What Is a Mitigation Bank?

A mitigation bank is a site that has been restored or protected and approved by regulators to sell compensatory-mitigation credits. When a project unavoidably damages a wetland, stream or protected species' habitat, the developer buys credits from a bank to offset the harm rather than building and monitoring the restoration themselves. It is the “polluter pays, expert restores” model.

Two federal laws drive the demand. Under the Clean Water Act §404, impacts to wetlands and streams must be offset — the “no net loss” policy. Under the Endangered Species Act, impacts to listed species' habitat must be offset, and those offsets come from conservation banks. A bank lets a developer satisfy the requirement by buying a finished, agency-approved credit instead of taking on restoration risk that runs for decades.

A credit is the unit a bank sells. Credits are released in stages as the site meets its ecological performance milestones, and withdrawn as they are sold against permitted impacts. What remains is what you can buy today. Two rules decide which credits you are allowed to buy at all:

• Service area — a bank may only serve projects inside its approved geographic boundary, usually a watershed or a species range. This is a legal boundary drawn on a map, not a matter of convenience or distance.
• In-kind — the credit type must match the impact. Wetland credits offset wetland impacts, stream credits offset stream impacts, species credits offset that species' habitat. They are not interchangeable: a wetland credit will not satisfy a stream impact, however many of them a bank holds.

Available across approved open-market banks nationally: 403,550 Wetland credits at 1,434 banks · 7,086,583 Stream credits at 766 banks · 105,788 Species credits at 123 banks · 941 NRDA credits at 4 banks · 10,466 Mixed credits at 23 banks. The classes are never added to each other — they offset different resources, and a combined figure is a number nothing transacts against. Within a class they are added: RIBITS records the assessment method each bank's credits were sized by, and that method travels with the bank on its own listing.

1. Identify the credit type your permitted impact requires — this comes from the permit, not from the bank.
2. Find a bank whose service area covers your site. The bank search does this from an address, coordinates or a watershed.
3. Check the bank's available credits for that class. A bank can be approved and still hold nothing you can buy.
4. Contact the sponsor directly to purchase. The credits are then recorded against your permit in the federal ledger.

Prices run from a few hundred dollars for some stream credits to several hundred thousand per wetland credit, depending on the credit type, the local market and how the credit is measured. No public source publishes what bank credits trade for. The one set of officially published prices in this market is the in-lieu fee rate schedules — administrative list prices, useful as an anchor but not what bank credits trade for nearby.

Mitigation banks are one of three offset routes. With an in-lieu fee program you pay a sponsor — often a state agency or a conservation non-profit — which carries out the mitigation later; 110 such programs are registered nationally, and 22 of them publish a rate schedule. With permittee-responsible mitigation you build and monitor the offset yourself. Regulators generally prefer banks first, precisely because the restoration already exists and has already been approved.

Browse banks, availability and watershed coverage for a state: