From the Aurora Sentinel (Brandon Johannson):
…because of an agreement between the two water departments, state wildlife officials say the future of the rainbow trout population in that stretch of the South Platte — one of only two natural rainbow fisheries on the river — is much brighter than it was a few years ago.
Under the agreement between Parks and Wildlife, Aurora Water and Denver Water, the three agencies are working together to make sure stream flows in the Platte remain constant during the critical spring spawning season.
Regulating the flows in the canyon required Aurora’s and Denver’s help because flows there are largely determined by the water departments’ decisions upstream. Denver Water owns Eleven Mile Reservoir, which flows into the Platte, and Aurora owns Spinney Mountain Reservoir, which feeds Eleven Mile. Because it is a designated “drought reservoir,” the output from Eleven Mile into the Platte is based on what Aurora dumps from Spinney. If Aurora dumps too much, the Platte moves too fast and the young trout are rushed downstream just as they emerge from the egg. If the water level drops too quickly, fertilized eggs could be exposed and dry up on the banks…With a pile of numbers in hand, Spohn approached Aurora and Denver and asked them to maintain a steady flow during some crucial times. If the river could stay at about 75 cubic feet per second, it would be ideal for spawning, he said. But job No. 1 for Aurora Water and Denver Water is making sure when someone turns on their tap or their sprinkler, a steady stream comes pouring out — regardless of what that means for trout in the canyon. Sometimes that means more than 75 CFS, often as much as 200 CFS. “We can’t operate to the detriment of the citizens of Aurora,” said Brian Fitzpatrick, water resources manager for Aurora Water…
And while Spohn’s focus is on improving the trout fishery in Eleven Mile Canyon, he knows that’s not Aurora’s chief concern. “Wildlife understands that Aurora’s job is to provide water to their customers in the city,” he said. That’s where Denver Water comes in. When Aurora slows the flow from Spinney — often to levels well below what the city needs — Denver Water steps in and loans Aurora some water from Strontia Springs Reservoir. As soon as flows can be bumped up again, Aurora pays back Denver with water from other storage.