Water that was too warm killed about 5,400 rainbow trout — nearly all of them — at the Whatcom Falls Park hatchery during a summer marked by drought and high temperatures.
Most of the fish were in two large shallow ponds at the hatchery, which belongs to the Washington state Department of Fish & Wildlife but is operated by Bellingham Technical College’s fisheries program.
“This weather we’ve had, we’re seeing warmer water temperatures than we’ve ever seen historically,” said Kevin B. Clark, Nooksack Basin hatchery manager for Fish & Wildlife. “It basically cooked them.”
Clark said the massive fish die-off occurred first in one pond, around mid-July, and then in a second pond the third week of July — both seemingly overnight.
“This is an absolute first for us. I hope it’s not a pattern,” he said, noting the dead fish were “warm to the touch.”
This was the second hottest July on record in Bellingham. The average high was 76.8 degrees, according to the National Weather Service. The normal high is 71.3 degrees.
The average low was 57.7 degrees, well above the norm of 53.5.
Water temperatures at the hatchery were, on average, four to five degrees warmer than usual for that time of the year, with a high of 76.2 degrees that was recorded shortly after a hot Fourth of July weekend, according to Clark.
“That’s so warm you just look at them and they just about die. The fish just don’t like water that warm,” said Earl Steele, fisheries instructor at Bellingham Technical College.
BTC’s fisheries program and its students operate the hatchery for the state.
Clark said most of the fish that died were going to be among those put into lakes in Whatcom, Skagit and Island counties for fishing. A couple hundred managed to survive.
“I hope they can make it until things cool off,” Clark said.
Of those that died, he said, “That’s over a year’s worth of work for us.”
The water for the hatchery ponds at Whatcom Falls Park is pulled from the shallowest part of Lake Whatcom, near Bloedel Donovan Park, and then a gravity-feed system empties water into the ponds.
The water is cooler when it first drops into the concrete ponds.
When temperatures started to climb, the hatchery tried to cool the ponds by exchanging the water faster and putting a tarp over one of the ponds. Neither could offset the warmer temperatures.
Clark said people asked him why crews didn’t truck the fish to places with cooler temperatures. He said with the amount of stress the fish experienced because of the warm water, they likely would’ve die as he tried to transport them.
And Bellingham water couldn’t be used to cool the ponds because it contains chlorine, which is deadly to fish.
“We get a lot of visitors to Whatcom Falls Park,” he said, “and there was a lot of questions.”
This might have been the last year for visitors to see fish at the hatchery during summer.
Warmer temperatures in recent years already required crews to treat the trout for columnaris and “ich,” bacteria and parasites that sicken fish. That’s made it more difficult to have fish at the hatchery during summer the past three years.
In the short term, the state will continue to use the hatchery at Whatcom Falls Park, but only until the second week of April when the fish will be put into area lakes for the opening of trout fishing season.