Great Salt Lake Wetland Condition Assessment
Diane Menuz, Ryhan Sempler, Jennifer Jones
wetland, great salt lake, monitoring, assessment, condition, groundwater, epa, wetland program development, core element, Utah Geological Survey, UGS, #CD96811101, EPA, Wetland Program Development Grant
Wetlands are an important component of the Utah landscape, providing beneficial services including flood control, water purification, and wildlife habitat. The largest concentration of wetlands in the state is along Great Salt Lake, a hypersaline terminal lake in northern Utah. Great Salt Lake wetlands are internationally recognized for their importance as migratory and breeding bird habitat and are one of only 23 areas considered wetlands of hemispheric importance (the top designation) by the Western Hemisphere Shorebird Reserve Network (http://www.whsrn.org/sites/list-sites). These wetlands are also socially and economically important for the hunting and bird-watching opportunities they provide (U.S. Fish and Wildlife Service and U.S. Census Bureau, 2013).
Great Salt Lake wetlands have been subject to high levels of anthropogenic manipulation, beginning most prominently with groundwater pumping and water diversions that severely reduced wetland acreage by the early 1900s. Extensive sections of the remaining wetlands have been impounded to allow for close control over the water that is still present. Many of the wetlands are located in areas that have undergone, and are continuing to undergo, rapid urbanization, with over 45% population growth forecast between 2010 and 2040 for the three most urban counties adjacent to the wetlands (Davis, Salt Lake, and Weber, http://governor.utah.gov/DEA/projections.html). Urbanization contributes additional stress related to water availability and water quality. The invasive grass species, Phragmites australis ssp. australis (common reed), is another important stressor that that has replaced much of the native wetland vegetation around Great Salt Lake (Kulmatiski and others, 2011).
In 2013, the Utah Geological Survey (UGS), with a grant from the U.S. Environmental Protection Agency (EPA), undertook an assessment of the current condition and presence of stressors at Great Salt Lake wetlands to better understand this important and threatened ecosystem. The project was specifically focused on palustrine emergent wetlands, which are nontidal wetlands characterized by primarily perennial, erect, rooted, herbaceous hydrophytic vegetation that is present for most of the growing season (Cowardin and others, 1979). Data were collected at sites using a rapid assessment method designed to evaluate important indicators of wetland health during a short field survey. Additional information was obtained from more intensive vegetation data collection. This assessment work occurred in conjunction with two related projects, which focus on developing a rapid assessment protocol for use on wetlands throughout the state and developing a model of surface flow paths around Great Salt Lake. Much of the data collected for this project will be used to inform on-going work on these related projects.
This project has three major components:
1. Conduct a field-based assessment of the condition of palustrine emergent Great Salt Lake wetlands at sites experiencing a broad range of natural and anthropogenic states.
Approach: Surveyed sites using the rapid assessment protocols that are being tested and developed by UGS. Selected a random sample of sites to survey and supplemented with additional, subjectively chosen sites in order to ensure that we captured variability in management regimes, surrounding land use, and other states.
Goal 1: Collect information on the condition of Great Salt Lake wetlands and surrounding land use.
Goal 2: Use field experience to inform on-going rapid assessment protocol development by, for example, determining which metrics are difficult to evaluate or not relevant for Great Salt Lake wetlands.
Goal 3: Evaluate the relationship between stressors observed in the field and components of wetland condition, such as hydrologic and vegetation condition.
2. Obtain detailed plant community data at field sites.
Approach: Collected data on the presence and percent cover of all plant species found in survey plots.
Goal 1: Contribute data on wetland plant species distribution and abundance to a database for further development of plant-based metrics in the state of Utah, including state-specific coefficient of conservatism values.
Goal 2: Evaluate the relationship between plant community metrics and site attributes, including natural and anthropogenic variables and wetland condition as evaluated in component 1.
3. Apply a landscape approach to evaluate potential threats and stressors to Great Salt Lake wetlands.
Approach: Developed a model of wetland stressors at surveyed field sites using available spatial data for predictor variables.
Goal 1: Determine the types of stressors evident on the landscape that may affect wetland condition.
Goal 2: Evaluate the relationship between landscape stressors at different spatial scales and field survey data, including overall wetland condition and plant community metrics.
Goal 3: Use information obtained from this analysis to inform development of an approach to modeling wetland condition at the landscape level that can be applied to all Great Salt Lake wetlands.