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OID Crews Wrapping Riverbed Restoration
A CAT 735 articulating haul truck dumps gravel into an area of the Stanislaus River at Honolulu Bar which will serve as salmon spawning area. - photo by Photo courtesy of FishBio

Working in conjunction to reestablish salmon spawning and juvenile salmon rearing areas to the Stanislaus River at Honolulu Bar, Oakdale Irrigation District, FishBio, and the U.S. Fish and Wildlife Service’s Anadromous Fish Restoration Program (AFRP) have put in about $520,000 of shared cost into the habitat restoration project. OID and AFRP split the cost 50/50.

Honolulu Bar, which is an island in the middle of the Stanislaus River that can be accessed from an area off Orange Blossom Road, was actually formed from gold mining tailings – piles of dirt and gravel that were dredged from the river during the Gold Rush era. Honolulu Bar is approximately 20 acres. The island formed a side channel of the river that, under most water flows, wasn’t accessible to fish.

The right size, or quality, of gravel is required for salmon and steelhead spawning, so by removing the tailings and returning the suitable gravel to the riverbed, suitable spawning areas are created. OID crews have been at work on the island since mid-June and will finish shortly – in time for the fall salmon run and during typical spring flows, the area will become inundated with water to provide areas for the juvenile salmon to grow.

“We’re adding material back in to help diversity (in the river bottom),” said Jason Jones, OID Support Services (construction) Manager.

He added that they started with about 12,000 yards of the tailings material that was in mounds around the Honolulu Bar area of the river. They put the tailings through a sorter to separate the suitable from unsuitable material. Suitable is considered one-quarter inch to five inches diameter.

The OID crews have created 20-foot wide “benches” – one in the main part of the river and another in the side channel – made of the suitable gravel to create the new juvenile salmon rearing areas, as well as spawning areas, said FishBio biologist Jason Guignard.

Jones added that they’ve also created three “bowls” on part of the island for juvenile salmon to hide and grow. Those areas will be inundated with water at various flows. Guignard said the different elevations created with the gravel are to maximize usage by the juveniles at the different flow levels.

Guignard noted that about 300 or 400 CFS (cubic feet per second) will get water into that area, which is normal winter flow – a level that could not reach the area prior to the project. During high flows, adult salmon go into the side channel and then get stranded there when the flows were reduced.

Jones further explained that FishBio advises placement of the gravel in the river and then the OID crews spread it accordingly.

“FishBio is the biological part. Their specialty is knowing what it’s supposed to look like when it’s done,” he said.

“We were involved in the permitting process…a three- to four-year process,” Guignard added. “We’re providing general biological oversight, water testing … make sure we’re not causing too much turbidity in the river, and things like that.”

OID engineer John Davids reported that the project was originally going to encompass more acreage until elderberry bushes, which host the federally-listed “threatened” Valley Elderberry Long-horn Beetle, were found on the island, even though the beetles are not there. Therefore, the project had to avoid impacting the elderberries but did include relocation of one bush.

Jones recalled that vegetation was so thick on Honolulu Bar that the elderberry bushes couldn’t be seen. They didn’t know the bushes were there until they got into the project. He added that vegetation grinding and removal took about three weeks. Then they did grading of the island, sorted materials, and put the stockpiles back into the river.

Another part of the project includes a re-vegetation plan. Guignard said they will replant around the edges of the island to prevent the blackberry bushes from coming in and the new vegetation will also create shade. There will be annual maintenance, mostly to control the blackberries. The planting will start in November and will include a mix of native plants such as willow, cottonwood, and oak trees, as well as brushier plants and grasses.

Jones reported that there were also a couple of small obstacles to getting the work started. They had to figure out an alternative way into the bar area because the initial route couldn’t handle the weight of the trucks, and they also had a case of vandalism where the windows of the equipment were broken out. Other than that, he said the work has gone well and it has been a good working relationship with FishBio.

“Everything has gone smooth after taking so long to permit,” Guignard agreed, adding, “Hopefully we’ll be seeing some new activity in the gravel we put in.”

The project also includes 10 years of monitoring. That will happen a couple of times annually and also after high flows to make sure everything is flowing right as planned, Guignard said.

OID crews performed all the work, working 10 hours a day, four days a week. Jones said they started the project with two employees, then got up to five employees, and were finishing out the project, two weeks ahead of schedule, with three employees. They’ve used OID equipment, except for a sorter and two haul trucks.

OID got involved in the project so as to mitigate for the loss of six-tenths of an acre of vernal pool credits at a 4:1 ratio for the North Side Regulating Reservoir. That ratio resulted in 2.4 acres to be restored at Honolulu Bar.