Cherry Creek Reservoir is a flood control reservoir that has had periodic blue-green algae blooms and high chlorophyll α concentrations.
To increase oxygen at the bottom of the reservoir and reduce the amount of internal nutrient loading, a destratification system was installed in the reservoir in 2008. The system was also intended to help control cyanobacteria in the reservoir by disrupting their buoyancy. However the destratification system has not achieved these goals. Additionally, there has not been enough evidence to show how the destratification system may influence cyanobacteria blooms.
Due to continued water quality concerns, a water quality model of the reservoir was developed to:
- Better understand the causes of chlorophyll α standard exceedances and cyanobacteria blooms;
- Determine the impacts of the destratification system;
- Provide a tool to help predict the effects of future management strategies.
The Authority chose a two-dimensional hydrodynamic and water quality model of the Cherry Creek Reservoir that simulated in-reservoir water quality for 2003-2013.
In 2018, the Authority approved the development of a Bubble Plume Model to occur concurrently with a Destratification System Study, and an update to the Reservoir Model through 2017. This work is currently in process, and will continue into 2019.
The current version of the Cherry Creek Reservoir Water-Quality Model was developed using CE-QUAL-W2, version 3.71. The model accounts for artificial mixing in a simplified manner, in that mixing by the destratification system is simulated as a multiplier on vertical mixing in the depth interval above the diffusers. Bubble plume dynamics are not directly simulated. The Authority is interested in simulating in-reservoir responses due to the effects of destratification by accounting for bubble plume dynamics. A bubble plume model will be used with the CE-QUAL-W2 model to mechanistically simulate the effects of the destratification system on mixing in Cherry Creek Reservoir. This will allow for a more realistic representation of the destratification system in the Cherry Creek Reservoir Water-Quality Model than currently exists, which would then allow the model to be used for evaluating proposed modifications to the existing system and operations.