#AnimasRiver: Sediment runoff from the #416Fire = fish kill

Screen shot of Animas River debris flow July 2018 aftermath of 416 Fire (CBS Denver).

Here’s the release from Colorado Parks and Wildlife via The Pagosa Daily Post:

Drought, hot weather… and ash and debris flows from the 416 Fire… are meeting in an unfortunate sequence of events to hit the Animas River this summer, according to Colorado Parks and Wildlife officials.

Because of the river’s low flow, the water temperature has been higher than normal and on some afternoons has risen above 70 degrees. Water temperature that high can cause fish to die. Consequently, CPW is requesting that anglers cooperate with a voluntary closure on fishing from noon to 7pm when the water temperature reaches 70 degrees.

Historical records for the river show that in mid-summer the Animas River averages 58 degrees.

“The temperature of the water does drop at night, so when the water clears we suggest fishing in the morning hours until noon,” said John Alves, senior aquatic biologist for CPW’s Southwest Region. “The fish are already stressed because of the warm water and their stress level only goes up when they start fighting a hook and line. Anglers can also go to high-elevation creeks where the water stays cool.”

Besides the water temperature, ash and debris flow increased this week; the river is running brown and fish are dying.

On July 10, after a local family reported dead fish in the river north of Durango, CPW determined that forest-fire ash flushed by heavy rain off the charred slopes killed the fish. Since then people are reporting seeing dead fish in the river from north of Durango all the way through town. The ash and debris flow came from the Hermosa Creek drainage which meets the Animas River about 10 miles north of Durango.

“We inspected the fish and found their gills were coated in ash, which caused them to suffocate,” Alves said. “In burned areas, the absence of vegetation and the presence of hydrophobic soils can lead to flash flooding and debris or ash flows even after small thunderstorms.”

The family that made the initial report collected 21 dead fish, 15 of them were brown trout. Those fish ranged in size from 16 inches to an inch or less.

Alves said that ash flows and sediment run-off are likely to continue throughout the summer as monsoon rains settle in; but some ash and sediment could continue to run off steep slopes for more than a year. The river, as of July 17, was running at about 300 cubic feet per second, compared to an average for this time of year of about 1,000 cfs.

“The water in the Animas River is so low that it can’t dilute the ash and sediment flow,” Alves said.

Trout are also stressed by all the float-craft on the river. When trout see something above they will seek cover in deep pools, behind rocks and under banks. When they’re forced to move they must use extra energy to stay safe; and because there is so little water in the river there are fewer places for fish to hide.

For anglers, CPW offers these suggestions to reduce stress on fish:

  • Buy a small thermometer and take the temperature of the water. If the temperature is 70 degrees or above, stop fishing.
  • Fish in the morning when the water temperature is cool.
  • Fish high-elevation streams which usually stay cool.
  • Use heavier tippet and land the fish quickly. Don’t “play” or tire fish.
  • Use barbless hooks which allow a quick release. Those using spinning gear – who don’t intend to keep fish – should press down the barbs of metal lures.
  • Release fish as fast as possible; minimize handling of fish and the amount of time they’re out of the water. Skip the photos for now.
  • Be sure to know the regulations for the river you’re fishing.
  • “Monsoon rains and, hopefully, snow next winter will help the river and fish recover,” Alves said. “But we can all do a little now to reduce stress on fish and on the river.”

    CPW is an enterprise agency, relying primarily on license sales, state parks fees and registration fees to support its operations, including: 41 state parks and more than 350 wildlife areas covering approximately 900,000 acres, management of fishing and hunting, wildlife watching, camping, motorized and non-motorized trails, boating and outdoor education. CPW’s work contributes approximately $6 billion in total economic impact annually throughout Colorado.

    From The Colorado Springs Gazette (Liz Forster):

    Ash and debris carried by heavy rains from the 416 fire burn scar into the Animas River north of Durango suffocated thousands of fish, Colorado Parks and Wildlife officials said.

    “We’re seeing thousands of fish struggle for their last gasp of air on the river 10 to 15 miles north of Durango, likely down into New Mexico,” said the spokesman for the Southwest Region of Colorado Parks and Wildlife Southwest, Joe Lewandowski. “We can’t even get an exact number because the river is so dark and brown, and we can’t do much about it until the runoff flushes out.”

    Lewandowski added that the Animas River has not seen such a massive die-off from wildfire debris runoff in recent memory, though the Missionary Ridge fire wiped out the fish population in the Florida River northeast of Durango in 2002.

    The hardest rains hit areas of the 54,129-acre burn scar about 5 p.m. Tuesday, the Durango Herald reported. The flooding and debris flows forced the closure of U.S. 550 and halted the Durango and Silverton Narrow Gauge Railroad train. About 400 passengers were shuttled off the train, and about 200 campers at the KOA near East Animas Road were bused to the La Plata County Fairgrounds.

    Wildlife officials and members of the public are primarily finding dead rainbow and brown trout as well as flannel mouth and bluehead suckers. The flannelmouth and bluehead suckers are of particular concern, since the two species are native and endemic to the Colorado River basin.

    “They’re very hearty fish that have endured huge runoffs, low water levels, high temperatures and a variety of other pressures,” Lewandowski said. “But we’re not sure how they’re going to do with this type of ash and debris runoff because we’ve never seen anything like this.”

    Parks and Wildlife’s first gauge on the severity of the fish kill will likely come in September.

    Biologists plan to conduct a fish survey in 6 miles of the Animas River that run through downtown Durango in which they electroshock the fish and record their numbers, weight, size, species and other observations.

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