These programs allow developers (and others) to purchase credits in a publicly-owned Mitigation Bank which uses the proceeds to enhance, restore, preserve or create a needed natural resource, such as a wetland or forest buffer. The developers may use these credits to fulfill mitigation requirements for impacts in other locations, generally within the same watershed.

A mechanism being used in the US which encourages people to invest in nature conservation, such as protecting, restoring or even creating wetlands, in return for being able to sell 'credits' to those who destroy valuable habitats. It's part of the process of internalising environmental costs which have often been externalised (that is, do not appear on the balance sheet) and therefore ignored.

the creation of a fund that enables damage associated with resource use or development to be partially offset by reclaiming, restoring or permanently protecting another area.