AN EVALUATION OF WETLAND COMPENSATORY MITIGATION IN THE NEW YORK GREAT LAKES BASIN

Abstract

An ongoing priority for EPA’s Wetlands Program is to determine the effectiveness of compensatory mitigation at offsetting impacts to wetlands and meeting the goal of ‘no net loss’ of wetland functions. The Army Corps of Engineers is also tasked to ensure that required compensatory mitigation actions are being taken for impacts to waters of the United States under the Clean Water Act-Section 404 permit program. The purpose of this study was to provide information about the success of compensatory creation and restoration mitigation efforts for permitted impacts in the New York Great Lakes region of the Buffalo Corps District. A review of the District’s records was performed in order to identify where Section 404 wetland impacts have been occurring and to examine the extent to which wetland mitigation sites have been successful in terms of acreage achieved, established plant community type, and invasive species colonization. In addition, percent cover of invasive species at mitigation sites was examined against landscape setting to see whether this was related to success. A number of recommendations were made concerning possible improvements to permitting, data management, and mitigation project monitoring and reporting. At the onset of this study, data retrieval proved to be difficult because project files were often incomplete. At mitigation sites, a disproportionate amount of emergent and emergent/open water systems were proposed to replace scrub-shrub and forested communities. Thus, functional replacement may be unlikely in those cases. Percent cover of invasive species increased with urbanization, possibly reflecting effects of disturbance on fostering invasive plant species colonization. Success in obtaining no net wetland loss is reliant upon the ability to issue permits with conditions that ensure that functions are properly replaced, and also on continued follow up compliance monitoring of these mitigation projects.