Watershed Symposium 2018

Wetlands in the Watershed: Health, Stressors, Losses, and Function

The Utah Geological Survey recently completed a field study and landscape analysis of wetlands in the Jordan River watershed. This talk will discuss the condition, common stressors, and estimated losses of wetlands in Salt Lake County as well as some of the important functions that these wetlands provide.

Full Abstract
Wetlands play a vital and sometimes unseen role in protecting the quality of life of people living in Salt Lake County. The Utah Geological Survey recently completed a field study and landscape analysis of wetlands in the Jordan River watershed. Most of the wetlands surveyed for this project in the County were in the Great Salt Lake and Wasatch Front regions, which will be the focus of this talk. Common threats to wetlands in this region include water quality stressors, hydrologic alteration, and non-native plant species. Wetlands frequently receive water from sources impacted by development runoff and point source discharge and, in the Wasatch Front, half of all wetlands receive direct stormwater inputs. Hydrology at most Great Salt Lake wetlands is controlled by management practices via impoundments, ditches, and control structures, either directly within impoundments or indirectly due to overflow or release from impoundments whereas Wasatch Front wetlands are less directly managed, but still altered through ditching, berms, and impervious surface. Noxious weeds are very abundant in wetlands in the County, covering almost 25% of Great Salt Lake and over one-third of Wasatch Front wetlands, which much of the cover from the aggressive grass species Phragmites australis (common reed). Despite these stressors, wetlands in the region provide many important functions. Almost all the studied wetlands likely play a role in helping improve water quality. Wetlands also provide important habitat not only for migratory and nesting birds in the world-renowned Great Salt Lake wetlands, but also for birds along the Wasatch Front and for a diversity of mammals, amphibians, reptiles, and fish. Wetlands also support recreational opportunities such as hunting and bird watching and provide a scenic backdrop for people out recreating. Landscape analysis shows a large change in wetland area from when wetlands were originally mapped in the region, which occurred primarily in 1998. Only 46% of the area mapped as wetlands in the older spatial data from the Wasatch Front appears to be wetlands today; about one-third of the mapped wetlands have been replaced by development. Losses around Great Salt Lake were smaller by percentage (~13%), but much larger in terms of total area (~5600 acres). However, it is unclear how much of the change is due to changes in aerial imagery interpretation, hydrologic alterations, or other alterations; little of the change around Great Salt Lake could be attributed to development.