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It’s quiet and calm in the morning sunlight as EWEB Senior Environmental Specialist David Donahue pushes through some scotch broom to get to his water quality sampling site alongside Gate Creek. The trees above him bear scars from the Holiday Farm Fire. Standing on a rock near a U.S. Geological Survey (USGS) monitoring station, he attaches a sample bottle to a long pole to collect some water from the creek. 

A Bald Eagle lands on a burned fir across the creek. 

Donahue pauses to appreciate the on-looker. He pours the water into smaller bottles, labels them with the date and location, and then collects a concentrated algae sample with a 70-micron plankton net tow. The eagle flies away. Donahue heads to his truck to place his samples in a cooler. 

Then it’s on to the next site.

A visit from the eagle is special – but it’s all part of the routine for Donahue, who has been collecting water quality samples for EWEB for the past 17 years. His work is part of EWEB’s commitment to monitoring the health of the McKenzie River – the sole source of drinking water for 200,000 people in the Eugene area.  

“Coming out here to collect samples is part of our early warning system and helps us communicate with the water treatment operators,” he says. “We can see what’s going on upriver and give them a heads up that, for example, we might have a potentially concerning algal bloom happening.” 

EWEB keeps a watchful eye on the watershed. Donahue’s visits are like a physician assessing a patient – he goes out to look around, smell, touch. He uses his senses to make sure nothing is off. Complimenting his visits is an automated network of sensors – the smart watch in our patient analogy. EWEB partners with the USGS to operate eight water quality stations that continuously collect data throughout the watershed. These stations track water temperature, turbidity (how cloudy or clear the water is), electrical conductivity (indicating the concentration of dissolved ions), fluorescent dissolved organic matter (corresponding to total organic carbon), pH, dissolved oxygen, and a total algae sensor that can detect pigments in phytoplankton.

Below a swarm of swallows at the base of Cougar Dam, Donahue places a similar multi-parameter water quality sonde into the reservoir.  

“This is the same type of equipment or sonde that we have continuously monitoring river conditions and other tributaries throughout the McKenzie Watershed. The data across sites is easier to evaluate because the equipment is similar,” he says. “Not only can we compare continuous reads throughout the year across sites, but we can also compare those measurements with the discrete sampling results. If something seems out of place or maybe we have a question with the analytical results, we can go back to the continuous water quality data and figure out if there are clues within the physical conditions of the water body at the time of sampling that would help us better understand the analytical results.” 

He dips the plankton net tow and swishes it through the water several times, concentrating any algae in the water column in front of him. EWEB begins monitoring for algae in March or April, depending on spring conditions.  

In the McKenzie Watershed, cyanobacteria blooms that may contain potentially harmful toxins typically appear in the spring or early summer, if at all, but that can certainly change from year to year depending on multiple factors.  

“In our watershed we can see blooms forming in the Army Corps reservoirs – Cougar Reservoir, Blue River Reservoir – as early as April.  These blooms can become relatively concentrated within a matter of weeks,” he explains.

Donahue collects his samples then heads below Cougar Dam to his sampling spot along the South Fork McKenzie River. He drives north to the Blue River Reservoir. At Lookout Campground, a Stellar’s Jay imitates a Red-tailed Hawk.

Donahue points to the shoreline where a concentration of suspended material that looks like pollen is floating among the grasses. It reminds Donahue of how EWEB’s cyanobacteria monitoring program began.  

“In 2010 we got a call from the USDA Forest Service about a potential water quality concern they observed in Blue River Reservoir. When we arrived, we noticed a fairly concentrated bloom occurring that looked similar to pollen grains,” he says.  

“We weren’t sure what it was at first. We collected a sample, sent it off, and it was Gloeotrichia (pronounced “glee-oh-tricky-ah). A relatively harmless cyanobacteria, at least in the Pacific Northwest, so far as we can tell. That motivated us to look more thoughtfully at these reservoirs in 2010 to see what was going on from a phytoplankton standpoint. We wondered if there were other cyanobacteria populations in these reservoirs that we should be concerned about, especially since some species can produce cyanotoxins. 

“We started doing more monitoring the following year. These days, we typically sample every two weeks from April through October looking for potential cyanotoxin production.”

At Blue River Reservoir, winds can push surface-dwelling algae species to concentrate in different areas, particularly along the northeast side. It can be problematic, as that’s also where the boat ramp and campgrounds are.  

“Some of the highest concentrations of suspended cyanobacteria I've observed have been at this reservoir on the east end – including the occasional toxin detection. So far, all toxin detections have been well below the State’s recreational use values. But this area also coincides with campgrounds locations and where a lot of people recreate. Not only does our monitoring help inform our drinking water treatment plant operations further downstream, but we'll also share this information with the USDA Forest Service and others who oversee the campgrounds.” 

Sampling phytoplankton in reservoirs can be challenging. Some phytoplankton species stay near the surface where winds can move them around easily. Others move up and down in the water column and currents can push them towards the dam. 

A family of Canada Geese parade by as Donahue takes his final sample of the day on Blue River, near to its confluence with the McKenzie. He dips, nets, bottles, and heads back to EWEB’s Water Quality Lab to process his samples.

Lisa Erkert, another Environmental Specialist with EWEB’s Source Protection Program, has spent the day collecting algae samples at other sites. Erkert ships samples off to a lab in Ohio for algal identification and to another lab in California for qPCR genetic testing to identify biomarkers for genes responsible for producing toxins. 

“We are fortunate to have in-house toxin testing capabilities, which goes hand in hand with the qPCR genetic testing and the algae ID and enumeration," Donahue explains. “All three together give us a really clear idea of what's happening in these large reservoirs in our watershed, upstream of our intake.  

“In the event that we do detect toxin-producing genes or toxins in the reservoirs, we can increase our frequency of sampling. We're also monitoring downstream of these reservoirs to get a sense if toxins in the reservoirs are making it to the mainstem McKenzie, and to confirm that toxins aren’t making it all the way down to our intake.” 

Over the past five years there have been no toxin detections at EWEB’s drinking water intake in Springfield. Should toxins make it all the way downstream, EWEB’s Treatment Plant Operators can handle the challenge.  

“Powdered activated carbon (PAC) can be used as a treatment method to reduce and/or potentially eliminate algal toxins in drinking water process,” says Hayden Bridge Water Treatment Plant Supervisor Toby Dixon. “Recent upgrades to Hayden Bridge’s PAC system have created process resiliency and safety for the operators.” 

“Lastly, we do collect another set of samples for our in-house lab to test for nutrients,” Donahue continues. “We test for nitrate, phosphorus, orthophosphate, and carbon – total organic carbon and dissolved organic carbon. We try to understand what the nutrient levels are when we're collecting algae samples so we can get a better sense of what might be influencing bloom development.” 

After shipping and processing the samples, Donahue uses a pipette to add a small drop of a concentrated sample onto a slide for his microscope. No birds look over his shoulders for this part; just a watercolor orca and chameleon painted by his kids. 

“I usually start out at a much lower magnification and scan the slide for anything that stands out,” he says, eagerly looking into his microscope. This could be the presence or dominance of familiar cyanobacteria taxa, or perhaps something new that he hasn’t observed before. 

While he observes general seasonal patterns in cyanobacterial blooms, toxin production within these blooms is much more difficult to predict. We still have much to learn about how these cyanobacteria communities interact and adapt within the watershed, and what environmental drivers might favor populations that are more toxigenic. 

Over the past 15 years, Donahue has learned quite a bit, though.

“There's a little amoeba floating around my field of view. If I go to a slightly higher magnification and turn up the light, we can see it next to the measurement bar, and it’s about 20 micrometers, a nice sized amoeba. The treatment plant neutralizes microorganisms, such as amoebas, during the drinking water treatment process, so I'm not too concerned about finding the occasional amoeba. It’s a sign of a diverse and healthy ecosystem," he says. 

Donahue moves on to find a filament of cyanobacteria in the sample. Finding cyanobacteria in a slide is very common and doesn’t necessarily mean there are cyanotoxins. 

“I’m unable to tell if this filament can produce cyanotoxins using just a microscope. I can identify, however, that this is a filament of Oscillatoria and some members of this genus can produce toxins. Zooming in, you can see this filament looks like a series of stacked little buttons.” 

Donahue identifies the filament as likely Oscillatoria princeps, which is typically a benthic organism. “That means it's very adept at growing along the bottom of creeks, streams, ponds, or anything floating. We just happened to catch one of these filaments that was passing by in the water column when we did our net tow,” he explains. 

Donahue pulls up another slide and finds Dolichospermum, a green, spaghetti-like chain of translucent meatballs.

“That was collected from Blue River Reservoir. Dolichospermum is the genus of cyanobacteria that we pay the most attention to in the McKenzie watershed, since some species within the genus are likely capable of producing toxins in our reservoirs.  

Dolichospermum chains are made of three cell types. The smaller, vegetative cells can reproduce and are responsible for photosynthesis. The round, clear heterocysts can fix nitrogen.  

“One of the neat things about cyanobacteria and why they're so adaptive is, even if nitrogen levels are pretty low in the water column, they're able to fix atmospheric nitrogen with their specialized heterocysts cells,” Donahue points out. 

“Here’s an example of a much larger cell which is called an akinete. We don’t see these as often, at least not typically until the late stages of a bloom cycle, and their purpose is to provide an overwintering cell for this particular species. From the akinete, it can germinate additional vegetative cells during the next bloom cycle.  

“The position of the akinete along with the heterocyst and the vegetative cells can help inform you about what species of cyanobacteria you're looking at. It is impossible to tell from looking at a slide, though, if a species is toxic. For the next step of analysis, once we identify that we've got Dolichospermum in the system, the samples are sent for cyanotoxin analysis, which we do in-house. Being able to process these samples at our own lab let’s us get results quickly to support our source protection work." 

Donahue identifies multiple other phytoplankton and critters. Zooplankton dance in a vial. The pollen-sized Gloeotrichia look like a giant spiny urchin under magnification.  

Donahue peers through his microscope, continues wading through the microcosmos. His mission: a never-ending search to be as sure as possible, that he keeps a close eye on the source for Eugene’s drinking water.