Mitigation Ratio Calculator

Presentation on Mitigation Ratio Calculator by Dennis King of the University of Maryland (June 4, 2009).  The national goal of "no net loss" of wetlands means that wetland development permits are usually issued only if permit-seekers agree to "mitigate" lost wetland functions by undertaking wetland creation, restoration or enhancement projects, or by to preserving at-risk wetland areas.  Since each acre of mitigation may not fully compensate for each acre of impacted wetland a "mitigation ratio" is usually used to establish the number of acres of mitigation required per acre of wetland impact.  Besides establishing a kind of environmental quality/quantity tradeoff, the mitigation ratio has an enormous effect on the cost of providing mitigation. For this reason, and because resource agencies often establish mitigation ratios on the basis of ad hoc criteria or obscure biophysical measurements or by employing politically negotiated look-up tables, the mitigation ratios recommended by resource agencies are often challenged by permit seekers.  The Mitigation Ratio Calculator is a framework, formula, and associated spreadsheet program that resource agencies can use to develop wetland mitigation ratios that are based on scientific and economic principles, can be applied using "best available" information, result in mitigation that will achieve the "no net loss" wetland goal, and are capable of withstanding technical and legal challenges.  The approach can be applied usefully whether mitigation takes the form of wetland creation, restoration, enhancement, or preservation, or some combination.  Similar tools are being developed to assess and compare other types of environmental investments and trades, such as carbon sequestration trades that involved reforestation.  Read a full report on the tool at and read more about wetland assessment procedures used at

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