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Pima County, AZ Environmental Rules: Grading & Drainage (2026)

Heavy Restrictions

Verified 1 month ago|Source: Pima County RFCD Drainage Design Manual →

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Key Facts

Permit Authority: Development Services
Drainage Review: RFCD Drainage Design Manual
Wash Setbacks: 25-100 ft by classification
Steep Slope Trigger: 15 percent grade
Retention

City-specific rules exist: Marana, Sahuarita, Oro Valley, and Tucson have their own grading & drainage rules that differ from Pima County's county-level regulations. If you live in one of those cities, check the city-specific page instead.

Summary

Pima County requires grading permits for land disturbance in unincorporated areas and enforces strict drainage standards through the Regional Flood Control District. All new construction must demonstrate that post-development drainage does not increase runoff to adjacent properties. Washes and arroyos have mandatory setback buffers.

Full Breakdown

Pima County Development Services issues grading permits under the county grading ordinance and floodplain management code (Title 18). The Regional Flood Control District reviews drainage plans to ensure compliance with the Drainage Design Manual. Key requirements include maintaining predevelopment drainage patterns, retaining the first inch of stormwater on-site, and maintaining setbacks from regulatory floodways and erosion hazard zones. Wash setbacks range from 25 to 100 feet depending on wash classification (minor, major, or critical). Cut and fill operations exceeding specific thresholds require engineered plans stamped by an Arizona-registered professional engineer. The county also regulates watercourse modifications under the floodplain use permit process. Grading on slopes exceeding 15 percent triggers additional geotechnical review. Desert terrain grading must preserve natural drainage patterns and minimize scarring visible from public roadways.

Violations & Fines

Grading without a permit results in stop-work orders and penalties up to $300 per day. Altering drainage patterns that cause flooding to adjacent properties may result in enforcement action, restoration orders, and civil liability. Building within wash setbacks without a floodplain use permit is a code violation subject to structure removal.

Frequently Asked Questions

Do I need a grading permit in unincorporated Pima County?

Yes. Any significant land disturbance requires a grading permit from Pima County Development Services. Projects near washes or in floodplains also need RFCD drainage review and possibly a floodplain use permit.

What are the wash setback requirements in Pima County?

Setbacks from washes range from 25 to 100 feet depending on the wash classification. Building within these setbacks requires a floodplain use permit and may be prohibited entirely in critical erosion hazard zones.

Can I redirect drainage on my property in Pima County?

You may not redirect drainage in a way that increases runoff to neighboring properties. Post-development drainage must match or improve predevelopment patterns, and the first inch of rainfall must be retained on-site.

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Pima County, AZ Environmental Rules: Grading & Drainage (2026)

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