Unseasonably hot weather, coupled with little or no rain since mid-August, decreased the flow of water out of Pueblo Reservoir to less than 100 cubic feet per second (cfs) for several hours on Wed., Sept. 22. The drop in outflow resulted in less than 50 cfs going into the main channel of the river, and only 31 cfs flowing through the Pueblo Hatchery.

"The flow out of Pueblo Dam dropped because of low inflows into the reservoir combined with a reduction in water demand for downstream irrigation," explained Grady McNeil, the Resource Support Manager for the DOW. The river could have remained dangerously low for an extended period if additional releases had not occurred, he added.

The dramatic drop in flows also threatened an important urban fishery below the dam. "We stood to lose tens of thousands of fish in both the river and the hatchery," said Doug Krieger, the DOW senior aquatic biologist for the region. "These conditions jeopardized a true, high-quality urban fishery that is an essential winter destination for Front Range trout enthusiasts."

In an effort to save the fish, Colorado State Parks offered to adjust their water flows to John Martin Reservoir. That gave the DOW time to make an emergency purchase of 1,000 acre-feet of water from Colorado Springs Utilities. The Parks and Wildlife water is being released incrementally until Oct. 4, when Catlin Canal Company is scheduled to begin moving water out of Pueblo Reservoir.

The Catlin release should bring the flow up to 200 cfs.

The 45-year historic average is between 300 - 400 cfs at this time of year.

"We are extremely thankful to Colorado Springs Utilities to lease some of their water to us and to Parks for evenly distributing their flows," said McNeil. "Ordinarily, Parks would release water at as high a rate as possible to reduce transit losses. Given the low flow problems for the fishery below the dam, they agreed to release their water at a lower rate."

Water coming out of Pueblo Reservoir is split as soon as it comes out. Some of it flows through the Pueblo hatchery, and the rest of it goes into the river. The hatchery water then flows back into the river about three-quarters of a mile below the dam.

"Both flows are critical for fish," said Krieger. "The water going through the hatchery flows through raceways where young trout are raised. And the water going through the first three-quarters of a mile of the Arkansas supports one of the finest urban trout fishing rivers in the state. Without a constant supply of fresh water, tens of thousands of fish would be threatened."

Water management on the lower Arkansas is very complex due to the number of water interests involved including agricultural interests, the Colorado Divisions of Water Resources, Parks and Wildlife, the Southeastern Colorado Water Conservancy District, the Bureau of Reclamation and Front Range municipalities such as Pueblo, Colorado Springs and Aurora.

"Maintaining adequate flows in this stretch of river benefits the river, the fishery, recreation and aesthetics," said Dan Prenzlow, SE Region Manager for the DOW. "Three separate cooperative flow agreements are currently in place, although none of them ensured adequate flows in this case. This isn't the first time we've faced this situation, and I think it is important that we get everyone together to try to find a cooperative solution to prevent this in the future."

The sudden drop in water prompted Pueblo hatchery managers to stock a large number of trout ahead of schedule. "We cut flows through the hatchery, which allowed a higher release into the main river," said hatchery manager David Harris. "But that meant we had to reduce the number of fish we were holding, so we stocked out several raceways of fish that were destined to be stocked later this year. These fish were not quite to catchable size yet, but were close enough due to the nature of the circumstances."

Harris said the early releases will not significantly impact this year's or next year's stocking.

News Source: Colorado DOW - Sep. 25, 2010