The Stormwater Credit Exchange (SCE) is a clearinghouse service that allows participants who reduce their "stormwater runnoff footprint," the total stormwater runnoff from a property during a storm event, to market those credits. Participants who do not reduce their footprint can make offers to purchase offset credits via the SCE.

Every time a stormwater runnoff credit is purchased or sold via the SCE, the credit holder will be designated with a Stormwater Retention Credit (SRC) certifying that the holder sold or purchased the credit. One SRC = 1 gallon of retention for one year. SCE is establishing a baseline rate for one SRC that equals $1. It is for reference purposes only because the marketplace will establish the true price. SRCs can be bought and sold though the SCE at a miniumum rate of $1 per SRC.

Under the DC Department of the Environment (DDOE) Stormwater Retention Credit Trading Program, all regulated development sites would have a net retention requirement, which could be achieved through a combination of on-site practices. All regulated sites would be required to achieve a minimum amount of their 1.2" retention volume on site.

The SCE is a private sector complement to a public sector program.