‘Arcata is not going to be here’ – city to adapt, protect and retreat from sea level rise

Arcata Community Development Director David Loya displayed a map indicating areas of Arcata (in purple) that are vulnerable to inundation with rising sea levels. KLH | Union

Kevin L. Hoover
Mad River Union

ARCATA – “By 2050, this will be normal,” said Aldaron Laird, standing near the top of an Arcata wastewater treatment pond levee as waves broke at his feet.

A small group had trekked out to the Rising Tides Bench during a nine-foot King Tide on Dec. 13 for a discussion of sea level rise, its imminence and consequences.

While the bay’s present borders can more or less withstand today’s King Tides – also known as perigean spring tides, which coincide with maximum gravitational pull by the moon and sun – that won’t be the case when they ride in on top of tomorrow’s raised sea levels. At that point, seawater would overtop current levees and inundate coastal areas, including homes, farms, businesses and critical public infrastructure.

The higher sea levels are not an “if,” they’re a “when.” What we don’t know is exactly when.

And it won’t stop there. By 2100, some projections indicate sea level rise of over six feet, possibly much more. That’s why, at an Arcata City Council study session on sea level rise that same night, Community Development Director David Loya stated, “Arcata is not going to be here in the future.” Pointing northeast in the direction of the hills, he said, “It might be there.”

Humboldt Baykeeper sponsored the Rising Tides walk along the marsh oxidation pond levee. KLH | Union

The levee walk and the later council study session offered both a reality check and a gut check as regards the cataclysmic challenges ahead.

In one day, the minute number of Arcata residents who participated in the two events – a few dozen total – learned about what’s coming and ways the city might respond.

Out on the bay, Laird noted that sea level rise could render some initial areas uninhabitable even as streets remain dry, by flooding out underground utilities such as sewer lines.

With the bay protected by 41 miles of aging dikes, Laird said, “We’re all living on borrowed time.”

How much time there is to do something, and what, were key points in the discussion at Arcata City Hall that night. Senior Planner Elizabeth Schatz laid out the big picture with a comprehensive overview.

Exacerbating the problem locally is that the water level isn’t just rising – the land is sinking. Tectonic forces are pushing Humboldt down, the subsidence compounding the problem.

As bay levels rise, said City Engineer Doby Class, Arcata’s creeks won’t be able to drain properly. Storm drains will back up and water will pool upstream, flooding near-creek areas.

The Bloomfield neighborhood is a prime example. “All that’s underwater,” Class said.

“Our streets will become Venice,” Class said. He noted that “entire nations live that way,” protecting developed areas with dikes and pumping water out into the sea.

“Tourism opportunity!” blurted Councilmember Sofia Pereira, half in jest.

Humboldt Baykeeper’s Jen Kalt, who had also participated in the earlier bay walk, said areas likely to flood should be assessed for toxic hot spots and other pollutants that could mingle with the rising waters.

The “punch line,” Loya said, is that “it’s going to impact the City of Arcata big time if we don’t do anything.”

The strategy is shaping up as armor and protect critical assets for as long as it’s cost effective, then pull back.

Which areas will get protection will be the most difficult thing to decide. Councilmember Mark Wheetley noted that lower H Street and other bay-facing areas are the “biggest concern.” Class said State Route 255 presents a natural barrier, or “default levy.” But it is far from impermeable.

“Arcata’s boundaries are shrinking,” Class observed.

Loya showed a slide indicating areas that might be safely protected by improved levees. Numerous gaps in the levees could be filled and their height raised, thus enclosing selected areas of town deemed worthy of preservation.

Identifying those areas via cost/benefit assessments will be among the difficult decisions required of planners, politicians and the public in years to come. Integrating them into the Local Coastal Plan promises to be daunting at best.

While the Coastal Commission presently disallows filling of wetlands, that is effectively what would occur once they’re diked in. The agency may have to revisit even that most sacrosanct policy as the waters rise, or doom coastal communities to inundation.

“Where would we find mitigations?” wondered Julie Neander, deputy director of community services. “It’s a whole new world,” Class noted.

As the ocean creeps in, Arcata will do what mammals everywhere instinctively do when pursued – climb. Referring to the town’s higher elevations, Loya said, “We’re starting to annex that way. Over time, we’re going to start building that way.”

While this fundamental shift is outside the current “planning horizon,” Loya said, “At some time it’s going to be infeasible to protect the assets we have.”

Among the assets considered worth protecting, or “armoring” via raised levees and protected access would be Arcata’s Wastewater Treatment Facility, located at the Arcata Marsh & Wildlife Sanctuary. Currently undergoing upgrades, the plant should be all right for another 40 years if walled off against the water.

Class called the eventual state of things there “a road to an island.”

Complicating the planning is that projections of sea level rise vary wildly. While inevitable, specifics are elusive. “We’re fumbling in the dark here, just to be honest,” Loya said. Nonetheless, he said, it’s crucial to “design a retreat strategy.”

Laird said that once the wastewater plant becomes too costly or impractical to protect, it may be most practical to “think outside the box” and create a regional treatment facility to replace it.

“Luckily, this council won’t have to make that decision,” Loya assured wide-eyed councilmembers.

Environmental Services Director Mark Andre repeatedly offered assurances that the current treatment plant will be safe and useful for years to come. “We think we can fortify that spot for a long time,” he said.

He said that there are 35 treatment plants in the Bay Area that are similarly vulnerable, with plans afoot to fortify them.

Loya said piecemeal fixes won’t do. “One project at a time – that’s not planning,” he said. He suggested that a regional approach, possibly a  joint powers authority, might be best suited to craft an overall “adapt, protect, retreat” strategy.

Andre, the voice of calm amid the startling revelations, pointed out that Amsterdam, the Netherlands city which is more than six feet below sea level, “has been living like that for a long time.” Of town-protecting levees, Andre said, “You can almost engineer anything with enough money.”

Inevitably, property values in some areas are going to plunge, while others are going to become more valuable.

Councilmember Mark Wheetley said that developments within areas likely to flood should be charged an impact fee to offset public costs for protecting those assets.

Councilmember Susan Ornelas said a regional group might be assembled, and that community outreach must be done to ensure public involvement in the decision making. It doesn’t have to be a grim undertaking, she said, but an opportunity for citizens to imaginatively redefine the town.

“It could almost be a pinnacle time,” Ornelas said. “We can plan with creativity and not just work off of our fears.”

Loya later laid out the initial approach, which will ramp up in January. At least two more council study sessions will be held, each getting more specifics as to what’s in store.

A “gap analysis” will be done to identify where levees might be completed in order to encircle town assets, and projections will be refined.

The public will be asked to prioritize which properties ought to be protected. More tours of the most exposed areas will be held, using the Arcata Marsh Interpretive Center as a starting point.

From all of this, a process and policy objectives will emerge. The Arcata Planning Commission will be charged with developing specifics, which will then be handed up to the Arcata City Council.



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