Fish survival in question in some shrinking area agricultural reservoirs | CraigDailyPress.com
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Fish survival in question in some shrinking area agricultural reservoirs

 

Steve Wyant releases a brown trout he caught in the Yampa River in March just below Stagecoach Reservoir. (Photo by Dylan Anderson)

With multiple area agricultural reservoirs at extreme lows and some predicted to drop to only streams running through reservoir basins by fall, some fish populations could be threatened during this time of drought.

“If reservoir levels get very low, fish survival may come into question, and fish loss could occur,” said Colorado Parks and Wildlife aquatic biologist Bill Atkinson.

Fish in agricultural reservoirs may escape downstream through outlets as water levels drop, and fish may survive in lower-level waters remaining in reservoirs, Atkinson said.



If water conditions improve next year, CPW can quickly reestablish fish populations from fingerlings or small fish raised in hatcheries in Yampa, Rifle or Glenwood Springs, Atkinson said, adding CPW plans fish stocking schedules two years in advance.

CPW employees tackle tricky fish work such as netting pike out of Casey’s Pond each spring and performing fish counts on the Yampa River, but taking fish out of shrinking reservoirs is not really an option, Atkinson said. The mucky reservoir bottoms are not easily navigated.



“Fish salvage is very complicated,” he said. “You can be up to your knees in mud. Logistically it’s not that easy. Fish salvage from drawn-down reservoirs and lakes can be difficult and unsafe.”

Even if fish can be rescued, it is risky to attempt to transplant fish.

“Transportation of fish from one water body to another has potential risks such as transporting disease pathogens. There are strict regulations about moving fish,” said Atkinson, who has worked in the CPW aquatics section for 22 years.

Other lakes may not have the capacity to handle more fish, and CPW fish hatcheries have very limited isolation unit space that is reserved for conservation of unique fish populations and preserving native cutthroat trout, Atkinson said.

At the 128-acre, agricultural Stillwater Reservoir west of the town of Yampa, the reservoir capacity is at 11% this week, or only 700-acre-feet. But the outlet does not have a fish screen, so fish may pass through to Bear River as the water level lowers. If that happens, fishing below Stillwater and in Bear Lake downstream could be good later this summer, Atkinson said.

Stillwater is usually stocked with small cutthroat trout raised at the fish hatchery in Glenwood Springs, but Atkinson said no new fish were stocked at Stillwater this year due to the lower fill level.

CPW staff worked diligently during this drought year to protect fish as much as possible by monitoring populations as well as river and reservoir levels to alter stocking plans and educate anglers.

Atkinson said he plans to evaluate at Stillwater again this weekend to make population management decisions, which can include temporarily removing fish bag limits to encourage more anglers to fish the lower-level waters.

“In situations where fish populations could be threatened due to extremely low water levels, CPW implements a management action such as removing bag limits to allow anglers to harvest more fish,” Atkinson said.

In Yamcolo Reservoir downstream on the Bear River, the reservoir is currently at 24% capacity. Some anglers are finding safe places to fish from rocky areas to the muddy shoreline of the low reservoir. CPW did stock fish at 175-acre Yamcolo earlier this year since the reservoir maintains a base of water including municipal water rights and a deadpool. Yet, fish concentrated in less water may compete for resources.

“Growth rates of fish may be hampered during water levels with a lower carrying capacity,” Atkinson explained.

Sheriff Reservoir northwest of Yampa, owned by the town of Oak Creek, currently is being gradually reduced in water levels due to upcoming grant-funded maintenance work. That reservoir should be lowered to 40% capacity by Oct. 1, town officials said.

At 78-acre Gardner Park Reservoir, located east of Yamcolo, the water only filled to two-thirds of capacity this year, and the shallow agricultural reservoir may drain to only a stream running through by fall, said Yampa resident Andi Schaffner, a reservoir water rights owner. So CPW only stocked a limited number of fish at Gardner Park this year, and Atkinson said bag limits also will be reviewed.

Other fish stocking this drought year was diverted from agricultural reservoirs to larger recreation-based lakes such as Steamboat Lake, which does not vary as much in water levels, Atkinson said.

This year, CPW officials encouraged river anglers to explore high country lakes. Atkinson said he continues to witness abnormally high afternoon water temperatures in the 70s in the Yampa River through Steamboat, which is closed for fishing and recreation. With the warm water temperatures, higher ambient air temperatures and lower river water levels, fish in local rivers are stressed.

Fish in larger lakes avoid the heat too, so anglers will have more luck fishing earlier and later during the cooler parts of the day or in deeper waters this time of year, Atkinson said.

“During July and August, typically the fish will occupy habitat in deeper waters such as 15 to 20 feet deep in Steamboat and Stagecoach,” Atkinson said.


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