Stormwater Management: Marana vs Oro Valley
How do stormwater management rules compare between Marana, AZ and Oro Valley, AZ?
Marana has fewer restrictions than Oro Valley.
Marana, AZ
Pima County
Marana enforces stormwater management requirements under its MS4 NPDES permit and the Land Development Code. New development must include retention/detention basins, and post-development runoff must not exceed pre-development levels.
View full Marana rules →Oro Valley, AZ
Pima County
Oro Valley enforces stormwater management through its MS4 permit under the Clean Water Act. New development must retain the first-flush storm event on site.
View full Oro Valley rules →Key Facts Comparison
| Fact | Marana | Oro Valley |
|---|---|---|
| Permit | MS4 NPDES permit | - |
| Retention | Required for new development | - |
| Construction Sites | SWPPP required for 1+ acre disturbance | - |
| Flood Control | Pima County RFCD coordination | - |
| LID | Encouraged (permeable, swales, harvesting) | - |
| Permit Type | - | EPA Phase II MS4 via ADEQ |
| Construction Threshold | - | 1 acre disturbance triggers AZPDES |
| Retention Standard | - | 100-year, 2-hour storm on site |
| Water Harvesting | - | Required for new development |
| Illicit Discharge | - | Prohibited to storm drains |
Highlighted rows indicate differences between cities.
Marana FAQ
Does Marana require stormwater retention for new construction?
Yes. The Land Development Code requires retention/detention facilities for new development. Post-development runoff must not exceed pre-development levels.
Do I need a stormwater permit for a construction project in Marana?
Construction sites disturbing one acre or more must obtain ADEQ Construction General Permit coverage and implement a Stormwater Pollution Prevention Plan (SWPPP).
Oro Valley FAQ
Can I drain my pool into the street in Oro Valley?
No. Pool water discharge to the storm drain system is prohibited as an illicit discharge. Pool water must be dechlorinated and directed to a landscaped area or sanitary sewer with utility approval.
Do I need a stormwater permit for a home addition?
Most single-lot residential projects do not trigger the one-acre AZPDES threshold, but you must ensure post-construction drainage does not impact neighboring properties. The building permit process reviews drainage plans.
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