🌡 How Warm is an Underwater Cable? What the Science Says - EFSEC Sept '26

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🏛 September 2026 EFSEC Round-Up

Agencies Covered: Washington State Energy Facility Site Evaluation Council (EFSEC), meeting of September 16, 2026.

The Bottom Line: The Council spent well over an hour on the Cascade Renewable Transmission line and decided nothing yet, on purpose. Staff will start drafting the land use decision, and whether to hold another hearing gets decided in October.

The Vibe: Patient and a little tangled. Three jurisdictions, two states, a federal Scenic Area and a treaty fishing site, all meeting at the bottom of one river.

🔎 What Changed

• EFSEC released its summary of the 772 comments on the power line's land use information, and its EIS scoping report.
• Badger Mountain Solar is off the books. Avangrid withdrew the application on July 20.
• Ostrea Solar held a ribbon cutting with Governor Ferguson on September 2.

⚠ What Escalated

• Tribes and conservation groups are asking for new hearings in all three counties, and two of them ask the Council not to find the line consistent at all on the current record.
• EFSEC confirmed its notice for the Skamania County hearing in November 2025 never ran in the local paper before the hearing.

🧭 What's Next

• At its October meeting the Council is set to see a segment-by-segment map of which rules apply where, and to decide whether to hold another land use hearing.
• Staff said a draft land use decision would go out for written comment before the Council takes it up, which staff put in November.

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🕯️Cabinet of Curiosities: Halloween in the Gorge

Before trick-or-treating, Halloween in the Gorge meant two things: a party, or a prank.

The phrase "trick or treat" didn't even show up in print until 1917, in a newspaper up in Ontario. Here, that same October, the Underwood school threw its Halloween party. There was a marshmallow race, apple bobbing, a peanut hunt, and a game called "hitting black cat." The Perry boys won three of the four. Carl Kapp took the apple bobbing. Then came cider and doughnuts, and the paper made sure to thank R.E. Steele for the cider.

The next October, there was no party at all. The school had been sent on what the paper called an "enforced vacation," and the Halloween party was cancelled. That was the fall of 1918, when towns across Washington closed their schools and churches to slow the flu. Underwood's notes only report "the ban on public meetings lifted" at the end of November.

By 1923 the parties were back. The Underwood Christian Endeavor invited everyone to the old Climax mill cook house on October 31st, for apples, cider and doughnuts.

And if you weren't at a party... you might have been up to something. In Stevenson, Philip Doumit remembered the Halloween a group of men hoisted a dray wagon onto the roof of the fire department building. Outhouses got tipped over every year, "to the amusement of only the tricksters." His own store windows got smeared with candle wax, and he spent hours scraping it off. Years later, he wrote that trick-or-treating by "the small fry" was "a welcome change from the past."

Now... on to this month's EFSEC business.

Washington State Energy Facility Site Evaluation Council

🌊 The Power Line: 772 Comments and One Big Question

The Cascade Renewable Transmission line would carry 1,100 megawatts of direct current about 100 miles from The Dalles to Portland, mostly buried in the bed of the Columbia. About 40 of those miles are in Washington, along Skamania, Klickitat and Clark counties, including about 7.6 miles of cable under the road near Stevenson and North Bonneville to get around Bonneville Dam. (Our February special report has the full background.)

From July 27 to August 26, EFSEC took comments on the developer's updated land use information. The staff summary counts what came in:

• 772 submittals. 729 were campaign emails built on two form letters. The other 43 were read one by one.
• Of those 43, staff judged that 12 dealt with the updated land use information, 5 did in part, and 26 were about other things: the environment, safety, need or cost.
• Staff were careful to say the summary "does not recommend an outcome."

The big question is whether the National Scenic Area rules reach into the river itself. The developer's position is that the river carries no Scenic Area zoning, so the Management Plan doesn't apply to the in-river route beyond a Forest Service consistency review. Six submittals disagree, on different grounds. The Confederated Tribes of Warm Springs argue that no zoning is not the same as no rules, because the Plan protects scenic, cultural and natural resources everywhere in the Scenic Area. The Yakama Nation points out that about 31,500 acres of the river lie inside the General Management Area. The Umatilla tribes, and Friends of the Columbia Gorge together with Columbia Riverkeeper, argue that in the Scenic Area an unlisted use is not allowed rather than allowed by default. Staff wrote that the two readings "are mutually exclusive and rest on the same undisputed fact," and that the Council has to pick one, on the record.

Three specific conflicts were alleged, the only ones in the whole set:

• Columbia Riverkeeper says the route runs lengthwise through shoreline that Skamania County's shoreline program designates "Natural," where utility corridors aren't allowed if they can go elsewhere.
• Commenter M. Repar raised the same Skamania rule plus the City of Stevenson's shoreline program.
• The Yakama Nation argues that the concrete mats and rock placed over the cable to protect it from scour count as shoreline armoring under Skamania and Clark county codes, and asks for modeling of how deep the cable needs to sit to stay buried as the channel shifts.

Commenters also flagged holes in the record. The North Bonneville Treaty Fishing Access Site and the Bonneville In-Lieu Site don't appear in the developer's analysis, though the road segment is said to pass just north of the in-lieu site. Stevenson's and North Bonneville's own zoning isn't analyzed. And no city or county has filed a certificate saying the project fits its rules.

🗣 What the Council Said

The meeting was a briefing, not a vote. A few points stood out.

What the land use decision actually decides. Assistant Attorney General Jon Thompson, the Council's legal adviser, said the determination is narrow. It asks only whether a power line is flatly prohibited in each zone along the route. If it's allowed with conditions, that counts as consistent, and the conditions get handled later. If it's prohibited, the project isn't dead; it moves to a trial-like hearing on whether the state should override the local rule. State law defines the local rules in play as plans and zoning adopted under the state's planning statutes or under the state constitution's grant of local power. Whether a county's Scenic Area code counts is the open question.

The Scenic Area is someone else's call, in his advice. Thompson said the Scenic Area ordinances, including Skamania County's Title 22, carry out federal law through the Oregon-Washington compact, so EFSEC can't apply them or override them. The developer would still have to satisfy them through the county, with appeals to the Gorge Commission. Councilmember Kate Dean, who came from county government, asked why: counties adopt plenty of federal maps into their own codes, so why is this different? The Council hasn't decided that question.

That's not the end of it. Skamania County, the state Attorney General's office and the Gorge Commission have been working on an agreement that would let EFSEC review the project under the county's own Scenic Area code, Title 22 (as we reported in July). County Public Works said in September the agreement is "in the AG's hands" (September). Thompson floated the same route on September 16. The Gorge Commission itself has declined to take a position on the line, because it could hear an appeal (our June–July coverage).

Councilmember Jan Sokol of Klickitat County added that whatever EFSEC concludes, the federal permits, the Gorge Commission and the state Department of Natural Resources' riverbed lease all still have to happen. Thompson also said Klickitat County's shoreline program "clearly does apply in the river." This is the same line we reported in July, when staff told Skamania County its local permits fold into EFSEC's. September drew the edge of it: the Scenic Area rules don't fold in.

The notice that didn't run. Councilmember Aaron Peterson asked about a commenter's claim that the Skamania County hearing was never published in the county's legal paper. Ami Hafkemeyer, EFSEC's director of siting and compliance, confirmed it: EFSEC sent the notice, but it "did not run in the issue of the paper prior to the meeting." It is unclear if this was an issue on the paper's end. Staff also walked through why the November hearings came before some local members were seated: state law gives EFSEC 60 days to hold the informational hearing but sets no such deadline for the land use hearing, and neither November hearing decided land use consistency. Commissioner Leckie later gave Skamania County commissioners his own account of the meeting (September).

Another hearing, or not? Members split.

• Councilmember Asa Leckie of Skamania County offered to move for another hearing and said residents deserve one in person, because land use consistency "has not been addressed in a public format." Leckie added that a hearing would give the tribes more room to weigh in after the summer's consultations.
• Councilmember Nate Pamplin of Fish and Wildlife said a hearing with the full Council seated "would be beneficial."
• Councilmember Blake Nelson of Ecology said the three in-person hearings plus 772 comments met the public-comment duty, and suggested a virtual meeting if the Council wants all local members present.
• Dean wants to see the segment-by-segment table first and decide in October. Dean also asked for a briefing on how tribal treaty rights bear on the decision.
• Councilmember Brian Rybarik of the Utilities and Transportation Commission agreed with Thompson on the Scenic Area and wants the Council to consider limiting any new hearing to issues EFSEC can decide.

Chair Kurt Beckett asked staff to start drafting the decision documents now, saying that presumes no outcome. Leckie worried it could look like a decision already made. Beckett said for the record it isn't, and that he would wait if it would be misread; Dean and at least one other member backed drafting early as normal practice. Staff will line up venues in case the Council wants a hearing, which Beckett said would realistically fall the week before Thanksgiving.

As of October 1, we found no other coverage of the comment summary or this meeting.

🌡 Heat, Magnetic Fields & Fish: What the Science Says

Two worries come up again and again in comments on this project: that the cable will warm the river, and that its magnetic field will confuse fish. These are reasonable questions, and deserve scientific answers. (Our February special report made the same point: the cable isn't "magic safe," and it isn't automatically an ecological disaster.) These are reasonable questions to ask, and we can look to the latest research science to help us find evidence-based responses to them.

The claim. Columbia Riverkeeper wrote in an April letter that "the skin temperature of the cable will reach 158 ℉ and continually discharge heat into the Columbia River." The Columbia River Inter-Tribal Fish Commission's scoping letter says the cable "will operate at temperatures up to 158°F." Riverkeeper's August campaign post says the line "could add heat to 100 miles of an already overheated river." Neither letter says where 158°F comes from. It matches 70°C, a common rated maximum for the copper core of this type of cable. If that is the source, it describes the hottest the copper core is rated to run, not the cable's outer surface, the mud around it or the water above it.

The river. The river's heat problem is real, the direct results of a warming climate. Water at The Dalles Dam ran above 20°C, the danger line for salmon, on 81 days in 2025, according to Save Our Wild Salmon data as Columbia Gorge News reported. But the cable can't add much to it. We did the math, and had it checked by a professional physicist. At full power, two cables this size lose roughly 30 to 50 watts of heat per meter, or about 4 to 6 megawatts along the whole riverbed. Even if every watt went straight into the water, with nothing soaked up by the riverbed, the Columbia at its average flow of about 188,000 cubic feet per second at The Dalles would warm by two to three ten-thousandths of a degree. At a low 50,000 cubic feet per second, it's still less than a thousandth of a degree. The river's temperature trouble comes from slow, sun-warmed reservoirs and a warming climate, which is what the EPA's 2021 temperature plan for the Columbia addresses. A buried cable is unlikely to meaningfully change that.

The riverbed is another question. Heat that can't move the river can still warm the sediment right around the cable. Germany's offshore regulators cap that warming at 2°C, measured about 8 inches below the bed, to protect animals that burrow (OSPAR 2009; Emeana et al. 2016). Burial depth is the main way to meet it. In the Columbia, the animal people worry about most is Pacific lamprey, whose young live buried in riverbed sediment for years. But they live near the surface. In U.S. Geological Survey tests with Columbia River larvae, most burrowed within the top 3 inches of sand, and none went deeper than 6 inches (USGS 2015). The developer says the cable would sit about 10 feet down along most of the route, which Columbia Insight also reported. That's far below them. Where it could matter is where the cable can't be buried that deep. It also necessitates having effective monitoring systems in place to ensure cables remain buried at their expected depth.

The draft application, as Riverkeeper's December letter quotes it, expects "no thermal effects on habitat for benthic prey species" along 97 percent of the route because of that depth. Where bedrock or boulders prevent burial, the cable would be covered with concrete mats or rock berms, which the application estimates would cover about 2.4 acres of riverbed, and it expects "minor localized rises in ambient temperatures" there. So far the thermal modeling is the developer's own. Independent, Columbia-specific study of those stretches is what Riverkeeper and Friends of the Columbia Gorge asked for in their June scoping letter, and what the tribal fish commission asked for too.

Magnetic fields. A direct-current cable makes a steady magnetic field, like a small local bump in the Earth's own field. Water moving through it makes a weak electric field too. The two cables carry current in opposite directions and are bundled together, which cancels much of the field, and it fades quickly with distance. Columbia Gorge News reported in March that, according to the application, stretches buried less than two feet deep would push the magnetic field above natural background.

Do fish notice? Some do. Studies of real cables have found this:

• On a direct-current cable under San Francisco Bay, young Chinook salmon seemed somewhat drawn to the cable, and green sturgeon travel times shifted. But the share of fish that completed their migrations did not change in a statistically meaningful way (Wyman et al. 2018; federal study). Riverkeeper's scoping letter reports that study accurately, including that the dips in migration success were not statistically significant.
• Over a cable in Long Island Sound, skates got noticeably more active and lobsters slightly more so, but neither was blocked from crossing (Hutchison et al. 2020).
• An international science review in 2020 concluded that animals near power cables "are not likely to be harmed by emitted EMFs" (OES-Environmental).

What nobody has yet studied is a cable like this one in a narrow river, with adult salmon heading upstream to spawn, and with lamprey and white sturgeon. A 2025 review called for more research on how these fields affect fish migrating to spawn. So the fair summary is: fish can sense these fields and some change their behavior; harm to fish populations hasn't been shown; and "no effect at all" isn't what the studies say either. These studies provide strong foundations to ensure we're asking the right questions.

How new is this? As technology, not very. The first direct-current power cable laid underwater, to the Swedish island of Gotland, went into service in 1954 (IEEE history). Running one along a river for most of its length is rarer. The closest match is New York's Champlain Hudson Power Express, a 1,250-megawatt, 339-mile line routed under Lake Champlain and the Hudson River and along rail and road rights-of-way, which began commercial operation in May 2026. What is new here is the place: a dammed river with treaty fisheries and runs of salmon, lamprey and sturgeon. This is why an individual review of each project, as is part of EFSEC's process, is necessary and important.

What happens next on this. EFSEC's scoping report lists "cable operating temperatures" and magnetic field effects on migrating fish among the most raised topics. It also lists lamprey, white sturgeon and freshwater mussels by name. It counts about 65 comment submissions and 100 people at the May scoping meetings. The report is not the final scope. EFSEC still has to issue a Scoping Decision, and then a Draft EIS, which will go out for public comment. The Army Corps of Engineers is writing the federal environmental review, and EFSEC expects to adopt it and add Washington-specific analysis. One more open legal question: Riverkeeper argues the cable needs a federal water-quality discharge permit, and the tribal fish commission asks EFSEC to settle the question. The Clean Water Act counts heat as a pollutant, but a permit also requires a "point source," and whether a buried cable is one hasn't been decided for this project.

Editor's Squiggly Note: Pacific Lamprey have a special place in our hearts over here at the Dispatch. We welcome you to read more about the restoration efforts of this important and often underappreciated creature. This includes a rebuilt fish ladder at Bonneville Dam to help our boneless friends make their way up the river with less exhaustion. We look forward to seeing updated, best available science continue to help us ensure the future of this species.

☀️ Carriger Solar: The Cleanup Plan Slips

The 14-day public comment period on Carriger's site restoration plan, expected the week of August 24, didn't happen. Joanne Snarski of EFSEC staff said the developer and the Yakama Nation chose to work directly with each other on the tribe's comments on three pre-construction plans. Second drafts were expected within about a week of the meeting. The Yakama Nation has asked for 45 more days to review them. The plan still needs a public comment period and a Council vote. Chair Beckett also said the project's official milestone list should show the court appeal, which the September list left out. Carriger is the 160-megawatt solar and battery project about two miles west of Goldendale.

🔆 Ostrea Solar: A Ribbon Cutting Before "Operational"

Governor Ferguson and members of the Council attended a ribbon cutting at Ostrea Solar in Yakima County on September 2, per the developer's own report. The same report, and the one before it, still list the site as "Construction" and "Not yet operational." Final performance testing is done, but the results are still being checked against the pass criteria. A county weed board inspection in August found "large quantities of weeds over desired species," and reseeding guidance is going into the site's weed plan. Councilmember Rybarik congratulated the team while noting it was "maybe not exactly commercial operation quite yet."

🔧 The Rest of the Fleet

• Badger Mountain Solar (Douglas County) is gone. Avangrid had asked in July for another year's pause, citing Bonneville Power's transmission delays, then withdrew its application on July 20. EFSEC Director Marco Lowe told the Council it had notified the tribes and counties.
• Columbia Generating Station reported that in July, up to 10 gallons of non-hazardous compressor oil may have leaked into a cooling-water system that can drain to the Columbia. The failed part was replaced within days and the cause is under investigation. It follows two turbine-oil leaks the plant reported to the Council in June.
• Goose Prairie Solar disclosed a manufacturing defect in its tracker bearings, being fixed under warranty, and a July outage alarm that went unnoticed because it was buried under 2,631 wind alarms; the site was back online the same day.
• Horse Heaven (Benton County): staff are moving a bird and bat fatality monitoring plan toward approval. The project's challenge at the state Supreme Court, was argued June 11; as of the September meeting, no decision had come.
• Hop Hill, Wallula Gap and Goldeneye continue in review. Hop Hill expects to file a substantially redesigned layout in fall 2026.
• New rules on hearings, applications and cleanup financing may come before the Council in October, per staff.

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⚠️ Editor's Notebook: Broader Context

• Two different decisions are getting tangled. The land use question (is a power line flatly banned somewhere along the route?) is narrow and comes first. The environmental question (what does it do to the river, the fish and the treaty fishery?) is the EIS, and it comes later. The heat and magnetic field arguments belong to the second one.
• The Scenic Area runs on its own track, for now. If EFSEC's lawyer is right, no EFSEC decision settles whether the line complies with the Scenic Area rules; that runs through Skamania County and the Gorge Commission, unless the Title 22 agreement lets EFSEC take it on. EFSEC's own staff summary, meanwhile, says the Council has to resolve the Scenic Area question on the record. Those two positions haven't been reconciled.
• Plenty is still unknown. The exact mileage the cable can't be buried, how warm those stretches get, and how adult salmon, lamprey and sturgeon respond in this specific geographic location and ecology. Those are the fair questions for the EIS to investigate and answer.

🛠 Jargon Buster

• Land use consistency: EFSEC's check of whether a project fits local zoning along its route. EFSEC's lawyer describes it as asking only whether the use is flatly prohibited. It is not an approval.
• Certificate of consistency: a statement from a city or county that a project fits its land use rules. None has been filed for this line.
• EIS scoping: the step where the public tells the agency what the environmental study should cover.
• HVDC: high-voltage direct current, the kind of power line that moves large amounts of power long distances with less loss.
• Concrete mattress: a mat of linked concrete blocks laid over a cable where it can't be buried.
• In-lieu site: a fishing site set aside for treaty tribes to replace usual fishing places flooded by the dams.

📅 How to Join & Learn More

• EFSEC meets monthly, usually on the third Wednesday at 1:30 p.m., hybrid from 621 Woodland Square Loop SE in Lacey. Agendas and the join link are on EFSEC's meetings page.
• Project documents, including the comment logs, live on the Cascade Renewable Transmission page.
• Comment anytime at comments@efsec.wa.gov.