The 263 dead fish found scattered on the banks of Boulder Creek last month were killed by a combination of high temperatures and low water flows.
Sections of Boulder Creek were just a trickle on Aug. 20 — with water flowing by the Millennium Harvest House at only 1 cubic foot per second — because of high demand by area water uses. And the high temps pulled the oxygen out of the streamflow that was left.
From today’s Daily Camera:
Carol Ellinghouse, water resources coordinator for the city of Boulder, said a natural — but dramatic — decrease of about 20 cfs was measured in Boulder Creek’s flow at Boulder Falls on Aug. 20.
She called the drop an unusual “natural phenomenon” but couldn’t say specifically what might have caused it. Officials traveled upstream of Barker Dam in Nederland to see if there had been any illegal diversions of water but found none, she said.
Ellinghouse said the state water commissioner for Boulder Creek, who controls how much water is diverted by rights holders along the waterway, was unable to react quickly enough to the sudden drop in stream flow Aug. 20 to prevent the fish kill.
“It was a very dramatic drop,” she said. “He assumed there was a larger influx of water into the river.”
The city of Denver wants to build a bigger dam in southern Boulder County, nearly tripling the size of its reservoir.
And environmentalists have something to say about it: They want to know if Denver would mind making that dam even a little bit bigger.
It’s an odd request from a group like Trout Unlimited, which has partnered with the cities of Boulder and Lafayette to try and negotiate the bigger dam, but it actually represents a calculated effort to make the best out of a bad situation.
Denver — thirstier now than ever – is trying to push through a plan to expand Gross Reservoir by 72,000 acre feet, which would require making the current dam 125 feet taller. The water to fill the new reservoir would be pumped from the other side of the continental divide, sucking more water out of the tributaries that feed the now-not-so-mighty Colorado River.
The Colorado office of Trout Unlimited, based in Boulder, thinks this is a terrible idea, but they’ve come to accept the reality — there may be no stopping the project. But there may still be an opportunity for a small victory to be had in the Gross Reservoir expansion.
Environmentalists are asking Denver to consider adding an extra 5,000 acre feet of water to the reservoir, creating a bank of water that could be used to guarantee that South Boulder Creek, which flows from the dam at Gross Reservoir through the stunning cliffs in Eldorado Canyon State Park.
Most winters, South Boulder Creek completely dries up as Denver draws down the water in the reservoir, causing devastating fish kills and compromising the stream’s ecological integrity.