Oro Valley, AZ Environmental Rules: Grading & Drainage (2026)

The Town of Oro Valley requires a grading permit for any earthwork exceeding 50 cubic yards, any cut or fill exceeding 3 feet in depth, or any work that alters existing natural drainage patterns. Drainage reports prepared by a registered professional engineer must demonstrate that post-development peak runoff rates do not exceed pre-development rates for the 10-year and 100-year storm events. On-site retention is required for the first-flush storm event and the 100-year, 2-hour design storm. The Town uses Pima County Regional Flood Control District hydrology methods for drainage calculations. Drainage cannot be concentrated or redirected onto adjacent properties without written permission and engineering review. In the Hillside Development Zone, mass grading is prohibited in favor of pad grading that follows natural terrain contours. All grading plans must include a revegetation plan using approved native plant species. The Town inspects grading operations and requires stabilization of disturbed areas within 14 days of completion or seasonal suspension of work.