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Water quality patterns for conterminous USA wetlands elucidated by EPA’s National Wetland Condition Assessment
Citation:
Trebitz, A. AND A. Herlihy. Water quality patterns for conterminous USA wetlands elucidated by EPA’s National Wetland Condition Assessment. 14th National Monitoring Conference, Green Bay, WI, March 10 - 14, 2025. https://doi.org/10.23645/epacomptox.28680458
Impact/Purpose:
This presentation uses data collected from the 2016 and 2021 EPA Office-of-Water led National Wetland Condition Assessment to illustrate that water quality in wetlands is substantially influenced by anthropogenic activities on the wetland perimeter and watershed. Such anthropogenic impacts are well documented for lakes and streams but are relatively unexplored in wetlands, especially on a continental scale. This presentation is part of a larger ORD effort to support Office of Water in the planning of and subsequent analysis of NARS surveys across the USA.
Description:
The EPA’s National Wetland Condition Assessment (NWCA) characterizes a suite of water quality metrics as part of its 5-year sampling cycle for wetlands across the lower 48 USA states. Analyses to date have documented considerable water quality variability – as would be expected over a broad geographic and hydro-morphologic range – but also a consistent association to local and landscape anthropogenic pressures. For example, water samples obtained from inland wetlands in 2011 and 2016 spanned pH from <4 to >9 and three to five orders of magnitude in ionic strength (chloride, sulfate, conductivity), nutrients (total N and P), turbidity, planktonic chlorophyll, and dissolved organic carbon (DOC). Nutrients were elevated in association with heavy agricultural/urban landuse, chloride was elevated in wetlands near major roadways in northern-tier states, and sulfate was notably elevated in wetlands in coal-mining watersheds. Furthermore, ionic strength and nutrients increased with increasing landuse pressure not only in riverine and lacustrine wetlands but also in flats and closed depressions, which indicates landscape connectivity even in the absence of visible surface streams. Analyses that expand to 2021 NWCA data and more directly link measured nitrogen and phosphorus to modelled watershed loadings are underway. The views expressed in this abstract are those of the author(s) and do not necessarily represent the views or policies of the U.S. Environmental Protection Agency.
URLs/Downloads:
DOI: Water quality patterns for conterminous USA wetlands elucidated by EPA’s National Wetland Condition Assessment
WATER QUALITY PATTERNS FOR CONTERMINOUS USA WETLANDS ELUCIDATED BY EPAS NATIONAL WETLAND CONDITION ASSESSMENT 508.PDF (PDF, NA pp, 994.684 KB, about PDF)