Project Title: Survey of Riparian Habitats Along the Rio Grande

SCERP Project Number: NR98-4

Principal Investigator: Susan Watts

Task Manager's affiliation: University of Texas at El Paso

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Goal: This project will assess the vegetation of existing riparian areas along the Rio Grande between Elephant Butte Reservoir, New Mexico and Ft. Quitman, Texas, for the purpose of providing information that could ultimately improve surface water quality. This proposed project has 5 objectives:

1. Consolidate the best available existing data. Using current and historical data (topographic maps, aerial photos, GIS data, etc.) identify and characterize riparian sites along the Rio Grande, then select riparian areas for study.

2. Conduct field surveys at five-mile intervals along the river and record information about the plant communities using a line transect method.

3. Determine the structure of plant communities in riparian areas based on the number of plant species, their abundance, and the average cover of those species. When data are available, comparisons will document reductions in the size and/or changes in species composition.

4. Test for statistically significant correlations between destruction of riparian habitat and changes in water quality when appropriate data exist.

5. Identify riparian areas with the greatest potential to improve water quality if rehabilitation were undertaken.

The Rio Grande is considered one of North America's most endangered river systems. There is extensive degradation of both water quality and habitat along the length of the river, yet, there is little documentation about how habitat destruction may affect water quality for the Rio Grande. Improvement of surface water quality along the Rio Grande corridor is becoming a critical issue as ground water supplies dwindle and surface water comes under consideration as a source of drinking water for population centers such as El Paso/Juárez. Specifically, the City of El Paso Water Utilities plans to increase its use of surface water; however, during the irrigation season, return flows from agricultural drains increase the Total Dissolved Solids and sulfate concentrations in the river making it unsafe to drink.

The reestablishment of riparian areas along waterways could potentially improve water quality while restoring important habitat for animals as well. Riparian zones are wooded or shrubby areas that line waterways and are characterized by their water-dependent vegetation. The area of focus for this project is the section of the Rio Grande between Elephant Butte Reservoir and Ft. Quitman, because water quality along this section of the river directly impacts the border area from El Paso/Juárez south to Ft. Quitman. The amount of riparian habitat already lost is not known, nor is it known how much still exists. If a riparian area does still exist, historical species composition has likely been altered by the invasion of exotic species, especially salt cedar. We need to know how shifts in species composition and reductions in the size of riparian areas affect water quality.

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