Six summers ago, in the blistering drought of 2002, virtually all adult trout in Bear Creek were killed from the Evergreen Dam downstream at least as far as Idledale. The problem was a lethal combination of low flows, high temperatures and oxygen-robbing algae blooms. Although the community responded splendidly when watering restrictions were called, it was not enough to save the trout, and the EPA subsequently placed the creek on Colorado’s statewide list of “impaired streams.”
Today our prized local fishery has largely recovered, and the creek has been removed from the “impaired” list. The 2002 tragedy had a lasting effect on public consciousness, though, and water use overall in the Evergreen area is still 20 percent below pre-2002 levels. But in 2008, the driest and hottest year in recorded history to date, the creek and its trout are at risk again.
Thanks to decent (though still below-average) snowpack last winter, flows are still in the 20 cubic feet per second range, significantly higher than flows at this point six years ago. Fish kills started happening around 6 to 8 cfs, then became total when water stopped flowing over the dam and the creek went to “dead pool,” essentially zero flow except for sewage effluent. Evergreen Metro District officials forecast that flows should fall no lower than 15 cfs this summer, provided the usual afternoon showers show up in August. If they don’t, however, low flows could again become a deadly problem.
Of greater concern at the moment is an alarming increase in water temperatures in recent weeks, caused by a persistent high-pressure system stuck over our area. The state and EPA temperature standards for Bear Creek are a maximum weekly average of no higher than 20 degrees Celsius (about 68 Fahrenheit). Above such temperatures, trout become stressed and more vulnerable to infections. If flows drop too much further, trout may start to die from lack of dissolved oxygen — essentially suffocation.
As of last week, average weekly temperatures had soared to 19.3 C. By the time you read this, they could well have reached the 20 C mark, which regulatory agencies define as a state of “non-attainment for aquatic life forms.” Next year the state will lower acceptable temperatures to 18.3 C for rainbows and 19 C for browns, but for now 20 C remains the rule.
Evergreen Trout Unlimited has already asked its members to carry a pocket thermometer and refrain from fishing the creek as long as daytime water temperatures continue in the 70s. Even in the mid-60s, trout should be “played” no more than necessary, kept in the water until released, and never handled without wetting hands first. EMD is also helping to reduce fish stress by diverting some 2 cfs of cooler water flow from deeper in the lake to an outlet below the dam. The water district has also agreed to issue advisory watering restrictions if the high heat continues, even though its emergency plan wouldn’t normally be triggered until flows reach about half what they are now.
Bear Creek watershed residents, including private well owners and Upper Bear water rights holders, are asked to do their part by reducing outside irrigation as much as possible this month, at least until afternoon rains break the drought. Lawn grasses may brown out but will usually return. Valuable shrubs and trees can be mulched to reduce their water needs. Household water uses like dishwashing, carwashing, laundry and bathing — all of which add heat to return flows in the creek — will put less stress on the trout if done in the morning, rather than late afternoon or early evening.
According to EMD, community cooperation during the 2002 drought was phenomenal, with water use reductions of 60 percent. Even if we did only half as well this time around, it might be enough to avert another heartbreaking fish kill, and keep our treasured trout alive and well.
Hugh Gardner is the director of Friends of Bear Creek. To contribute, volunteer or learn more about Friends of Bear Creek, contact the author at 303-697-5876 or HughGardner@gmail.com.