Assessment & Monitoring > Basinwide Assessments

Basinwide Wetland Assessments

Since 2008, CNHP has conducted field surveys to assess the condition of wetlands in three major river basins. Our goal is to survey each of the major river basins on a rotating schedule every 10 to 15 years. Results from these surveys help guide restoration priorities for Colorado Parks and Wildlife’s Wetland Program and other conservation partners.

Map of CNHP's Basinwide Assessments

Rio Grande Headwaters: The pilot basinwide assessment took place between 2008–2011 in the Rio Grande Headwaters River Basin in south central Colorado. The study followed the EPA’s Level 1-2-3 framework of wetland assessment, using various degrees of data collection intensity to estimate the condition of wetlands. A Level 1 profile of wetlands based on National Wetland Inventory (NWI) mapping and the wetland Landscape Integrity Model showed that there were 282,804 acres of wetlands and waterbodies in the basin and that these acres are unequally distributed across geographic regions and major land owners. More wetland acres were concentrated within the San Luis Valley, though these acres were more likely to be irrigated and face more severe stressors. Wetlands in the mountainous areas of the basin were more diverse and less stressed. Field-based Level 2 & 3 assessments concurred with patterns seen in the Level 1 GIS exercise. Marshes and saline wetlands, found more commonly at lower elevations, had lower condition scores in general. Fens and riparian shrublands, found more commonly at higher elevations, had higher condition scores. Wet meadows were the most common wetland type surveyed and spanned both the geographic range of the study area and the condition gradient.

Rio Grande results graph

North Platte: The second basinwide assessment took place between 2009–2011. Similar to the Rio Grande, various degrees of data collection intensity were used to estimate wetland condition. A Level 1 profile showed that there were 138,043 acres of wetlands and waterbodies in the basin. Within the basin as a whole, 59% of wetland acres were irrigated and these acres were overwhelmingly (96%) freshwater herbaceous wetlands. Among all herbaceous wetlands, 75% were irrigated. Wetlands in the basin were disproportionally concentrated in the North Park valley, where flood irrigation for hay production creates vast expanses of wet meadow. Wetlands actively managed as hay pastures were removed from the field sampling to concentrate on the more naturalized wetlands of the basin. Population level estimates indicate that 82% (44,409 acres) of non-irrigated wetlands were A- or B-ranked based on Level 2 EIA scores, meaning they are in reference condition or deviate only slightly from reference condition. An additional 17% (9,096 acres) were C-ranked, meaning a moderate deviation from reference condition that would warrant some type of management or restoration. Few wetlands had signs of severe hydrologic alteration that would significantly threaten wetland health. There was little substrate disturbance and no obvious visual signs of water quality impairment. Biotic condition was generally high. Very few noxious weeds were observed, though wetlands that were former hay fields or adjacent to active hay field contained significant cover on non-native species. The North Platte assessment also evaluated the potential habitat quality for dabbling ducks.

North Platte results graph