Testing COE-CE-QUAL-W2 Reservoir Water Quality Model Algal Grouping Code
Reclamation, Tennessee Valley Authority (TVA), and the U.S. Army Corps of Engineers (Corps) have had a joint research coordination team building, testing, and using reservoir water quality models. The COE-CE-QUAL-W2 model has become the standard. Upper Colorado (UC) Region has been the most active in using W2 in Reclamation. The latest version (3.x) has a test compartment to predict 6 major algal groups. The purpose of this project is to test the algal compartment in Deer Creek Reservoir to see if it can be calibrated to western reservoirs.
Need and Benefit
Since the types of algae can impact drinking water treatability, the bad algae can have significant impacts on drinking water supplies. Filter plugging algae can reduce the quantity of water that can be treated by more than 50 percent. Noxious blue-green algae can produce both taste and odor problems, plus they can produce toxins, all of which are difficult and expensive to treat. Deer Creek Reservoir has a 20-year history of implementation of a watershed phosphorus wasteload allocation program, which has nearly eliminated massive blue-green algal blooms.
Reclamation built and operates Jordanelle Dam upstream of Deer Creek Reservoir. The operation of a selective level outlet works (SLOW) on Jordanelle Dam is a major component of water quality improvement downstream in Deer Creek Reservoir. Deer Creek Reservoir has undergone major changes in algal population and total biomass dynamics over the past decade. Over 40 thousand Total Maximum Daily Loads (TMDLs) are being developed nationwide (similar to the Deer Creek phosphorus watershed wasteload allocation). Many involve expectation of measurement end-points in reservoirs, but the actual reservoir assessment tools have not been used to accurately predict if the watershed treatments will produce the desired results.
One of the important needs in further developing CE-QUAL-W2 is to test and/or modify the reservoir sediment headcutting and phosphorus diagensis components of the model and to test the algal compartment prediction capabilities which have recently been added. Although the six-group algal compartment code has been added to the model, almost no significant testing has been completed to determine how to--or even if--the model can be calibrated across a number of applications. Certainly no reservoirs have been tested for multiple years with a significant phosphorus and algal population reductions or group changes. Western United States reservoirs need a separate verification from southEastern United States reservoirs.
The residential development around western reservoirs and conversion of irrigation water supplies to municipal and industrial (M&I) supplies is modifying Reclamation's mission across the Western United States. A better understanding of how TMDLs and Reclamation's operation of reservoir/river/reservoir sequences is crucial to future optimization of the Western United States limited water resources. Being able to model these reservoirs to predict water quality impacts of both operational changes and of watershed treatments (e.g., TMDLs) is a critical component of future water resources management in the Western United States.
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