Colorado Parks and Wildlife has confirmed a “large-scale fish kill” along the Rio Grande below Del Norte that was the result of a 7.2-mile stretch of the river being dried up as part of a river restoration project.
The Rio Grande Headwaters Restoration Project has its Farmers Union Canal Diversion and Headgate Improvement project underway in the area. During construction on this project a decision was made that caused the ecological disaster.
On Monday, a team of nine CPW staff walked stretches of the river channel and collected as many fish as they could, said John Livingston, southwest region public information officer for CPW.
“There were too many dead fish for the team to collect them all,” Livingston said in an email exchange with Alamosa Citizen.
The state agency was notified by a landowner on Feb. 3 that the north branch of the Rio Grande east of Del Norte was being dewatered, and fish were dying or dead.
Through its investigation, CPW determined that the species impacted include sportfish such as brown trout and rainbow trout, brook stickleback, longnose dace, fathead minnow and white sucker. Additional species such as northern leopard frogs and aquatic invertebrates such as mayflies, caddisflies and stoneflies, among others have also been found dead, according to Livingston.
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“A significant number of the fish populations in that stretch died across all age classes. Brown and rainbow trout as small as two inches and up to 24 inches have been found, along with all sizes in between,” he said.
Brown trout spawn in the fall and this year’s eggs that were laid in the rocky bottoms of the river most likely have been lost, CPW reported.
“CPW faces challenging conditions to determine how many fish perished from the rapid dewatering. Many dead fish have also been scavenged by birds, raccoons, skunks, and foxes flocking to the area and others have been isolated in frozen pools,” Livingston said.
The Farmers Union Canal diversion project received nearly $1.3 million in funding through the U.S. Bureau of Reclamation. The Rio Grande Restoration Project and San Luis Valley Irrigation District are teaming up on the project.
Farmers familiar with the project told Alamosa Citizen a “hasty decision” was made to move ahead on the project during a cold spell this winter, resulting in the drying of the river through private corridors of the Rio Grande.
“There’s a lot happening behind the scenes to remedy this. Landowners are pissed,” one rancher told the Citizen.
CPW is concerned about the fish kill and potential impacts to other species, such as amphibians and aquatic invertebrates, and the potential impacts to the riparian corridor. An aboriginal population of Rio Grande chub, a Tier 1 Species of Greatest Conservation Need, has been documented in this reach of the Rio Grande, according to state parks and wildlife.
“This stretch of river is habitat for the federally endangered southwestern willow flycatcher and the federally threatened western yellow-billed cuckoo. While flycatchers and cuckoos do not overwinter in this reach, they rely on this habitat for nesting and rearing their young every spring and summer,” said Livingston.
Credit: CPW
Aquatic biologists estimate it could take three to five years to recover the fishery, he said.
“CPW wants to thank the landowners along the river for their cooperation and for providing access to the river for this investigation, and CPW shares their concerns regarding this incident,” Livingston said.
Alamosa Citizen is seeking comment on this from Daniel Boyes, executive director of the Rio Grande Restoration Project.
Here’s more on the project itself.