Thurston County, WA Water Use Rules: Recycled Water Rules (2026)

Thurston County Code Section 24.10.190 governs recycled (reclaimed) water use inside the county's critical aquifer recharge areas (CARAs), the zones mapped under Chapter 24.10 where groundwater is especially vulnerable to contamination because it recharges the aquifers used for drinking water. Subsection A permits irrigation with Class A reclaimed water at agronomic rates in every CARA in the county, subject to the general CARA development standards at TCC 24.10.030. Class A is the top tier of Washington's reclaimed-water quality classification, defined in the county code by reference to RCW 90.46.010 and the state Department of Ecology's reclaimed water standards; agronomic rates means application at the level plants can actually use, not disposal-scale spreading.

Subsection B addresses the other end of the practice: infiltrating reclaimed water into the land's surface at rates above what plants take up. The code does not set numeric limits or a permit process for that activity yet. Instead it states plainly that critical area regulations for higher-rate infiltration will be proposed once Thurston County has more data from the Regional Groundwater Recharge Scientific Study, in keeping with the state Growth Management Act, Chapter 36.70A RCW. Anyone proposing a wastewater treatment or reuse facility, or a satellite recycling plant, that does NOT involve injection or infiltration of reclaimed water is instead routed to TCC 24.10.100, which classifies those facilities by CARA vulnerability category (prohibited in the most vulnerable zones, permitted subject to conditions in others).

The chapter was adopted by Ordinance No. 14773, § 3 (Attachment B), effective July 24, 2012, and administered by Thurston County Community Planning & Economic Development as the approval authority for CARA review.