How do you rehabilitate the largest body of freshwater west of the Rockies?

In southern Oregon, water quality in Upper Klamath Lake is in a state of crisis. No one knows quite what to do about it

By Alex Schwartz (Klamath Falls) Herald and News, January 19, 2022. It’s obvious to anyone who’s smelled its algal stench in the summer: Upper Klamath Lake needs a good clean-up.

Not only do widespread cyanobacteria blooms turn the shallow lake into unsightly pea soup, they also tank water quality and contribute to mass die-offs of baby C’waam and Koptu (Lost River and shortnose suckers), hurtling the once-resilient species toward extinction.

The lake’s severe state, along with the decline of its endemic fish, limits how much water the Bureau of Reclamation can send down the Klamath River to satisfy flow requirements for threatened Coho salmon, or divert to farms and wildlife refuges in the Klamath Project.

If landowners, scientists and government agencies can improve the water quality in Upper Klamath Lake (and, consequently, life for endangered suckers), it could take a great deal of pressure off water management in the Klamath Basin.

But how do you rehabilitate the largest body of freshwater west of the Rocky Mountains?

Dredging proposed

At 96 square miles, it’s difficult to implement any fix at the scale and swiftness needed to make measurable water quality improvements in Upper Klamath Lake before its suckers go extinct.

Because hundreds of millions of federal funding dollars were recently earmarked for environmental restoration activities in the basin, some people have asked, “Why not dredge it?”

[perfectpullquote align=”full” bordertop=”false” cite=”” link=”” color=”” class=”” size=””]The problem is too many nutrients entering the lake from logging, grazing, stream channeling and irrigation practices.[/perfectpullquote]

Dredging water bodies has been used for decades around the world to achieve a variety of objectives, from deepening lakes to removing polluted sediment. Theoretically, it could do both of those things in Upper Klamath Lake, increasing available storage for irrigation diversions and river flows, while also removing some of the nutrient-rich sediment that fuels its algae blooms.

However, sucking up sediment from a lakebed is extremely expensive ($460 million is the current ballpark figure) and can result in unwanted environmental side effects.

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The latest scientific literature does suggest dredging can be successful, but mainly in lakes that are small and don’t experience consistent pollution from external sources.

“Upper Klamath Lake meets neither of these criteria,” said Megan Skinner, water quality specialist for the U.S. Fish and Wildlife Service office in Klamath Falls.

Industrial runoff

Prior to colonization, it’s likely that Upper Klamath Lake was no Tahoe. The lake is naturally eutrophic, or high in nutrients like nitrogen and phosphorus.

This environment may not yield the clearest water, but it provides the foundation for a robust aquatic food chain. Nutrients grow aquatic plants and microorganisms, which would fuel invertebrates and fish.

The problem now is that there’s too many nutrients entering the lake from its tributaries, released into the watershed by logging, grazing, stream channeling and irrigation practices.

Rivers erode more sediment than they used to, sending excessive amounts of phosphorus directly into Upper Klamath Lake and fueling the domination of toxic cyanobacteria in the water. Thanks to this external loading, researchers now consider Upper Klamath Lake “hypereutrophic.”

‘Techy’ fixes 

The Oregon Department of Environmental Quality evaluated where this excess phosphorus was coming from in the early 2000s.

Approximately 60% in a given year comes from the lake’s own sediments, while 40% enters it from its watershed, including tributaries and lands adjacent to the lake.

ODEQ found human activities responsible for 40% of that external load, mostly through land use changes along the tributaries.

ODEQ set total maximum daily load (TMDL) requirements for Upper Klamath Lake in the early 2000s, requiring a reduction of 40% in external phosphorus.

Skinner has been fielding ideas to improve water quality in Upper Klamath Lake for several years. They range from long-term restoration—such as de-channelization, riparian planting and fencing and spring reconnection—which counteracts the underlying issues of sediment loading.

Skinner said other ideas amount to what she calls “techy quick fixes,” which attempt to alleviate symptoms in the short-term.

The latter category might buy the C’waam and Koptu some time but, at worst, could suck away precious resources that may be better spent on tackling the core of the problem.

“One issue I often run into with these types of projects is scale. What works and is cost effective in a 2-acre lake may cost hundreds of millions of dollars and require monumental effort in a lake as big as Upper Klamath Lake,” Skinner said.

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Dredging is one of those “techy quick fixes” that sounds better than it actually is, at least in this watershed.

It may improve things from a water storage standpoint, but it would easily be counteracted by the continuous loading of excess phosphorus from outside the lake. Plus, it would be prohibitively expensive.

“It may not be the quick fix people would hope,” said Jacob Kann, an aquatic ecologist with Aquatic Ecosystem Sciences LLC. “In a shallow, large lake like Klamath, it’s very difficult to actually treat symptoms.”

Hydraulic pipe dream

Upper Klamath Lake has been dredged before, mainly for boating and logging operations and to build dikes in the early 20th century. But none of those operations occurred at the scale necessary to positively influence lake depth or water quality.

Dredging for those purposes has been brought up since at least the 1970s, when the Army Corps of Engineers evaluated ways to fix the lake’s declining health.

“Lake deepening may feasibly alter lake morphometric characteristics in a manner that will reduce algal productivity. Whether the reduction would be sufficient to justify project implementation on the basis of water quality benefits alone is highly questionable,” the Corps wrote in a 1982 report.

[perfectpullquote align=”full” bordertop=”false” cite=”” link=”” color=”” class=”” size=””]The more than $160 million appropriated by Congress over the next five years isn’t enough to accomplish any one thing.[/perfectpullquote]

After 40 years, the scientific consensus around dredging hasn’t changed much.

Kann said dredging has been part of the conversation since before he began working in the Klamath Basin. The main issue is the influence of external phosphorus on water quality dynamics in the lake. If that isn’t taken care of, the benefits of dredging would only be temporary before becoming eclipsed by an onslaught of new sediment.

But why not dredge to buy the fish some time while we fix the watershed, if removing some phosphorus contained in the lake’s sediment might dampen the severity of the algae blooms?

MORE: Why harmful algal blooms are proliferating throughout the Columbia River Basin

Kann said he hasn’t ruled that out entirely, especially if a project were to focus on smaller phosphorus “hotspots” in the lake, whose sediments contain especially high nutrient concentrations.

Could removing the years of sediments that have already accumulated in the lakebed give us a head start while we restore its tributaries? Kann said his recent research on sediment loading in Upper Klamath Lake suggests that the lake’s “internal loading” may actually be highly influenced by external loading.

Therefore, directly removing sediment from the lake may be more of a Sisyphean task than previously thought.

Other ideas

Stakeholders have to be careful with how they spend limited funding on restoration in the Klamath Basin.

The more than $160 million appropriated by Congress over the next five years isn’t enough to accomplish any one thing, whether it’s dredging Upper Klamath Lake or restoring every mile of the Sprague River. Especially given how close C’waam and Koptu are to becoming functionally extinct in the wild, people have to balance long-term fixes with short-term relief—or choose between them.

Still, there may be measures less disruptive or expensive than dredging that could help make life easier for suckers as partners work to clean up the watershed.

Skinner said she’s already crossed quite a few off her list, but she’s still evaluating activities like killing cyanobacteria cells directly with ultrasound waves or UV radiation, or using oxygen or a compound called Phoslock, which bounds to phosphorus atoms and renders them useless to algae.

“I am always looking for new ideas and therefore encourage readers to reach out if they have any ideas for me to explore,” Skinner said. “I will consider anything and everything.”

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Singer agreed that the basin won’t get anywhere without fixing the underlying problems in the Upper Klamath Lake watershed, but the discussions about dredging or any quick fix underscore just how dire the situation is for suckers. Without some way to keep the species alive in the interim, would water quality improvements from tributary restoration arrive in time?

“I think it’s important to focus externally, but I still wonder if there’s a way to just, you know, get some oxygen to the poor fish,” she said.

Columbia Insight is publishing this story as part of the AP StoryShare program, which allows newsrooms and publishing partners to republish each other’s stories and photos.