Strontia Springs Reservoir started spilling on May 2. Between 1,200 and 1,700 cubic feet per second has been flowing out of the spillway since that time.
We’re off to see the wizard, the Water Wizard of Oz
Pulling back the curtain on how we move Denver’s water
By Travis Thompson
In middle school, I wrote a paper on the symbolism of “The Wizard of Oz.” Dorothy represented American values, the Tin Man was a metaphor for industrial workers and Oz signified the American dream.
Today, I think of that classic film in more local terms. Colorado, with all its beauty and majesty, is the wonderful Land of Oz, threatened only by our own Wicked Witch of the West: drought.
We all know it takes a bucket of water to stop the witch, but those buckets aren’t filled and poured without some helping hands. Enter the man behind the curtain, or in this case, the men and women who serve as Denver Water’s supply managers.
Led by Bob Steger, manager of raw water supply, the team analyzes conditions and projections to strategically position water throughout our system.
Because Denver Water’s reservoirs are connected by rivers, canals and pipes, our water managers are able to strategically move water throughout the system every day. Their efforts ensure that the water supply is appropriately distributed among our reservoirs or released into the river to benefit aquatic habitats.
So, let’s pull back the curtain to see how the water managers handled May’s heavy rains.
Currently, Cheesman and Strontia Springs reservoirs have water flowing over their spillways — an area on each dam designed to release water back into the river when it is full. The connotation of spilling may lead some to believe that these reservoirs are flooding. But, that’s not the case.
Our water management team is using the spillway instead of the large valves in the dam that are typically used to release water from a reservoir back into the river below.
It’s not abnormal for Cheesman Reservoir to spill, but it doesn’t happen every year. Before 2014, the last time the reservoir spilled was 2009.
Why? Because operating the valves in a dam requires a lot of work from the Denver Water caretakers stationed at our reservoirs. Morning or night, in good weather and bad, each time the water levels in a reservoir need to be adjusted, these employees have to go inside the dam and electronically or manually turn oversized valves the size of a wheel on a semi-truck until the precise flow is released.
With runoff season underway, above-average reservoir levels and rainstorms delaying the start of watering season, Steger said spilling is a good option right now — especially considering the impact on the employees having to manually regulate the valves.
The duration that each reservoir will spill depends on conditions and variables calculated by the team. In addition to weather, this year our supply managers will be monitoring the Antero Dam construction project and water temperature.
In June, Denver Water will drain Antero Reservoir to clear the way for significant repairs to the dam. That may cause Cheesman Reservoir to spill most of the summer, as managers send the Antero water back into the South Platte River, feeding other reservoirs within our system downstream. (Read Draining Antero Reservoir: Where will all that water go? to learn more about rehabbing a 100-year-old dam.)
But it isn’t necessarily that simple. Our water managers also have to keep an eye on river temperature, which can affect aquatic life. If the water temperature below the dam gets too warm, they will send more water through the valves to cool the river and maintain a healthy fish habitat downstream.
It’s hardly wizardry, Steger says, though on some days it may feel that way.
“Whether we are experiencing drought years or wet years, we have to make sure the water we have available is in the right spot at the right time,” he said.