OGALLALA -- A major fish dieoff that occurred recently at an Imperial area impoundment has sparked concerns for other Southwest Nebraska water resources and the fisheries they support.
In December, the entire fishery in the Light Dam Reservoir, southwest of Imperial was lost due to low water after the Frenchman Creek, which feeds the impoundment, dried up.
More than 400 dead game fish were discovered there in December, following a year of near zero flows in Frenchman Creek in that area, and according to Nebraska Game and Parks Fisheries Supervisor, Darrol Eichner of Ogallala, other significant fish kills in the area have occurred and are likely to continue as a result of groundwater depletion.
Eichner said that a major die off occurred at Swanson Reservoir in Hitchcock County in 2000, where more than 35,000 fish perished as a result of low water and high temperatures. He said that Enders Reservoir, located on Frenchman Creek is at near record low water levels, and that Hugh Butler Reservoir on Red Willow Creek also dipped to record lows last summer.
The yearly annual inflow trend from Red Willow Creek indicates a downward slope. The yearly historic flow of Medicine Creek above Harry Strunk Reservoir also shows a linear downward trend.
He said that ultimately this is having a dramatic affect on Harlan County Reservoir, which receives water from the Republican River and its tributaries including Frenchman and Medicine Creeks.
Eichner said that in every case of low reservoir pools, the trend has been an annual depletion in flows upstream from the reservoir. He said that unlike Platte River Reservoirs, none of the southwest reservoirs derive their water from runoff snowmelt in the Rocky Mountains. Instead, he said. Frenchman Creek Red Willow Creek and Medicine Creek are what the USGS identifies as baseflow-dominated streams. Base flow- dominated streams are streams that get most of their flow from groundwater.
Eichner said that stream flow depletions of Frenchman Creek are directly correlated to extensive center pivot development in southwest counties, and that precipitation trends have insignificant impacts on Enders Reservoir inflow. He pointed to Frenchman Creek as an example.
Frenchman Creek historically began its flow in northeastern Colorado. Last year, a trickle of water began to seep from the ground just four miles upstream from Enders Reservoir amounting to only about a 4,900 acre feet deposit of water in the reservoir last year. Prior to the 1970s when irrigation development began in that area, a yearly average of about 60 000 acre feet resulted from inflows from Frenchman Creek into Enders.
Rainfall doesn't seem to have much impact either. The yearly precipitation trend has an upward slope over the past half century, but stream flows continue to decline. Recent readings indicate only four cubic feet of water per second flow into Enders Reservoir," Eichner said.
He said that although Enders and Hugh Butler Reservoirs have not experienced fish kills in recent years, they were victims of blue-green algae blooms and subsequent public health advisories.
Of great concern in the southwest is the health of the Rock Creek Fish Hatchery, a Game and Parks facility on Rock Creek in Dundy County. Rock Creek Hatchery Superintendent Hal Walker said that the hatchery was built in 1924 because springs provided an abundant supply of cold clear water for use in hatching trout eggs and rearing fingerling and catchable size trout for distribution to public waters statewide, including Lake Ogallala. Walker said that Lake Ogallala is considered to be the state's premier trout fishery, and the Rock Creek Hatchery has been stocking the lake for more than 60 years.
Walker said that the continued decline in the flow of springs and the stream threatens the existence of the hatchery.
The flows have declined nearly 20 percent since 1997 and 42 percent since 1971, dropping to 4.7 cubic feet per second in 2004. In 2003, the Game and Parks Commission completed a renovation of Rock Creek Lake, located south of the hatchery. The final investment in this project totaled $609,927.41. Rock Creek Lake draws fishermen from Nebraska, Colorado and Kansas and is important to the local economy.
Walker said that other creeks in the southwest have been adversely affected.
"Many creeks in this area were trout supporting, including Buffalo Creek, and the Arikaree as well as the upper Republican River. That's not the case any longer," Walker said.
Eichner said that declining inflows into area reservoirs and lakes are a serious concern.
"All four Bureau of Reclamation Reservoirs in southwest Nebraska have been experiencing varying amounts of declining inflows for the past 35 years. Most critical are the inflows from the Frenchman Creek into Enders Reservoir" Eichner said.
According to a recent report filed by the Bureau of Reclamation, "... due to extensive groundwater pumping above the reservoir (Enders), the inflow (2003) was only 10 percent of the average historical preconstruction flow at the Enders Dam site."
Eichner said that in 2004, the Frenchman flow dropped to 8 percent of its historical output.
Eichner feels that the threat of losing area outdoor water-based recreational opportunities is real, and this loss would have far reaching economic impacts of its own.
"Many people choose to live in an area if certain amenities like hunting, fishing, boating and camping opportunities exist within a reasonable distance from their home," Eichner said.
He said that state economists agree that the lack of a diversified economy is the reason that many of Nebraska's rural counties are experiencing declining populations, and he feels that the loss of outdoor recreational amenities could accelerate those population declines.