Posted on 10/11/2022 3:56:47 PM PDT by nickcarraway
The dam, taken down last month, held back cobbles, pebbles and gravels that environmentalists say is critical to bolster dwindling populations of Central Coast coho and steelhead
Amidst fire-blackened redwoods, lush ferns and hazelnut bushes of the San Vicente Redwoods, Mill Creek waters are flowing freely again after a 110-year-old dam — that was never functional to begin with — was removed.
The dam, taken down last month, held back cobbles, pebbles and gravels that environmentalists say is critical to bolster dwindling populations of Central Coast coho and steelhead.
“This is one of the southernmost watersheds for coho and their entire population,” said Ian Rowbotham, land stewardship manager with conservation nonprofit Sempervirens Fund. “The hope is that through this work you can start to see those populations rebound dramatically with increased and improved habitat.”
The dam, which spanned roughly 25 feet wide and 12 feet tall, was a choke point for steelhead attempting to move upstream. Its removal, led by Sempervirens and financed by Resources Legacy Fund, cost more than half a million dollars.
“It’s not a huge stretch of habitat that’s being opening up, but it’s really vital habitat — paired with the gravel moving downstream, it means new spawning potential, additional pools and habitat for fish to feed and space out,” Rowbotham said.
Sunlight streams upon granite cobbles and pebbles in Mill Creek. (Hannah Hagemann — Santa Cruz Sentinel) Last August, some of the first lightning strikes — of hundreds — touched down in the 8,532-acre San Vicente Redwoods forest, igniting a part of what would become the CZU Lightning Complex fire.
Parts of the landscape, managed by Peninsula Open Space Trust, Sempervirens Fund and Save the Redwoods League, were burned severely, transforming fertile soil to dust.
Other regions, particularly near Mill Creek, saw low-intensity fire. That fire consumed built up leaf litter, and unhealthy fuel, said Rowbotham, similar to how a prescribed burn works.
The blaze also expedited the dam removal. Since the fire burned a Davenport drinking water supply line that ran across the Mill Creek Dam, the infrastructure no longer served a purpose. That water line has since been relocated, away from the dam.
After at least four years of work to bring it down, the final dam removal took a mere 90 minutes.
To prepare for the demolishment, contractors temporarily relocated fish and siphoned water off the creek, a process that took about a week. The dam itself, made of rock and mortar, was easily torn apart by excavators.
When surveying and moving the fish, crews counted at least 15 steelhead at a pond near the base of the dam, according to Rowbotham.
Ian Rowbotham, land stewardship manager with Sempervirens Fund, points to old waterlines that were once supported by the Mill Creek Dam. Those lines have since been relocated. (Hannah Hagemann — Santa Cruz Sentinel) “We anticipate that these fish would potentially be the first fish moving into the area above the dam for the first time in 100 years,” Rowbotham said.
‘Magical place’ Both steelhead and coho live in freshwater streams and the pacific ocean’s saltwater for parts of their lives. During the rainy season, steelhead migrate from the ocean to local streams, to spawn, only if water conditions are right.
Coho salmon live their first year in freshwater streams, then spend around 18 months in the ocean. The fish then attempt to return to the waters in which they came from, to spawn and die.
Once plentiful in Santa Cruz County watersheds, Central Coast coho are listed as endangered, or on the verge of extinction, under the Endangered Species Act. Central Coast steelhead are threatened, according to the National Oceanic and Atmospheric Administration Fisheries.
Mill Creek is unique in that its waters are particularly cold, and underlying granite and limestone bedrock cultivates ideal spawning material, said Jim Robins biologist and principal with Alnus Ecological.
Where it merges with San Vicente creek and flows out to the Pacific near Davenport, two manmade tunnels create a highway for coho and steelhead between fresh and brackish waters that’s almost always open.
Ian Rowbotham, land stewardship manager with Sempervirens Fund, stands in a newly forming stream channel, where water and sediment was previously held back by a more than 100-year-old dam. (Hannah Hagemann — Santa Cruz Sentinel) “Whereas most of our estuaries have sandbars that close and with drought can create massive problems for fish getting in and out, this is this unique watershed where fish can get in and out any time of year, it doesn’t close, it’s always open,” Robins said. “From a coho salmon and steelhead perspective, it’s just a magical place.”
The removal of the dam clears the way for the fish populations to make it to the ocean for a stretch of 6 miles.
The work that’s led up to the dam’s release has been years in the making. Robins and others built woody debris structures to ensure the sediment washing down will be trapped and deposited, so fish can utilize it.
But it’s not clear yet how long it will take the newly wild channel to take shape and the benefits to take ahold.
“If we get enormous storms, the gravel and material will move out quickly,” Robins said. “If we get winters like the last few winters, it won’t move quickly at all.”
Still, the work cements hope that the once plentiful fish species could rebound.
Recently, the city of Santa Cruz reported its documented juvenile coho in the Laguna Creek lagoon for a second consecutive year.
Work to come Before the dam was removed, Amah Mutsun Tribal Band members completed cultural, anthropological and ethnobotanical surveys.
“Over time the dam removal will allow the creek to return close to its natural state, and that’s really important, for the wildlife, fish, plants and other relatives,” said Amah Mutsun Tribal Band Chairman Valentin Lopez.
The Tribal Band plans to hold an intimate ceremony later this year to call back coho salmon to Mill Creek and encourage their numbers to grow.
Amah Mutsun Tribal Band members who are a part of the Native Stewardship Corps, are also documenting changes following the dam removal, in a collaboration with UCLA researchers.
As part of the project the team is taking water samples, and testing for eDNA, or environmental DNA.
The cobbles, gravel and sand held behind Mill Creek dam is critical to bolster coho salmon and steelhead populations, scientists and environmentalists say. That material will wash down in the coming years, but how quickly that happens depends on how much rainfall the region receives. (Hannah Hagemann — Santa Cruz Sentinel) “Our research is geared towards restoration and understanding how to better steward and manage salmon,” said Research Analyst with the Amah Mutsun Land Trust, Mike Grone. “A lot of the creeks and streams along this coastline used to have coho populations and don’t anymore.”
The project, set to take place over the coming years, is interdisciplinary and melds scientific practice with Indigenous knowledge.
“If we can understand all those variables, maybe we can understand a way to return coho,” Grone said.
Why would CA need water? Bunch of braindead libs.
The real story on coho salmon in Santa Cruz County.
Steelhead, yes. Coho, not without the hatchery.
Ridiculous hyperbole.
They have other fish to fry.
Ridiculous hyperbole.
>> Come on. Be a sport. Don’t waters running free get you right in the heart? I mean, that water was in prison before. Chains, beatings, lousy meals the full monte. Now it’s free!
Cobbles and pebbles and gravels, oh my!
I guess it was never worth the effort for these enviro-wackos to shovel some gravel into the creek here and there to help out the salmon and steelhead.
I am thrilled that the Indian band will get together to “call” the coho salmon to come back and breed.
I. Am. So. Sure.
Someone is is trying to sound like an intellectual.🙄
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