Mike Dunbar

After releasing water for steelhead, not enough left for trout

Ryan Cuthbert, front, a biologist with consulting firm Fishbio, and fishery technician Bob Fuller sample juvenile salmon in a rotary screw trap on the Stanislaus River near Oakdale, Calif., in April.
Ryan Cuthbert, front, a biologist with consulting firm Fishbio, and fishery technician Bob Fuller sample juvenile salmon in a rotary screw trap on the Stanislaus River near Oakdale, Calif., in April. Modesto Bee file

The equation “more water equals more fish” has been pushed as an unequivocal truth by the environmental community and their friends among government scientists for so long that it has passed from theory to dogma.

But is it correct?

“Where does that come from?” asked Doug Demko, co-owner of FishBio, which has been studying California’s rivers for 25 years. “I’m of the opinion that a lot of the government people … just don’t care” if you can prove the theory. “It comes down to wanting more water.”

Government regulators sent billions of gallons of cold water down the Stanislaus River this year to help rainbow trout swim to the ocean and become steelhead. Now, the entire trout population from Goodwin Dam to Knights Ferry is lower than at any time in the past seven years – or for as long as they’ve been studied. The population decrease is so alarming FishBio and the Oakdale and South San Joaquin irrigation districts went public with their findings this week.

To understand why this is important, you need to understand that trout need cold water to spawn; salmon need it to survive.

In a drought, like the one we’ve experienced the past four years, almost the only place to find cold water is in the deepest part of a reservoir – usually just behind the dam. The depth, volume and weight keeps the water cold even as surface water warms. Without the dam, there’s no cold water.

If you send all your cold water down the river to help a few rainbow become steelhead, you won’t have any left to help the remaining rainbows spawn. That’s what happened on the Stanislaus this year. The New Melones cold pool was purposely diminished in a futile effort – based on the more-water-equals-more-fish calculation – to push rainbows toward the ocean. Virtually none went.

“There were so few,” said Andrea Fuller, Demko’s FishBio partner, “you can’t detect a change in the number.”

Both trout and juvenile salmon “search” water for signals. A tiny fraction of trout find a cue to swim out of the rivers to the ocean where they become steelhead. All the salmon, meanwhile, eventually go. At some point, they decide to return to spawn. The nature of all those signals is an open question.

From the trout’s perspective, the releases of some 5 billion gallons of water from New Melones was wasted. It didn’t prompt any trout to leave and now it’s unavailable for the trout that need it to spawn. Instead of creating a few steelhead, we’re left with far fewer rainbows.

Meanwhile, some 12,500 salmon exited the Stanislaus in April and May this year, but only a handful, maybe 75, went with the water from the cold pool. Most took their cues from something regulators had nothing to do with – rain.

FishBio’s study, said Demko, “will support that pulse flows don’t have a significant influence on migrating Chinook salmon.”

That’s an incredibly important statement, even if it flies in the face of long-accepted dogma.

Cold-water releases and pulse flows are at the heart of “adaptive management” theory. Knowing more water equals more fish, scientists try to time releases to when they believe the fish will be leaving the rivers or returning to spawn. Often, the timing works. But FishBio’s studies show there are likely more factors at play.

What should this tell scientists? First and foremost, you can’t fool fish.

But you can fool people.

What worries us about those dogmatic beliefs is that they can be used to facilitate human agendas. If you can send water down the river to help fish, perhaps you can also pump that water – sometimes at a profit; sometimes for political purposes – to benefit farms and cities far from the reservoir where it was originally stored.

As Demko put it, perhaps it all “comes down to wanting more water.”

The State Water Resources Control Board will soon tell us how much more water it wants for the purpose of saving salmon and steelhead. It has hinted for years it will demand 40 percent of unimpaired flows on the San Joaquin River’s tributaries – double what is currently left on the Tuolumne, a third more from the Merced and up to 25 percent more for the Stanislaus. At the same time, the state is expected to release an economic impact report on what the loss of flows will mean. Our back-of-the-envelope calculations put lost ag production at roughly $540 million regionwide; totals losses could surpass $1 billion.

Perhaps coincidentally, environmental groups released a study this month showing dire conditions for some San Francisco Bay fish species. Their remedy? More water equals more fish; in this case, water from our rivers specifically.

“We want to be careful,” said Fuller, “that we don’t give people the impression that flow isn’t important – it is. But managed flow is no silver bullet.”

Without a silver bullet, we’ll need many good ideas to help our rivers. We must be willing to spend substantially more to improve habitat. The state must get serious about ridding the rivers of voracious bass. And it makes no sense to protect salmon and steelhead in our rivers then allow Bay Area fishermen to catch up to 20 percent of them in the ocean.

Fish need clean, cold water and more of it. But pouring massive amounts down the river without helping a single trout (and precious few salmon) isn’t beneficial use. We need to concentrate on finding strategies that work before putting all our faith in something that sometimes doesn’t.

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