The growth of the Las Vegas Metropolitan area may eventually lead to increased wastewater discharges into Boulder Basin of Lake Mead. In addition, Boulder Basin has experienced several algal blooms over the last few years, some of which resulted in violations of chlorophyll standards
in the spring and summer of 2001. This has raised concerns regarding the possibility of future effluent discharges exceeding the current water quality standards and total maximum daily loads (TMDLs) established for Lake Mead. Of particular concern is the current TMDL for total phosphorus (TP)
of 334 lbs/day. As a result, several alternate wastewater discharge locations and strategies are being investigated to evaluate the impacts of TP loading on water quality within Boulder Basin. Thus, studying the water quality in Boulder Basin is integral in order to assist various agencies
in making decisions on operations within Boulder Basin. Due to its extremely irregular shoreline and large surface area, Lake Mead cannot be adequately simulated by one or two-dimensional models. Therefore, ELCOM (Estuary and Lake COmputer Model), an advanced three-dimensional hydrodynamic
model coupled with CAEDYM (Computational Aquatic Ecosystem DYnamics Model) was chosen to simulate the three-dimensional transport and interactions of flow physics, biology, and chemistry in the reservoir. This paper deals with the set-up and application of the models for Boulder Basin.
Comparisons between measurements and simulation results show that ELCOM can accurately simulate the temporal and spatial variations of physical (e.g., temperature and conductivity), biological (e.g., chlorophyll-a), and chemical (e.g., nitrogen and phosphorus) parameters. This study indicates
that the hydrodynamic patterns of Boulder Basin are mainly driven by the Colorado River inflow, the Hoover Dam outflow, and meteorological parameters (especially episodes of high wind speed). However, the water quality of Boulder Basin is also affected by nutrient loading from the Las Vegas
Wash, which carries the treated wastewater effluents from municipal wastewater treatment plants, surface runoff, and groundwater discharges into the basin. The calibrated model of Boulder Basin is then utilized to evaluate various alternative discharge locations and configurations (surface
versus submerged diffuser) on water quality. In addition, an array of flow rates, lake water surface elevations, and seasonal phosphorus loadings is evaluated to identify lake management and discharge operations that are significant to meeting water quality standards and addressing TMDL limitation
for TP. The fundamental conclusion of the study is that fully three-dimensional aquatic ecosystem dynamic models can provide a very powerful tool for the accurate analysis of water body nutrient level TMDLs.
Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed. WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access.