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A stormwater credit trading market for Cook County.

Created in partnership with The Nature Conservancy, (TNC) StormStore™ is a stormwater credit trading market for Cook County. Our team is dedicated to finding innovative solutions to advance equitable stormwater management across the Chicagoland region. In 2020, we launched StormStore to the public through a pilot project with the MWRD. We are currently seeking projects in Cook County to take advantage of the incentives of stormwater trading. Visit to learn more.


Chicago and most suburbs were built before modern stormwater management. Most of our stormwater flows off roofs and pavement into a combined sewer system that is not equipped to handle that much water at once. The overflow causes widespread urban flooding that hits lower-income and minority communities the hardest. Despite our region’s investment in tunnels and reservoirs, we still can’t keep up with the changing climate that is generating more intense storms.  

Today, the Metropolitan Water Reclamation District of Greater Chicago (MWRD) requires developers of new properties to manage stormwater that falls on their sites. In our densely populated region, most stormwater management infrastructure is underground, in the form of costly “gray” infrastructure such as tunnels and reservoirs that have few environmental benefits. Meanwhile, the most flood-prone neighborhoods also tend to be those with very low development activity, which limits new stormwater investment. We’re putting too much stormwater infrastructure where it’s not as needed, at higher cost. 


Stormwater Credit Trading is an innovative, market-based approach to enable more stormwater infrastructure to be built efficiently where it’s needed most. In an area with flooding problems, a supplier can build new stormwater controls not required by a development permit. The stormwater they manage counts as “credits” they can sell. Suppliers typically use natural infrastructure, such as detention ponds, rain gardens, and swales, creating many environmental co-benefits such as new habitats. A qualifying developer can buy the stormwater credits instead of building their own stormwater infrastructure, saving money that they can invest in their project. The credit sale helps the supplier, potentially supporting maintenance. Done well, everyone benefits-–supplier, developer, community, and environment.   

Our partnership has documented the benefits of stormwater credits through research and exchanges with other cities, especially the successful Washington, D.C. program. Now, MWRD has authorized stormwater credit pilots in two Cook County watersheds into 2024. Under the name StormStore, we’re working for the pilots’ success, and helping Cook County manage stormwater equitably and sustainably.


By providing flexibility in meeting stormwater requirements while encouraging stormwater solutions to be located the most beneficial locations in the watershedStormStore has significant potential to provide economic and environmental benefits even at the individual project level. 

Equity through the marketplace 

Encouraging beneficial development 

Providing environmental co-benefits 

Key participants of the StormStore market 

Stormwater regulator 

Credit exchange or market facilitator 

Developers/credit buyers  

Stormwater project creator/Credit sellers 

Learn More

MWRD Pilot in Cook County



Jen Jenkins
Natural Infrastructure Project Manager
The Nature Conservancy
312 580 2138