by Denise Culver


Colorado wetlands provide habitat for more plant and animal species than any other land cover type, yet cover less than three percent of the land area in the state. Although it is often stated that an estimated one million acres of wetlands (50% of the total for Colorado) were lost prior to 1980 (e.g. Dahl 1990; Dahl 2000), it is possible that the true value is much higher. The need for a consistent, comprehensive, scientifically viable survey and classification system of Colorado’s wetlands cannot be overemphasized. The Colorado Natural Heritage Program (CNHP), in cooperation with the Colorado Department of Natural Resources Division of Wildlife (DOW) Wetlands Program has been addressing that need. The cornerstones of CNHP’s efforts are the county-wide wetlands survey program and the wetlands classification system. Status reports for these projects are provided below.

Surveys of Critical Wetlands
Since 1994, CNHP’s Wetlands Program has systematically surveyed and assessed biologically significant wetlands within the following counties: Park, Larimer, Routt, Rio Grande, Conejos, El Paso, Pueblo, Garfield, Mesa, and Summit (see map). Additionally, wetlands in watershed areas such as the Closed Basin of the San Luis Valley (Saguache and northern Alamosa counties) and the Uncompahgre River Basin (Ouray and eastern Montrose counties) have been surveyed. Wetland surveys are proposed for Gunnison, San Juan, La Plata, Costilla, and southern Alamosa counties during the 2002 and 2003 field seasons. The objectives of the surveys are to: 1) identify the locations of the biological significant or critically imperiled wetland plant populations and communities, 2) conduct functional assessments (see below), 3) assess the conservation value of each wetland, and 4) systematically prioritize the wetlands for conservation action. The results of these wetland surveys provide land managers with prioritized lists of tangible conservation targets that provide an opportunity to protect the range of wetland types in Colorado.
Functional assessments are conducted at each of the wetlands surveyed using a qualitative, descriptive method based on the best professional judgment of staff ecologists while incorporating some of the principles of several qualitative methods, such as the hydrogeomorphic (HGM) assessment method (Smith et al. 1995), the wetland evaluation technique (WET) (Adamus and Stockwell 1983), and the Montana Wetland Field Evaluation (Berglund 1996). The twelve functional categories used to assess each wetland are listed below. Additionally, each wetland is classified according to both the Cowardin et al. (1979) and the hydrogeomorphic (HGM) (Brinson 1993) classification systems.

  • Overall functional integrity
  • Flood attenuation and storage
  • Sediment/shoreline stabilization
  • Groundwater discharge/recharge
  • Dynamic surface water storage
  • Elemental cycling
  • Removal of imported nutrients, toxicants, and sediments
  • Habitat diversity
  • General wildlife habitat
  • General fish/aquatic habitat
  • Production export/food chain support
  • Uniqueness


Comprehensive Statewide Wetlands Classification and Characterization (CSWCC) 1999-2002
In 1999, in partnership with the DOW Wetlands Program, CNHP initiated the Statewide Wetlands Classification and Characterization as a key component of the ongoing effort to define a Statewide Wetlands Strategy model for Colorado. The CSWCC grew out of a Wetlands Task Force facilitated by CNHP in 1999. Attendees included representatives of federal, state, county, and city agencies and academia. The CSWCC is a three-phase project designed to develop a tool for community-based conservation and protection of Colorado wetlands and to identify rare wetland plant associations. The three phases are described below.

Survey Map

Phase I (1999-2000)

  1. Collected and synthesized existing wetland data especially from the CNHP Statewide Riparian Classification (Kittel et al. 1999), CNHP wetland inventories (1994-present), and Colorado State University (Dr. D. Cooper) (4,511 plots total).
  2. Identified data gaps and began collection of data from underrepresented wetland types.
  3. Stratified the entire data set into nine hydrogeomorphic (HGM) subclasses, based on hydrogeomorphic classification developed by David Cooper in 1998 (Colorado Geologic Survey et al. 1998, Hupalo et al. 2000).
  4. Posted the results online at

Phase II (2000-2001)

  1. Identify plant associations within each HGM subclass of the stratified data set.
  2. Compile or revise existing plant association abstracts with known ecological and environmental data.
  3. Post results online in November 2001 (Carsey et al. 2001) at

Phase III (2001-2002)

  1. Complete the characterization of the wetland plant associations.
  2. Rank and prioritize wetland plant associations in terms of imperilment and biodiversity significance according to the National Vegetation Classification System (USNVC) (Anderson et al. 1998).
  3. Produce a key to wetland types.
  4. Collect data on poorly-known wetland types such as ephemeral streams, prairie seeps, hanging gardens, and playas.

For more information on CNHP’s Wetlands Program contact Denise Culver, Wetland Ecology Coordinator at             (970) 491-2998       or

Literature Cited
Adamus, P.R. and L.T. Stockwell. 1983. A Method for Wetland Functional Assessment, U.S. Department of Transportation, Federal Highway Administration, Washington D.C.
Anderson, M., P. Bourgeron, M.T. Bryer, R. Crawford, L. Engelking, D. Faber-Langendoen, K. Gallyoun, K. Goodin, D. H. Grossman, S. Landall, K. Metzler, K.D. Patterson, M. Pyne, M. Reid, L. Sneddon, and A.S. Weakley. 1998. International Classification of Ecological Communities: Terrestrial Vegetation for the United States. Volume II. The Nature Conservancy, Arlington, VA.
Berglund, J. 1996. Montana wetland field evaluation form and instructions. Prepared for Montana Department of Transportation, Helena, MT by Morrison-Maierle Environmental Corporation, Helena, MT.
Brinson, M. M. 1993. A Hydrogeomorphic Classification for Wetlands. Wetlands Research Program Technical Report WRP-DE-4. U.S. Army Corps of Engineers, Springfield, VA.
Carsey, K., D. Cooper, K. Decker, and G. Kittel. 2001. Comprehensive Statewide Wetlands Classification and Characterization: Wetland Plant Associations of Colorado-Preliminary Report. Report by Colorado Natural Heritage Program, Fort Collins, CO. Prepared for the Colorado Department of Natural Resources, Denver, CO.
Colorado Geological Survey, Colorado Department of Natural Resources, Colorado School of Mines Division of Environmental Science and Engineering, and Colorado State University Department of Earth Resources. 1998. Characterization and functional assessment of reference wetlands in Colorado; a preliminary investigation of hydrogeomorphic (HGM) classification and functions for Colorado’s wetlands. Report prepared for Colorado Department of Natural Resources and U.S. Environmental Protection Agency, Region VIII, Denver, CO.
Cowardin, L.M., V. Carter, F.C. Golet, and E. LaRoe. 1979. Classification of Wetlands and Deepwater Habitats of the United States. FWS/OBS-79/31. U.S. Fish and Wildlife Service, Washington, DC.
Dahl, T.E. 1990. Wetland Losses in the United States: 1780’s to 1980’s. U.S. Department of the Interior, Fish and Wildlife Service, Washington D.C.
Dahl T.E. 2000. Status and Trends of Wetlands in the Conterminous United States 1986-1997. U.S. Department of the Interior, Fish and Wildlife Service, Washington D.C. 82 pp.
Hupalo, R., D. Culver, and G. Doyle. 2000. Comprehensive Statewide Wetlands Classification and Characterization-Phase I. Report by Colorado Natural Heritage Program, Fort Collins, CO. Prepared for the Colorado Department of Natural Resources, Denver, CO.
Kittel, G.M., E. VanWie, M. Damm, R.J. Rondeau, S. Kettler, A. McMullen and J. Sanderson. 1999. Classification of Riparian Wetland Plant Associations of Colorado. Report by Colorado Natural Heritage Program, Fort Collins, CO to the Colorado Department of Natural Resources, the National Fish and Wildlife Foundation and the U.S. ish and Wildlife Colorado Field Office, Denver, CO.
Smith, R.D., A. Ammann, C. Bartoldus, and M.M. Brinson. 1995. An approach for assessing wetland functions using hydrogeomorphic classification, reference wetlands, and functional indices. Technical Report WRP-DE-9. U.S. Army Engineers Waterways Experiment Station, Vicksburg, MS.

CNHP, located at Colorado State University, is the state’s primary, comprehensive biological diversity data center, gathering information and field observations on rare species and significant plant communities to help develop statewide conservation priorities. CNHP is part of an international network of Natural Heritage Programs that uses Natural Heritage methodology to rank species and plant communities according to rarity or degree of imperilment. The ranking system is based upon the number of known locations and known threats. By ranking the relative rareness or imperilment of species and natural plant communities and the condition of occurrences, the relative importance of associated conservation sites can be rated. This method-ology can facilitate the prioritization of conservation efforts so the most rare and imperiled species and communities may be preserved first.

Colorado Riparian Association