The west fork of the Amon Wasteway has three strikes against it that make it poor habitat for juvenile salmon and trout, the Kennewick Irrigation District board learned recently.
The waterway near Badger Canyon and through the Meadow Springs Country Club gets too hot in the summer, has too much silt and doesn’t have enough fast-moving water for those fish, biologist Ian Courter told the KID board at a meeting last week.
Courter and David Child, a consulting biologist for the Yakima Basin Joint Board, recently finished a study of the west fork to answer questions about the wasteway’s current habitat.
There has been debate in recent years about the Amon Wasteway. KID clearly sees it as irrigation water since the wasteway didn’t exist before KID first turned on its canal system to bring Yakima River water to area farmers in 1957.
But the state Department of Fish and Wildlife claims the wasteway is state water under its jurisdiction.
Some considered the wasteway an urban creek during the 2000s, said Seth Defoe, KID’s planning manager. There was an interest expressed in having the irrigation district add fish passage where the wasteway goes through the country club to open up the west fork to salmon and trout.
But while there was plenty of anecdotal information, there hadn’t been a scientific study that really examined what sort of habitat the wasteway offered to juvenile salmon and trout, Defoe said.
After an initial study, the Department of Fish and Wildlife suggested a closer look that the west fork because it seemed to have cooler water temperatures than the main stem of the wasteway, Defoe said. The most recent study, which was funded by the Yakima Basin Joint Board, focused on that.
The west branch of the wasteway, which also has been called Amon Creek and East Badger Drain, drains irrigation spill and return flows from east Badger Canyon, travels through the preserve, and joins with the main, east branch of the wasteway inside the country club then returns to the Yakima River.
Water temperatures in the west fork are too warm to support salmon and trout, which are cold water fish, Courter said.
And the west fork mostly has fine sediment, which is poor habitat, he said. Juvenile salmon and trout prefer to have gravels and cobbles because that provides places for aquatic insects to breed.
“If you have no cobbles and boulders, the fish have nowhere to hide,” Courter said.
The west fork also lacks riffle habitat, which is an area with higher velocity water where aquatic insects are kicked up and suspended in water, Courter said. That’s how juvenile salmon and trout find the bugs to eat.
Researchers found only a few trout or salmon around the golf course and none in the rest of the west fork of the wasteway, he said. That made sense based on the habitat conditions.
Some cooler temperatures were seen in the upper part of the west fork where irrigation water seeps into ponds, Child said. There is a population of mosquito fish in that area, but those fish were introduced by the Benton County Mosquito Control District.
Now when KID needs to make decisions about how to manage the wasteway, there will be scientific data available to inform those decisions, Defoe said.
The amount of water in the wasteway is going to decline as the irrigation district continues conservation projects. And KID officials may consider options of how to capture and reuse the irrigation seepage and spill water, since it has a right to the water.