Wetland Assessment: Beyond the Traditional Water Quality Perspective

Abstract

Use of water chemistry or water quality data as the sole indicator to determine if aquatic ecosystems meet restoration objectives or Clean Water Act criteria is not possible for wetland resources because surface water presence varies across wetland types. The 2011, National Wetland Condition Assessment (NWCA) assessed 967 sites representing 25,153,681 ha of wetland across the conterminous US. Surface water could be collected at 537 sites representing only 41% of the wetland population area and under-representing particular wetland types. These results motivated the authors to introduce the concept of aquatic resource quality, the condition of an ecosystem based on the integrated assessment of physical, chemical, and biological indicators, as the goal of monitoring and assessment of aquatic systems. The NWCA is an example of the use of aquatic resource quality. The survey successfully reported on wetland condition using a biotic indicator (the vegetation multimetric index) and the relative extent and relative risk of stressors using 10 physical, chemical, and biological indicators to report on aquatic resource quality. The NWCA demonstrated that aquatic resource quality can be consistently evaluated regardless of surface water presence. Consequently, we recommend aquatic resource quality as the goal of aquatic ecosystem monitoring and assessment.

Using a vegetation index to assess wetland condition in the Prairie Pothole Region of North America

“…Water-quality sampling can be useful for identifying elevated or harmful levels of metals, nutrients, or agrichemicals by comparing observed levels to standards that typically are established by state regulatory agencies. While water-quality assessments can be informative, they do have limitations because standards developed for lakes or streams often do not apply to wetlands; many wetlands have short periods of inundation and even large wetlands dry completely during extended drought ( Euliss et al, 2004 ; Kentula et al, 2020 ). Concentration of some water-quality parameters can vary widely, both within and among years, because of concentration and dilution associated with precipitation, runoff, and evapotranspiration ( Euliss et al, 2014 ; Mushet et al, 2015 ; Hayashi et al, 2016 ).…”