Habitat Modeling for Rio Grande Silvery Minnows
     The Rio Grande Silvery Minnow (RGSM) Hybognathus amarus is listed as endangered under the Federal Endangered Species Act and by the states of New Mexico and Texas and the Republic of Mexico. RGSM were historically abundant throughout the Rio Grande Basin, as far upstream as Abiquiu and Santa Rosa (Pecos River), and downstream as far as Brownsville, TX. RGSM now only occur downstream of Cochiti Dam to the tailwater of Elephant Butte Reservoir (designated as critical habitat). The decline of this species is primarily attributed to hydrologic manipulations caused by extensive diversions and impoundments. The objective of this study was to develop a two-dimensional, unsteady habitat evaluation model to evaluate RGSM habitat suitability over a range of streamflows. (top)

Impact of EDC’s on Aquatic Communities
    Over the past decade, a growing body of evidence suggests that numerous chemicals (e.g., endocrine disrupting chemicals; EDC’s), both natural and man-made, may interfere with the endocrine system and produce adverse effects in humans, wildlife, fish or birds. Recently, issues of EDC’s related to pharmaceuticals have attracted a lot of attention because exposure to low levels of these compounds may modulate normal endocrine function of aquatic organisms which is difficult to detect.  A recent study of Lake Mead common carp found evidence of endocrine disruption in both males and females such as altered ratios of sex hormones.  Our research focuses on investigating the chronic and short term impact or lack thereof of EDC’s on life history traits, particularly fecundity and offspring sex ratios of invertebrates such as Daphnia. Daphnia provides a good test species for such studies not only due to its strategic placement in the food web but also the fact that sex induction is environmentally stimulated in Daphnia. Filter feeders like Daphnia may also be helpful in understanding bio-accumulation potential of these potentially lethal chemical compounds. (top)

Impact of Linear Anionic (LA-PAM) on Daphnia

Storm water BMPs for Arid Regions:

    Best Management Practices (BMPs) are effective, practical, structural or nonstructural methods which prevent or reduce the movement of sediment, nutrients, pollutants, or debris from land to surface or ground water. These practices are developed to achieve a balance between flow control and water quality protection.  Most BMPs that are intended for controlling stormwater runoff were developed in wet and humid climates and are therefore untested for arid and semi-arid regions of the Western US.  In arid regions, (1) rainfall is infrequent and of short duration, (2) native soils are not protected by vegetation, (3) dry channels (washes) naturally contain a large volume of sediment, and (4) most catchments do not discharge to a perennial stream or lake.  Given these hydrologic and geomorphologic differences between the regions, it is reasonable to expect that sediment control BMPs in arid zones may perform poorly. This project will evaluate the effectiveness of stormwater BMPs for arid regions. (top)

Sediment Transport issues in Rio Salado, Rio Grande and Las Vegas Wash:

    Sediment is the largest contaminant of surface water by weight and volume and has been identified by the United States Environmental Protection Agency as the number one problem threatening America's waterways. Today, the most pressing sediment-related problems are associated with environmental questions such as the transport and fate of attached pollutants, effects of sediment on aquatic biota and their habitat, and changes in sediment transport related to land use change. Understanding the fate of sediment-bound pollutants requires an understanding of the transport and deposition of sediments. Our studies have focused on source and transport of sediments in Las Vegas Wash (Las Vegas, NV), Rio Salado (Phoenix, AZ) and Rio Grande (Albuquerque, NM) by 2D numerical models and field investigations. (top)

Vegetation and Flood Control in Southern California Rivers:

    Within many flood control channels in the Southwest US, vegetation has become established, reducing the channels’ conveyance capacity below the original project objectives and greatly increasing the risk for loss of lives and property damage in the case of large flood events. Vegetation overgrowth is a result of several factors including endangered species issues, public perceptions of aesthetics, and lack of maintenance. Our research will study vegetation washout as a function of hydraulic flow conditions in three rivers in southern California: Los Angeles, San Luis Rey, and Santa Clara Rivers. We ultimately will develop a technical guidance for the estimation of washout and associated hydraulic roughness. (top)
 

Non Point Source Pollution in Las Vegas Wash:

    Non point source (NPS) pollution, unlike pollution from industrial and sewage treatment plants, comes from many diffuse sources discharging into lakes, rivers, wetlands, coastal waters, and groundwater. According to the EPA, NPS remains the largest source of pollution of water bodies in the United States. Water quality in Lake Mead, including Las Vegas Bay, is heavily influenced by water discharging from the Las Vegas Wash. Municipal wastewater effluent, storm water, urban runoff, and shallow ground-water seepage from Las Vegas Valley all contribute to nutrient loads in the Wash. All of these nutrient sources will continue to grow with the population of the Valley. The objective of our study is to describe the spatial and temporal patterns (e.g., various land uses) of NPS pollution, mainly nutrients and total suspended solid loads, in the Las Vegas Wash system. (top)

C, N Stoichiometric profile of Desert Soils:

    Arid and semi-arid ecosystems comprise 30-40% of Earth’s terrestrial biomes and are increasing in area (Dregne 1991). Low rainfall is a primary constraint on biological activity in such systems.  Soil water acts as a medium for the movement and diffusion of substrates used by soil micro-flora and fauna.  Water in soil pores also serve as a barrier for the movement of oxygen. Soil moisture thus exerts a significant control on the function of soil ecosystems.  In addition to water, the total Carbon (C) and Nitrogen (N) capital of arid and semiarid ecosystems is a broad indicator of its productivity, material cycling, and biological carrying capacity (Asner et al. 2003). Changes in available C and N pools may affect nutrient dynamics by changing the size and composition of the soil organic matter pool, either through changes in litter chemistry or quantity, or in rates of belowground production (Prescott et al 2000). The main objective of this study is to understand the spatial distribution of C: N stoichiometry; the relationship between moisture content and C, N transport and processing; and impact of wetting and drying cycles in C: N stoichiometry in the vadose zones of arid environments. (top)

 Constructed wetlands for NPS treatment:

    Constructed wetlands can provide an effective means for treating contaminated water. Compared to conventional treatment methods, constructed wetlands are inexpensive to build and operate and easy to maintain. Wetlands can be used to treat contaminants from sewage, strormwater, agricultural runoff, landfill leachate, and runoff from roadways. Constructed wetlands also can provide habitat for wildlife. The Nile River in Egypt suffers from severe eutrophication due to excessive nutrient loads. The objective of our research is to improve design guidelines for constructed wetlands designed to treat non point runoff from agricultural fields. (top)

 Climate Change Impacts on Water Resources:
   Water from the Missouri River Basin is used for multiple purposes. The climatic change of increased atmospheric carbon dioxide may produce dramatic water yield changes across the basin. Estimated changes in basin water yield from doubled CO₂ climate were simulated using a Regional Climate Model (RegCM) and a physically based rainfall-runoff model. RegCM output from a five-year, equilibrium climate simulation at twice present CO₂ levels was compared to a similar present-day climate run to extract monthly changes in meteorologic variables needed by the hydrologic model. These changes, simulated on a 50-km grid, were matched at a commensurate scale to the 310 subbasin in the rainfall-runoff model climate change impact analysis. The Soil and Water Assessment Tool (SWAT) rainfall-runoff model was used in this study. Overall water yield at the mouth of the Basin decreased by 10 to 20 percent during spring and summer months, but increased during fall and winter. Yields generally decreased in the southern portions of the basin but increased in the northern reaches. (top)