Central Oklahoma Stormwater Alliance (COSWA)  is an organization of MS4s in the Oklahoma City metropolitan area which allows participating MS4s to pool resources to satisfy permit obligations on a regional level.

What We Do

We participate in events and outreach to help teach the local community about water quality and local stormwater issues.

We promote the use of rain barrels to help mitigate pollutant discharges and potential downstream flooding.

We work collaboratively to increase public awareness of stormwater and other environmental issues.

Regulated MS4s in Oklahoma


Phase I MS4s


Phase II MS4s




Non-Traditional MS4s

Latest News and Updates

Rain Barrels 101

Are you looking for a quick, easy project that you can do while staying safely socially distanced at home? City of Norman’s community volunteer Amanda Nairn will walk you through the basics of setting up a rain barrel for your garden just in time for summer!

Industrial Stormwater Webinar

The City of Oklahoma City Storm Water Quality Management Division will host a WEBINAR geared toward Industrial Storm Water permittees. The webinar will begin at 10:00am on Thursday, February 27th, 2020.  This webinar is FREE and is expected to last approximately 30-40 minutes, with Q&A. The topic for this webinar will include: Industrial Storm Water Training… Continue reading Industrial Stormwater Webinar