Repairing a set of fish ladders in Upper Bidwell Park could increase salmon runs substantially
Seeing is believing, as they say. That’s why Jim Walker, a member of the city’s Bidwell Park and Playground Commission, recently braved rattlesnakes and poison oak to visit a site on Big Chico Creek in Upper Bidwell Park.
His goal was to find out whether the old fish ladders in the Iron Canyon section of the creek, above Salmon Hole, could be repaired without doing excessive damage to the creek and park. Over the years since they were constructed in 1958, the ladders have become damaged to such an extent that salmon have a harder time getting upstream, especially in low-flow years.
Repairing the ladders, which extend over approximately one-quarter mile of the creek, would allow more migrating salmon to reach breeding grounds farther upstream, thereby enhancing the annual salmon runs. This would be especially valuable for the spring run of the fish, which has declined sufficiently to be placed on the California Endangered Species Act list.
The biggest problem with the site is that it’s not directly accessible. The canyon is extremely steep at this site, and there is no way to get to it from the bluffs immediately above. It can be reached only by walking upstream from Salmon Hole.
As a result, Walker knew, a huge crane would be needed to get materials to the site. Walker wanted to see if the crane could be brought up Upper Park Road and onto the staging area near Parking Lot O without damaging the park. If so, another obstacle in the way of the restoration project would be removed.
Joining him on the excursion were Susan Strachan, executive director of the Big Chico Creek Watershed Alliance, and Sam Plank, an engineer with HDR Engineering, who brought a measuring tape.
Last month, Walker and his fellow commission members reviewed plans for repairing the fish ladder in Iron Canyon. At the time Walker expressed concern about the possible damage the crane could do to roadside trees as well as damage reconstruction might do to the canyon itself.
This was a quandary, because it seemed to pit two environmental issues against each other: saving the salmon versus protecting the park. The Fish & Wildlife Service is eager to make the repairs as part of its Anadromous Fish Restoration Program and to pay for them, but it won’t move forward without the city’s approval.
Walker’s visit to Iron Canyon convinced him that was an illusionary conflict. The crane could be brought in without trouble, he realized, and he feels confident that the reconstruction work can be done with minimal impact on the creek.
“I had some concerns about how the construction would be done,” he explained. “But these are water-loving, fish-loving people [doing the work], and I feel they probably have the best long-term interests in mind.”
Strachan agrees: “I don’t think there’s a conflict between the park and the fish. I think that the fish are a part of the park.”
The new ladder will replace the one already in place, which Strachan said works only in high-flow years. During low- and medium-flow years, it won’t let fish through to spawn farther upstream. Instead they remain trapped in Salmon Hole (thus the name), where the water becomes too warm, swimmers intrude on them and they cannot spawn.
According to a salmon count Strachan provided, last year the river had 299 salmon during a higher flow compared with 67 in 2005 and zero in 2004. The goal with the new ladder is for 800 salmon annually to get at least as far upstream as Higgins Hole, the uppermost pool. It has cooler water than the lower pools and is bordered by private property, so people are far less likely to disturb the salmon during their hibernation-like summertime state.
Salmon counts are done using snorkels; the counters start in Higgins Hole and swim or walk down the river, counting the fish as they go.
In years past, there have been attempts to help the salmon along, including flying them from Salmon Hole to Higgins Hole. Strachan said that she didn’t remember it working very well. “I don’t think that the fish were too excited about taking a flight,” she said.
The ladders themselves will be a series of steps, or “weirs,” concrete pools designed to attract salmon with a strong current coming out of a notch.
To meet the concerns about possible damage to the canyon walls, the ladder’s design has been changed several times. Notably, the new plan does not call for using dynamite to clear the canyon walls. Earlier versions had called for explosives to prevent rocks from falling on the new steps of the ladder.
Also, the ladders will have fewer steps, a change that will reduce the amount of construction required. The fish will have to jump slightly higher than is optimal, a foot and a half instead of a foot, but they can do it, Strachan said.
The many changes over time have caused some confusion, said Susan Mason, of Friends of Bidwell Park. “It’s hard to keep people focused on the current plan. At the park commission meeting people asked about things that have changed.”
Mason mentioned the success of salmon restoration efforts in Butte Creek and said she hoped that such success could be duplicated in Big Chico Creek. Chief among the Butte Creek improvements was construction of ladders around the Durham Mutual Diversion Dam in 2005; the new ladders, along with many other improvements, have provided passage to thousands of salmon, according to the Fish & Wildlife Service’s Anadromous Fish Restoration Program Web site.
The Iron Canyon ladders project is moving forward. The first of three phases, initial evaluation, has been completed. An environmental-impact report must be written and final engineering designs completed, followed by construction. It’s expected to cost somewhere between $1.5 million and $1.75 million.
If the City Council approves the project and funding becomes available, the ladder could be built next summer. That’s when flow is lowest, making it easier to divert water around the construction area.
“It could be a wonderful project for the whole environment of the park,” Mason said. “I’ve listened to several people talk about their youth when they would go out at night and see hundreds of salmon in the creek.”