Yakima County, WA Environmental Rules: Stormwater Management (2026)
Key Facts
- Plan trigger
- Disturbing one acre or more
- Also triggers at
- More than 4 new lots created
- Administered by
- Yakima County Public Services Director
- Civil infraction
- Class 1, $250 maximum penalty
- Willful facility damage
- Up to $1,000 fine, 90 days jail
- Appeal path
- Public Services Director, per YCC 16B.09
- State authority
- RCW 36.89, RCW 90.48, Clean Water Act
Summary
Any land-disturbing project of one acre or more in unincorporated Yakima County, or a smaller phase of a larger development, needs Public Services Director approval of a stormwater plan under YCC § 12.10.210 before construction starts. The chapter also runs the county's MS4 permit program, SWPPPs, and Class 1 civil infractions for skipping the process.
The approval of applications for land development or redevelopment projects (projects) that are submitted pursuant to Yakima County Codes 12, 13, 19, 16C, and 16D that meet the following criteria shall be subject to the approval of a stormwater plan by the Public Services Director: (a) Projects that disturb a land area greater than or equal to one acre. (b) Projects that disturb a land area less than one acre when the project is part of a larger common or combined plan of development where the combined projects disturb a land area greater than one acre... (c) Projects where the division of land creates more than 4 lots... (g) Projects that discharge stormwater to the MS4. (h) Projects with high potential for sediment transport.
Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: rev 4871853; v6 updated 2026-04-21; through 04-21-2026).
Full Breakdown
Yakima County Code Chapter 12.10, the Stormwater and Drainage Authority, exists to provide for the protection of the citizens of Yakima County from stormwater and drainage damage through planning and the regulation of site drainage and discharges to stormwater control facilities and waters of the state, per § 12.10.100. The county adopted the chapter under RCW 36.89 (Stormwater Control), RCW 90.48 (Water Pollution Control Law), and the federal Clean Water Act, and named the Public Services Director as the official who administers it (§ 12.10.110).
A stormwater plan approved by the director is required before county permits under Titles 12, 13, 19, 16C or 16D can be issued for any project that disturbs one acre or more, that is part of a larger phased development exceeding one acre in total, that divides land into more than four lots, that discharges to the county's MS4, or that a SEPA review, sediment-transport risk, or the director's own determination flags for erosion or water-quality concerns (§ 12.10.210(1)). Projects inside the Stormwater Utility service area that trip these thresholds must also submit a Stormwater Pollution Prevention Plan for the director's completeness review (§ 12.10.220). The chapter exempts emergency work needed to protect life or property, forest practices regulated under Title 222 WAC, ordinary agricultural cultivation (though new impervious surfaces on a farm are not exempt), oil and gas field activity, and routine road-maintenance work like pothole patching or crack sealing (§ 12.10.210(2)).
Builders who move dirt without an approved plan, or who fail to retain runoff on-site to the chapter's design criteria, are in violation under § 12.10.440(3)(b)-(c). Violations are Class 1 civil infractions with a $250 maximum penalty per offense, each week of an uncorrected violation counted separately, and stormwater or grading decisions can be appealed to the Public Services Director under YCC Chapter 16B.09 (§ 12.10.470).
Violations & Fines
Skipping a required stormwater plan, building without the director's approval, or failing to retain runoff on-site under the approved design are each violations of Chapter 12.10 (§ 12.10.440(3)). Most are Class 1 civil infractions capped at $250 per offense under § 12.10.450(22), but willfully damaging a county drainage or stormwater facility is instead a misdemeanor punishable by up to $1,000 and 90 days in jail under § 12.10.440(1)(a).
Frequently Asked Questions
Does my unincorporated Yakima County project need a stormwater plan?
Are farms and forestry exempt from the stormwater rules?
What's the penalty for building without an approved stormwater plan?
Can I appeal a stormwater plan denial?
Sources & Official References
Other rules in Yakima County
Compare Yakima County to another location·View the Washington environmental rules overview
See something wrong?
Help us keep this page accurate. If you notice an error or outdated information, let us know.