Stormwater Management: Green Valley vs Marana
How do stormwater management rules compare between Green Valley, AZ and Marana, AZ?
Marana has fewer restrictions than Green Valley.
Green Valley, AZ
Pima County
Pima County enforces stormwater management through the Pima County Regional Flood Control District (RFCD) and the county MS4 permit under the Clean Water Act. The Sonoran Desert monsoon season (July-September) drives strict drainage and retention requirements. All new development must retain the first inch of stormwater on-site per county standards.
View full Green Valley rules →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 →Key Facts Comparison
| Fact | Green Valley | Marana |
|---|---|---|
| Authority | Regional Flood Control District | - |
| Retention Standard | First 1 inch on-site | - |
| Permit Trigger | 1 acre or more disturbance | - |
| Monsoon Season | July through September | - |
| Contact | RFCD 520-724-4600 | - |
| 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) |
Highlighted rows indicate differences between cities.
Green Valley FAQ
What stormwater retention is required in Pima County?
New developments must retain the first inch of stormwater on-site. This is based on the 100-year, 2-hour storm standard. Retention basins, bioswales, and permeable surfaces are common compliance methods.
Do I need a stormwater permit for construction in Pima County?
Yes, if your project disturbs one acre or more. You must file an AZPDES Notice of Intent with ADEQ and implement a Stormwater Pollution Prevention Plan (SWPPP) before breaking ground.
Who manages stormwater in unincorporated Pima County?
The Pima County Regional Flood Control District (RFCD) manages stormwater infrastructure, floodplain regulations, and drainage standards. Contact them at 520-724-4600.
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).
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