 2029, after which rates hold at the 2029 level until the board of county commissioners amends them by resolution.
0 for grassy or undeveloped surfaces. 055 to help finance regional stormwater capital projects. Bills are split into two installments through the county treasurer, due April 30 and October 31 each year.
Violations & Fines
A parcel owner who misses a payment becomes delinquent after October 31, and unpaid charges accrue interest at 12 percent per year under RCW 36.89.092. The county attaches a lien against the property for delinquent charges that is superior to nearly all other liens except general taxes and special assessments, and after 60 days the county may sue in superior court to foreclose the lien, recovering attorney's fees in addition to statutory costs. A billing dispute must first go to the stormwater utility director as a rate-adjustment application; the director's denial can be appealed to a county hearing examiner within 30 days, and the hearing examiner's ruling can be further appealed to the board of county commissioners, then to superior court by writ of certiorari.
Frequently Asked Questions
How much is the Spokane County stormwater fee for a house?
When is the Spokane County stormwater bill due?
What happens if I do not pay my stormwater charge?
Can I dispute my Spokane County stormwater bill?
Sources & Official References
Other rules in Spokane County
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