MARBLEMOUNT — After salmon fight their way upstream in the Skagit River to lay their eggs, they die — providing a source of food for scavengers including bald eagles and black bears but leaving their young defenseless until they hatch.
Seattle City Light, which operates three hydroelectric dams on the upper Skagit River, is tasked as part of its federal license with protecting those eggs if possible.
The goal is to protect 100 percent of the habitat where salmon and steelhead lay eggs between the utility’s Gorge Dam near Newhalem and where the Sauk River meets the Skagit near Rockport.
Seattle City Light fisheries biologist Erin Lowery and Stan Walsh of the Skagit River System Cooperative said the utility consistently protects 97 percent or more of that habitat by maintaining adequate river flows.
Those flows ensure most, if not all, recently laid eggs remain underwater.
While there are certain flow levels the utility knows it needs to maintain during spawning seasons for chum, chinook and pink salmon, as well as steelhead trout, Lowery said adjustments are sometimes needed based on where the fish actually leave their eggs.
“The only way we get 100 percent protection is by making adjustments to our operations based on our weekly surveys,” he said.
That’s where Lowery and Walsh come in. They conduct surveys for recently laid fish eggs throughout the upper Skagit River.
Lowery and Walsh said ensuring flows are adequate for fish eggs is especially important following high flow events such as when the river neared flood stage the last week of November.
Fish that are in the river during high flows have access to areas that aren’t typically underwater. That means if they spawn there, their eggs may be left “high and dry” when normal river flows resume.
To find out if Seattle City Light needs to consider allowing more water through its dams, Lowery and Walsh frequently take a boat out on the river.
Walsh represents the state’s fisheries co-managers during the surveys, as the Skagit River System Cooperative is a natural resources agency for the Sauk-Suiattle Indian Tribe and the Swinomish Indian Tribal Community. Those and other area tribes co-manage the region’s fisheries with the state Department of Fish & Wildlife.
Lowery said the job requires he and Walsh to boat along the river, rain or shine, during about nine months of the year, because different fish species spawn between March and June, August and October, and November and January.
Now through early January is chum spawning season. That means Lowery and Walsh are often out surveying several miles of the river, looking for gravelly habitat where the fish may spawn and for signs of spawning in progress, such as splashing.
When Lowery and Walsh find an area that looks like good spawning habitat or where they know fish have spawned before, they walk through water, mud and brush looking for the subtle signs of egg masses buried beneath mounds of rock.
They record the location of those mounds, called redds, using GPS data. They also measure how far underwater the redds are or how much of the mound is exposed. Walsh said those measurements can help calculate how much of a change in flow could put the eggs at risk or fully submerge them.
If Lowery and Walsh find redds that are on dry ground or only partially in the water, they share that information with the fisheries co-managers.
“Based on the data I collect, we can work with the co-managers to determine if we might need more water to keep the redds covered ... to optimize incubation,” Lowery said.
If the co-managers believe flows should be increased, they collaborate with Seattle City Light.
“We work with the dam operators to find out: Can you release extra water? ... How much water would you need to release (to protect fish) and over how much time?” Walsh said.
Lowery said Seattle City Light typically has to adjust flows out of the Gorge Dam to protect dry or at-risk redds about every other year.
A frequent problem area in the upper Skagit River, known as Washington Eddy, has multiple sand and gravel bars that the river’s changing flows can shift and that are easily inundated by higher-than-normal flows.
“This is one of our most vulnerable spots here, where we can see redds just high and dry,” Walsh said while wading through a side channel at the site on Nov. 29.
Nothing was found amiss at the site during that survey.
During that recent redds survey, Lowery, Walsh and Seattle City Light’s Alan Ferrara saw no redds left on dry ground after high flows earlier that week.
Following heavy rain Nov. 26, the Skagit River was 3 to 5 feet higher than normal the following days between Marblemount and Rockport, according to U.S. Geological Survey data.
During that time, the amount of water flowing in the river in that area reached levels considered a risk to spawning chum, Walsh said.
While the recent high flows didn’t appear to have impacted spawning, in past years they have left several dozen redds exposed.
Since Seattle City Light began managing river flows for fish in 1981, spawning has increased in the upper reaches of the river, including the 25 miles downstream of the dams, according to the utility’s website.
For chinook salmon, which in the Puget Sound region are listed as threatened under the federal Endangered Species Act, the 25-mile stretch of the Skagit River below the dams is the most important spawning habitat available to them, state Department of Fish & Wildlife fish biologist Brett Barkdull said.
About half of the wild chinook that migrate into Puget Sound are from that part of the Skagit River, he said.
Lowery said ensuring recently hatched chinook, chum, pinks and steelhead have a chance to migrate and aren’t left stranded along the banks, sandbars or gravelbars of the river is also part of Seattle City Light’s responsibility in the months following spawning.
The utility is also required to conduct fisheries research and to purchase, restore and enhance fish habitat.
Since its first habitat project in the mid-1990s, Seattle City Light has purchased about 2,700 acres of fish habitat in the upper Skagit River watershed, according to the utility’s website. The utility has also restored and created fish habitat along the river.
The most recent habitat purchase — 61 acres along the Skagit River near Rockport — was made using state Salmon Recovery Funding Board grant money that is intended to protect vital habitat for species with Endangered Species Act protection.
According to a Seattle City Light news release, the property will predominately benefit steelhead.
Ferrara said those efforts to purchase and restore habitat along the Skagit River have had clear benefits for the fish.
The first project Seattle City Light did for fish habitat was near Barnaby Slough, where Walsh said the utility removed large boulders called riprap that were placed decades earlier along the Skagit River’s shoreline to prevent erosion. That project allowed the river to resume natural erosion and create side channels.
Ferrara and Walsh said they attribute those types of projects with helping prevent redds from being left dry or partially exposed.
Lowery said surveys this spawning season suggest the chum in the river have moved into those types of side-channel habitats, which is a natural response during high flows and provides eggs with better protection than in the river itself.