Resource Management

What's in your Groundwater?

Photo of a pond in some conifers.A GDE what?? A GDE or Groundwater Dependent Ecosystem is defined as a community of plants, animals, and other organisms whose extent and life processes are dependent on access to or discharge of groundwater. Groundwater, which is in aquifers below the surface of the Earth, is one of the Nation's most important natural resources. Common hillslope springs that gush out groundwater fit in this definition as do less well known features such as hypocrenes (buried springs where flow does not reach the surface). In fact, there are over 12 different types of Groundwater Dependent Ecosystems listed in the Groundwater Dependent Ecosystem Inventory Field Guide. Groundwater Dependent Ecosystems can potentially include wetlands, vegetation, mound springs, river base flows, cave ecosystems, playa lakes and saline discharges, springs, mangroves, river pools, billabongs and hanging swamps and near-shore marine ecosystems. These ecosystems can be unique and provide habitat for species not found elsewhere in the landscape.

The Escalante Ranger District of the Dixie National Forest has been doing Groundwater Dependent Ecosystem inventory surveys each summer since 2012 and has surveyed over 85 Groundwater Dependent Ecosystems, many of which have been in the Escalante Subbasin. In addition to determining the type of Groundwater Dependent Ecosystem, some of the parameters measured with the inventories include water chemistry, depth to water table, flow amount, development of peat soils, disturbance to the Groundwater Dependent Ecosystem, and presence of anoxic groundwater (no dissolved oxygen) indicators such as iron flocculation (lumps and clumps). As data collection on these Groundwater Dependent Ecosystems continue there will be a greater understanding of where in the watershed groundwater manifests itself and a pattern may develop as to the type of Groundwater Dependent Ecosystems found based on watershed characteristics.

Photo of a hole in the marshy grass with dark rich soil and a shovel off to the side. Photo of a small narrow crack where water has eroded the soil and a water survey tool on the side.

Photo of a wet marshy meadow at the base of a hill with conifers and deciduous trees.Quick Facts: (source: International Association of Hydrogeologists-

  • Groundwater Dependent Ecosystems have direct value for the human population from fish and plant production, water storage and purification, and indirect value in terms of landscape and/or habitat
  • Degradation of Groundwater Dependent Ecosystems can occur because of anthropogenic modifications to aquifer flow regimes and salinization or pollution of their groundwater