Toxins result in ‘do not drink’ advisory for Salem, the latest U.S. city challenged by cyanobacteria.
By Brett Walton, Circle of Blue
Having detected toxins in its water distribution system since Memorial Day weekend at levels that occasionally exceeded state and federal health guidelines, officials in Salem are warning children, the elderly, and those with liver and kidney disease not to drink the tap water.
A bloom of cyanobacteria, also called blue-green algae for its colorful, scum-like appearance, formed in Detroit Reservoir, the manmade lake on the Santiam River that is the Oregon capital’s drinking water source. Salem Public Works provides water to 192,000 people in the city and surrounding communities.
Algal blooms have occurred in the reservoir in past summers, the time of year when the water temperature is suitable for their growth. But until the last week of May, toxins had never been found in Salem’s water distribution system.
“This is new for us, and we’re adapting as quickly as we can,” Kenny Larson, a city spokesman, told Circle of Blue.
Salem is the latest U.S. municipality to confront a civic disruption caused by cyanobacteria, an increasingly worrisome single-celled, waterborne organism that produces toxins that cause nausea, vomiting, liver damage, and in the worst and rarest case, death. Besides health scares, municipal drinking water warnings send families, businesses, schools, and nursing homes scrambling to acquire bottled water for people and pets, which are also at risk. They also increase the cost of water treatment.
This is new for us, and we’re adapting as quickly as we can.” Kenny Larson, Salem spokesman
Salem officials announced the first drinking water advisory on May 29 for children and vulnerable people — those with liver disease, people on dialysis, people over age 65, and pregnant women. It was lifted on June 2.
The do-not-drink advisory was reinstated on June 6 after treated water samples on June 3 and June 4 tested above health guidelines for vulnerable groups. The new advisory will last for at least two weeks. The city says the water is safe for most people, but keeping the advisory in place is a “precautionary measure.” The latest test results, from June 13, detected toxins but at levels below guidelines for vulnerable groups.
“I would emphasize that the actual likelihood of illness at these levels, even for those groups, is small,” said Richard Leman, chief medical officer at the Oregon Health Authority, at a news conference on June 8. “We are doing this in order to be as cautious as possible in order to protect those folks as we are solving this problem.”
Until the advisory is lifted, residents can get clean water at 11 collection points around the capital region.
Salem Public Works took several actions in response to the toxins. It purchased water sampling equipment that will return quicker results so that workers can shut down the city’s Santiam River intake, located downstream of the reservoir, if toxins are near. To remove toxins already in the system, the public works department is testing the use of powdered activated carbon, a treatment process that would add $2 million per year to the public works budget if it is fully implemented, according to Larson.
The city’s responses are triggered by state and federal health guidelines for cyanotoxins in drinking water. Oregon Health Authority, the state’s public health agency, developed guidelines for four toxins produced by cyanobacteria: anatoxin-a and saxitoxin, which target the nervous system, and cylindrospermopsin and microcystin, two that damage the liver or kidneys. The U.S. Environmental Protection Agency has non-binding guidelines only for the latter two toxins, which are the only two that have been found in Salem’s water above the standards. The EPA guidelines are set at the same level as the state standards.
The guidelines are designed to protect against immediate illness, and are set with a large margin of error, Leman explained. They are calibrated so that individuals should show no ill effects after 10 days of exposure.
Salem started testing water in the Santiam River near its intake for algal toxins in 2011. The tests in May were the first time that toxin levels at that sampling site were above health guidelines. That prompted the city to start testing water in its distribution system as well. It had not done so before May.
An Increase in Harmful Algal Blooms
The dangers of cyanobacteria for drinking water supplies emerged on the national radar when the city of Toledo advised more than 400,000 residents in August 2014 not to drink tap water, a warning that lasted more than two days. A bloom of cyanobacteria in western Lake Erie had entered the city’s water intake.
Federal scientists now monitor algae conditions in Lake Erie and produce weekly forecasts in the summer months. The June 12 forecast anticipates a moderate to severe bloom for the lake’s shallow western basin.
When you don’t know when the problematic organism becomes problematic, it’s hard to understand it.” Kurt Carpenter, U.S. Geological Survey
Geography and land use in central Oregon, however, are far different than on Ohio’s Lake Erie shores, where the size and severity of the bloom is controlled, in large part, by how much phosphorus flows into the lake each spring from farm fields. The outbreak in the Santiam watershed is a reminder that each bloom has its own fingerprint.
Above Detroit Reservoir there is very little agriculture. Eighty percent of the land in the Santiam River watershed, which flows west out of the Cascades Range, is public land managed by the U. S. Forest Service, Bureau of Land Management, or Oregon Department of Forestry. That means few nutrient inputs from farms, septic tanks, or city wastewater plants, which can be contributors.
The causes of the Detroit Reservoir outbreak are still being debated. Kurt Carpenter, a hydrologist with the U.S. Geological Survey’s Oregon Water Science Center, pointed to several lines of inquiry. Carpenter has studied the effect of nutrient enrichment on many of the state’s watersheds.
Cyanobacteria feed on two main nutrients, nitrogen and phosphorus. Dolichospermum, the cyanobacteria colony that are causing problems in Detroit Reservoir, can pull nitrogen from the atmosphere to aid their growth, which gives a competitive advantage over other algae, Carpenter said. The factor that limits growth is phosphorus. In the Santiam watershed, that nutrient comes not from farming but two primary sources: weathering of volcanic rock, which is prevalent in the Cascades and rich in phosphorus, and sediments already washed into the lake bed. Carpenter’s research on other Oregon watersheds found a correlation between upstream logging and phosphorus levels downstream.
Dolichospermum like warm temperatures but not too much sunlight and they can move vertically in the water to find the right conditions. With a low snowpack this year, Carpenter saw water temperatures abnormally high on the Clackamas, a nearby river. But Rick Hargrave, a spokesman for the Portland District of the Army Corps of Engineers, which operates Detroit Reservoir, told Circle of Blue that the corps has not seen a notable change in the reservoir’s temperature this year.
In the Santiam, reservoir operations may also play a role in the outbreak. The Army Corps is under a federal order to manage water temperatures in the river for protected salmon and steelhead fish. Under typical reservoir operations, water is released from the bottom, between 120 and 150 feet deep. But starting in June each year the corps spills water from the top 20 feet to get the right temperature mix for juvenile fish and eggs to survive.
Salem officials asked the corps to delay spilling water, and the corps agreed not to do so until June 21. Larson said that the request was so that the city can test its new treatment equipment under the same water conditions as it has seen in recent weeks — meaning water released from the bottom of the reservoir.
Cyanobacteria do prefer the upper reaches of a reservoir, but Hargrave said he would not speculate about spill resulting in a higher risk of sending toxins downstream. The location of toxins within the reservoir shifts daily, he said.
The movement of toxins is not the only unknown in this case. Carpenter said that knowledge gaps about nutrient inputs and cyanobacteria behavior are substantial. Researchers do not have good numbers on nutrients in rivers like the Santiam that flow westward from the Cascades. They also do not know why some cyanobacteria produce toxins and others do not, even if the cyanobacteria have the genes to do so. Blooms may be large but harmless — or, small but potent.
“When you don’t know when the problematic organism becomes problematic, it’s hard to understand it,” Carpenter said.
Changes in Climate and Testing Requirements
Cyanobacteria have a number of factors working in their favor, and not only in Oregon. A warming climate means warmer water temperatures, which can incubate cyanobacteria, as well as the growth of algae that do not produce toxins. Climate change also means stronger storms, which can flush more nutrients into rivers and lakes.
“Climate change will severely affect our ability to control blooms, and in some cases could make it near impossible,” wrote the aquatic scientists Karl Havens and Hans Paerl, in 2015.
Already there seems to be an increase in blooms in the United States — or, at least an increased awareness. In analyzing news stories, the Environmental Working Group, a research and advocacy organization, found 169 blooms reported last year, up from 51 in 2016 and 15 in 2015.
More data will help, too. Large water systems like Salem are now testing for certain cyanotoxins. This is an EPA requirement under the Safe Drinking Water Act to collect data on how often unregulated contaminants appear in drinking water. The EPA selects up to 30 contaminants per testing cycle.
The 2018 to 2020 cycle requires utilities, for the first time, to monitor 10 cyanotoxins, including six forms of microcystin.
With greater attention comes greater awareness, Carpenter remarked. “We’re probably going to see more toxins as we look more,” he said.