What is the Best Wetland Assessment Tool? A Discrimination of Overlapping Assessment Approaches.

Abstract

There are over 700 aquatic ecological assessment approaches across the globe that meet specific institutional goals. However, in many cases, multiple assessment tools are designed to meet the same management need resulting in a confusing array of overlapping options. Here we look at six riverine wetland assessments currently in use in Montana, USA, and ask which tool: 1) best captures the nuance of condition across a disturbance gradient and 2) has the most utility to meet the largest regulatory need. We used descriptive statistics to compare wetland assessments (n = 16) across a disturbance gradient determined by a landscape development index. We also used factor analysis to determine if each tool’s metrics correspond to its overall results and performed as designed. We interviewed regional wetland managers (n = 56) to determine the extent of their use of each of the six tools and how well they trusted the information the assessment tool provided. We found that the Montana Wetland Assessment Methodology best measured the range of disturbance and had the highest utility to meet Clean Water Act (CWA§ 404) needs. Montana Department of Environmental Quality was best for the CWA§ 303(d) & 305(b) needs. The US Natural Resources Conservation Service’s Riparian Assessment Tool was the third most used by managers but was the tool that had the least ability to distinguish across a disturbance, followed by the US Bureau of Land Management’s Proper Functioning Condition. Many tools had internal mechanics that hindered the tool’s ability to act as it was designed.