The ratio the Corps of Engineers seek is usually about 1 to 1.5 for each wetland acre the developer destroys. The cost of restoring 1.5 acres of wetlands in the receiving area is paid out. The first question with mitigation banking is if it is really necessary in the first place. The second question is that wetlands restoration is an inexact science. It is very difficult to recreate all the functions of the wetlands.
Mitigation looks good on paper but there are some issues that are hard to resolve.
Developers could do damage in one watershed while they might achieve mitigation in another. Most wetlands are not reconstructed well, and it takes up to 30 years to develop a forested wetland. He also said that restricting the total number of sites where mitigation takes place made monitoring easier and therefore assuring compliance.