Do I need a Stormwater Permit?

You need a Maricopa County Stormwater Permit If the following two conditions are met:

1. The project is located within the Urbanized Unincorporated Area (See information below)


2. A project disturbs 1 or more acres of land OR a project is less than one acre but is part of a larger plan of development* that disturbs one or more acres of soil.

*A common plan of development is a contiguous area where separate and distinct construction actives may be taking place at different times on different schedules, but are under one common plan. For more information, visit our What Is a Common Plan of Development page.


To determine if your specific project is within the unincorporated urbanized area of Maricopa County, follow these instructions:

 1. Click on the link to PlanNet to bring up the Map Viewer

 2. Once on PlanNet select "Communities"  on the side bar. Under Communities ensure only "Cities and Towns" is selected.

3. On the side bar select "Demographics." Under Demographics ensure only "Urbanized Unincorporated Areas" is selected.

4. Next you may type in your parcel number.* On the top bar select "APN" (it is in a square box). Type in your parcel number and hit "locate."

5. If your parcel is located within the blue crossing-hatching areas, your project is within the Urbanized Unincorporated Area and may require a permit.

 *Don't have a parcel number(APN)? Please visit the Maricopa County Assessor's Office and type the project address into the search bar. This should populate an APN or parcel number. Still having problems, or have parcels that are being split? Please contact our department at 602-506-5557 and we can assist you. 

  1. Stormwater Program

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