Projects by Discipline / Environmental Science

Aurora Reservoir Water Quality Modeling

Aurora Reservoir is a 31,650 acre-foot reservoir located in south-east Aurora, Colorado. First filled in 1990, this reservoir provides drinking water to the citizens of the City of Aurora and recreational opportunities to people in the regional area.

Water quality in the reservoir was a concern throughout the 1990's. The reservoir experiences periods of oxygen depletion in the hypolimnion. The reservoir has also had taste and odor problems, with the most severe incident occurring in 1998. In addition, the currently undeveloped 3,000 acre watershed is slated for development in the next two to ten years. The change in land use will have an impact on nutrient loading from the watershed to the reservoir.

The city wanted to predict how land use changes might affect water-quality, which required an understanding of current water-quality dynamics in the reservoir. In 1999, they retained Hydrosphere to develop a dynamic reservoir water-quality model and an associated watershed loading model. The goals of this effort were to predict the impact of various management decisions on reservoir water quality and potential treatment problems and to simulate a variety of water-quality mechanisms and constituents in the reservoir.

Hydrosphere modeled water quality in Aurora Reservoir using CE-QUAL-W2 ("W2"). W2 is a two-dimensional, hydrodynamic and water-quality model for lakes and reservoirs developed by the Corps of Engineers. W2 was used to model algae, dissolved oxygen, carbon, phosphorous, and nitrogen over a five year period. Model results were compared to observed values and simulation results closely matched observations.

Aurora Reservoir watershed nutrient loading was modeled using algorithms contained in EUTROMOD. This watershed modeling software uses a loading function approach to estimate the effect of land use activities on nutrient loading. The effect of Best Management Practices (BMPs) were identified and their effects on pollutant loading were characterized.