Watershed Planning Toolbox

Wetland functions at the watershed scale depend on many factors, including landscape position, wetland type and hydrology, land use, and underlying geology. CNHP has enhanced the National Wetland Inventory dataset to include Landscape, Landform, Water Flow Path, and Waterbody (LLWW) attributes, along with a variety of modifiers for unique wetland types and human use. These additional attributes provide a more comprehensive view of the diversity of Colorado wetland types, and a foundation for assessing and modeling wetland functions at the watershed scale. Wetland types are grouped by wetland hydroperiod (corresponding with Cowardin hydrologic regimes), vegetation classes, hydrogeomorphic class, and dominant water flow path. Additional layers include potential historical wetland areas for parts of the state, along with formerly irrigated lands, waterbody permanence, and statewide percent hydric soils by soil map unit.

Wetlands are located at the interface between terrestrial and aquatic environments, and are often hotspots for a diverse array of terrestrial and aquatic wildlife and plants, including rare species. CNHP modeled rare wetland species support and overall biodiversity conservation, along with likely habitat for aquatic invertebrates, shorebirds, and waterfowl using wetland attributes including hydroperiod, vegetation, and land use. Geospatial data layers from outside groups and agencies include Gold Medal fish streams, barriers to fish passage, Important Bird Areas, Bird Habitat Conservation Areas, and priority watersheds for CPW Tier 1 fish species.

Wetlands perform a variety of water quality functions at the watershed scale, including removing and storing nutrients, metals, and carbon, along with regulating the temperature of surface water. Likely wetland water quality functions were modeled using a literature review of how different types of wetlands perform water quality functions, including associations between functions and wetland hydrogeomorphic attributes like landscape position, landform, and dominant water flow paths. Supporting geospatial data layers include potential sources of pollutants, such as mines and oil and gas well, as well as state-listed Outstanding Waters, 303(d) water quality impaired waters, and Watershed Plans related to addressing nonpoint source pollution.

Wetlands support clean water along with providing flood attenuation, stream flow maintenance during dry periods, surface water storage, groundwater recharge, sediment capture and retention, and streambank and shoreline stabilization. Floodplain, or riparian wetlands including beaver pond and meadow complexes may provide all of these functions. CNHP modeled likely water quantity and geomorphic functions by reviewing literature on how wetlands intercept, store, and release water and sediment in the landscape, and crosswalking these processes to wetland landscape positions, landforms, dominant water flow types, and vegetation. Supporting geospatial data layers include statewide floodplains, alluvial aquifers, decreed instream flows and lake levels, historic fire perimeters, irrigated lands, surface water diversions, and groundwater wells.

CNHP has worked with the Arkansas Headwaters Wetland Focus Area Committee to develop priority areas for wetland conservation and restoration, many of which overlap CNHP’s wetland-based Potential Conservation Areas. Priority areas include large wetlands that have been degraded or converted to upland, and where conservation or restoration activities are likely to benefit adjacent natural areas, improve ecological functions like wildlife habitat and downstream water quality, and be technically feasible. Additional large-scale priority areas in the Toolbox include the Upper South Platte subbasin/South Park and playas in the Great Plains. We hope to add additional layers in the future, as conservation groups identify focus areas for wetland conservation and restoration.