Wetland health/condition


            Many wetlands exist because of very specific hydrological, biological, geological, chemical, and climatic conditions.  As these conditions change, so do the wetlands.  Some wetlands, such as oxbow lakes and beaver ponds, gradually fill in and are covered by non-wetland plant life.  Other wetland types, such as large bogs and prairie potholes, may exist in a similar state for thousands of years.  Humans have had a dramatic effect on wetlands by altering one or more of the conditions supporting the wetlands, hence many wetlands on the landscape are in some state of ecological distress.  Most often humans have altered the vegetation through grazing or clearing, or altered the hydrology by draining or filling the wetland.  Wetland health or condition can be determined by observing the wetland’s structure (its parts) and function (what it’s doing).  Examples of wetland structure include: water quality, soil condition, geology, hydrology, topography, morphology, carrying capacity, species composition, food web support, and nutrient content.  Examples of wetland function include: surface and ground water storage, recharge, and supply, floodwater and sediment retention, nutrient cycling, biomass production, reduction of erosion, and purification of water.

            There is no one definition that describes a healthy wetland because of the huge diversity of wetland types.  The most reasonable way of describing wetland health is to compare the wetland of interest with other less altered similar sites.  This helps answer the question, “what is the potential of this site?” Another method of discovering and describing degradation is to measure attributes over time.  This kind of data collection could range from comparing historic aerial photographs to more recent ones, to measuring hydrological changes over several years.  If the wetland’s structure and function no longer measure up to its potential, it is said to be unhealthy.

For information on assessing wetland health in Montana, See these sites: 

Bitterroot Restoration's Riparian and Wetland Research Project and UM's Hydrogeomorphic Method.