On June 11 the City of Salem discussed several approaches it will take to treat the city’s drinking water so that cyanotoxins from harmful algal blooms (HABs) will no longer threaten human health.

The costs presented were not insignificant. To add chlorine, powdered carbon and diverted ground water to the water that descends from Detroit Lake to the Garen Island Water Treatment Facility will require $2 million annually for the next two years. The city announced it will also explore a more comprehensive approach; creating the means to integrate ozone into Salem’s water system on an ongoing basis for a $20 – $30 million expenditure.

What causes the blooms that will cost our community these resources?

Algae are simple organisms that thrive on heat, nutrients and sunlight. In recent years heat and nutrients have increased in the Cascades above Detroit Lake, and in important part because of the actions of people – sometimes in ways that are manageable. This makes the water of the North Santiam watershed that feeds into Detroit Lake still somewhat under human control before it ever reaches Garen Island for the chemical treatments the City is exploring.

Because the factors that lead to HABs are intertwined, exploring them can be instructive.


Timber practices

Timber clear cuts have long been associated with dangers to waterway health. Chemical sprays and dirt slides from logging roads dump soil and chemicals into mountain streams, and loss of vegetation to shade these waterways increase temperatures, putting species like salmon in peril.

Logging influences algae as well. “Any type of land disturbance, such as clear-cutting, leading to exposure of soils to erosion, will lead to increases in nutrient loss from soils,” says Dr. Hans W. Paerl, Kenan Professor of Marine and Environmental Sciences from the UNC-CH Institute of Marine Sciences. The same nutrients that damage salmon wash downstream into Detroit Lake, scientists say, where they feed algae.

“Clear-cutting is a common practice in the watershed above Detroit,” says Salina Hart, Chief Reservoir Regulation & Water Quality Section, U.S. Army Corps of Engineers. “It has been shown that extreme logging practices can lead to additional sediment and nutrient loadings to streams and rivers.”

In “nature’s perfect system,” forests assist a healthy water cycle, according to Tina Schweickert, former Water Resources Coordinator for the City of Salem Public Works Department and an environmental advocate who has studied the watershed surrounding Detroit Lake. “As forests grow, fed by water and nutrients from the soil and air, they transpire, breathing moisture into their surroundings. The trees and forest floor filter rainwater, store it in the ground for slow release, keep soil intact, and provide essential nutrients and structure for aquatic ecosystems, which in turn help clean the water.” 

Logging disrupts this process, not just by sending nutrients and chemicals down watersheds to nourish algae in lakes like Detroit – but because it also warms the region. A recent study shows that Oregon logging is overwhelmingly the most significant source of greenhouse gas emissions in the state. In, OSU Research Confirms that Big Timber is the Leading Source of Gas Emissions In Oregon, John Talberth of the Center for Sustainable Economy, writes that Oregon logging has produced more than 33 million metric tons carbon dioxide equivalent every year since 2000. “This makes logging by far the largest source of emissions in the state, far larger than,” the 23 million metric tons attributed to transportation, Talberth says.

Private lands, observes Schweickert, “are not well regulated, and can be clear cut with little protection to watersheds and stream corridors.” Although much of the land above Detroit Lake is owned by federal agencies, satellite maps of the region show significant private timber plantation clear cuts and logging roads. In fact, some recently clear-cut private forests drain directly to Detroit Lake itself, with no buffer of forested lands.


The Bull Run difference

Comparing Detroit Lake with Portland’s water source, known as the Bull Run watershed, can highlight some of the factors that trigger HABs. Bull Run is a 102 square acres area with two reservoirs located east of the city in the Mt. Hood National Forest. With almost 8 times less water by volume than Detroit Lake, Bull Run collects drinking water for 1/4 of Oregon’s population and has never yet had an HAB.

There are numerous differences in the ways the watersheds are managed. Unlike Detroit Lake, with its pontoons and speedboats, activities in the nearby city of Detroit, sewage and timber runoffs – the entire Bull Run watershed has been managed under increasing levels of protection since 1892. No public access is allowed in the vast forested area and, according to the Portland Water Bureau, “all land management activities are limited to only those necessary to protect water quality and operate the water supply and hydroelectric power facilities.”

“BullRun has a forest that is more intact, with less overall disturbance, compared with the North Santiam Basin,” says hydrologist Kurt Carpenter of the United States Geological Survey. The land has had – and lost – robust protections since the late 19thcentury, but the last logging there took place in 1993.

The algae buffet; chemicals

Phosphorous and nitrogen “trigger algal blooms,” says Paerl, “because the organisms thrive on high levels of these nutrients.” These chemicals make their way into waters like Detroit Lake, “as either surface runoff from diffuse sources such as agricultural lands [including logged forests] urban storm water runoff, and untreated wastewater inputs from municipalities that do that do not have advanced wastewater treatment facilities,” Paerl says.

Phosphorous pollution has fueled serious algae blooms worldwide, including those that have famously plagued Lake Erie since the mid-1990s. At least thirty-seven long-term, whole lake studies conducted in nine countries in Europe and North America show that controlling phosphorous reduces HABs.

Harmful algae bloom in Lake Erie (Credit: NOAA)

Detroit Reservoir has had relatively high phosphorous levels since at least 1985, Schweickert says. “I don’t know why phosphorous levels are high, but I do know this question needs to be answered. Is it from fertilizer sprayed on young stands of trees (especially private lands that drain directly to the lake)? Is it from runoff from the town of Detroit? Sewage waste? Related to recreational use?”

Heightened levels of phosphorous in Detroit Lake are implicated by all these factors but Carpenter deems that the predominant source is most likely the surface and ground water, and sediment full of nutrients, that wash down through the watershed.

In contrast, Bull Run water “is low in the nutrients that algae need to grow,”says Jaymee Cuti of the Portland Water Bureau. “Bull Run is also protected from public activity, which results in a lack of fertilizers and human sewage sources. This also helps maintain this condition.”


Climate change

All the elements that trigger algae are heightened by a warmer climate and HABs are”quickly becoming a global epidemic,” according to Anna Michalak, at the Carnegie Institution for Science at Stanford. In Blooms like it Hot, published in Science magazine, Paerl and Jef Huisman, Professor of Aquatic Microbial Ecology at the University of Amsterdam, discuss the ways that rising world temperatures appeal to algae, saying, “a link exists between global warming and the worldwide proliferation of harmful cyanobacterial blooms.”

Scientists even suggest that HABs may themselves increase water temperatures, which in turn intensifies the warm conditions that encouraged them in the first place.

Circle of Blue, an organization that reports on worldwide water issues, calls algal blooms “symptoms of a system out of balance” and foresees “a growing water quality crisis that could further deteriorate under climate change.”

Because climate change increases the likelihood of longer wildfire seasons, it also contributes to Detroit Lake algae when wood particles airborne from forest fires drift down and provide nutrients for algae. Hart acknowledges the connection and notes, “There were multiple fires in recent years in the Breitenbush River drainage above Detroit Lake.”


The future of Detroit Lake blooms

A 2016 report by the Environmental Protection Agency and U.S. Geological Survey found HABs in one-third of the 1,161 lakes and reservoirs they studied.

Detroit Lake is now numbered among those waters and City of Salem consultant, Jude Grounds of Carollo Engineers, recognizes the matter, saying, “Algal toxins are an emerging contaminant of concern in the water industry.”

Whether the City has the will – or the authority – to control any of the contributors to HABs before the water reaches Garen Island remains to be seen.

Schweickert, who expresses faith in current City staff, observes that the robust and nuanced watershed protection program developed decades ago by her husband, Public Works director Frank Mauldin along with former Mayors Gertenrich and Swaim, has lapsed in recent years.

“There seems to be a major gap right now,” Schweickert, “because there is no City staff dedicated to a high level watershed protection program. This current crisis highlights the need for that.”