BPA provides a wildlife crediting "ledger" which tracks debits (lost habitat units) and credits (protected and enhanced habitat units). Impact Assessment and HEP report publications are available on Columbia Basin Fish at Search Publications page
In the last two decades BPA has entered into agreements with some of its partners which use acre-to-acre mitigation instead of HU mitigation. These agreements are informed by the assessments and are used to permanently settle BPA’s wildlife obligations for specific dams.
The use of acres as a mitigation “currency” also allows BPA to accurately account for any mitigation work that was done to address the impacts of the dams prior to the passage of the Northwest Power Act; this is referred to a “pre-Act mitigation.”