Issaquah, WA Landscaping Rules: Water Restrictions (2026)

Section 18.606.060 of the Issaquah Land Use Code, Irrigation and water standards, governs how landscape irrigation is built and run. It prints no odd-even or day-of-week watering schedule. Paragraph (A) states the purpose, protecting environmental functions while promoting efficient use of water, and requires a permanent, efficient irrigation system in all landscapes unless exempted under the section.

For projects that require a site development permit under Chapter 18.208 IMC, paragraph (B) requires at least three of six techniques: subsurface or drip irrigation; sprinkler head selection and spacing designed to minimize overspray; plants with similar water needs, soil moisture sensors, and separate zones for turf and shrub hydrozones; design of a minimum of 25 percent of landscaped areas for long-term irrigation from harvested rainwater such as rain barrels or rain gardens; recycled water or greywater; or other technology that reduces water use equally or more, as the applicant demonstrates. Paragraph (C) requires every system to include a rain and soil moisture sensor designed to shut off or override watering during rainfall events.

Paragraph (E) requires designs that avoid runoff, low-head drainage, and overspray onto adjacent property, nonirrigated areas, or impervious surfaces, using proper schedules with repeat cycles and matched precipitation and infiltration rates. Paragraph (H) requires low-volume subsurface irrigation with a distribution uniformity of not less than 0.90 in right-of-way medians, curb strips, parking lots, and other landscape strips under five feet wide, and for turf-grass exceeding a 3:1 slope. Paragraph (I) requires winterization through manual drains at all low points or a method to blow out pipes with pressurized air, and paragraph (J) requires periodic maintenance and inspection to adjust scheduling.

Deviations approved per IMC 18.606.190 are listed in paragraph (D): letting lawns brown during the summer (June through September), approved xeriscape plantings, drought-tolerant or established indigenous plants, and landscaping tied to low-impact development stormwater systems. Public irrigation systems must use a master control valve connected to a flow sensor and irrigation controller (G).