pH Violations in the Lower Deschutes River: Why it’s Happening, and Why it Matters

Round Butte Dam and the Selective Water Withdrawal Tower.

There’s been a great deal of focus on how Selective Water Withdrawal (SWW) operations at Pelton Round Butte have impacted temperatures in the lower Deschutes River. It’s hard not to focus on temperature: it’s something we can easily sense and monitor, and increased spring and summer temperatures have led to some alarming changes in the lower river these last few years.

But to understand the full extent of the ecological changes occurring in the lower river, there’s another criteria that’s perhaps even more important: hydrogen ion concentration, better known as pH. pH levels in the lower Deschutes River have increased dramatically since SWW operations began, and discharges from the Pelton Round Butte complex have routinely violated Oregon’s pH standard. Why is this happening, and how are these increased pH levels impacting the lower Deschutes River?

What is pH?

pH is a numeric scale used to indicate the acidity or basicity of a water-based solution. Pure water is neutral, with a pH of 7 standard units (SU). Solutions with a pH above 7 SU are basic (alkaline), and solutions with a pH below 7 SU are acidic. pH is measured on a logarithmic scale, meaning that a pH of 9 is ten times more alkaline than a pH of 8.

In freshwater systems like the Deschutes River, high pH levels are often the result of increased photosynthetic activity. This is because photosynthesis lowers the dissolved CO2 concentration in the water, which in turn reduces the carbonic acid concentration, which raises pH. As a result, high pH levels are a useful indicator of excessive algal growth and nutrient enrichment in freshwater systems.

Post-SWW Violations of Oregon’s pH Standard

Oregon’s water quality standard for pH in the Deschutes Basin is a minimum of 6.5 and maximum of 8.5 SU. This standard is designed to protect aquatic life from the harmful effects of water that is too acidic or too alkaline. While a pH above 8.5 is not lethal to aquatic life, it does not provide adequate protection; pH levels above 9.0 have been found to cause stress responses in rainbow trout, including sluggish movement, reduced feeding, and ammonia intoxication. High pH also indicates excessive algal growth in the river. The water quality certification for the Pelton Round Butte Complex mandates that discharges from the Project fall within this 6.5-8.5 range, to ensure that Project discharges comply with Oregon’s pH standard and that aquatic life in the lower river is adequately protected.

Since SWW operations began, Project discharges have routinely exceeded the 8.5 maximum standard. In 2016 alone, PGE’s own data show 140 days that pH levels rose above 8.5 at the Reregulating Dam tailrace.

While these numbers are alarming, downstream the problem appears to be even worse. In 2016, the DRA operated a data sonde one mile below the Reregulating Dam, collecting hourly readings for several water quality parameters, including pH, from February through November. Data collected at this site are summarized and analyzed in the DRA’s 2016 Lower Deschutes River Water Quality Report.

The pH data collected at this downstream sampling site are truly concerning. Of the 279 days sampled, 234 days had some pH measurements that exceeded the upper pH standard of 8.5. 120 of these days had pH measurements recorded above 9.0, and pH levels did not drop below 8.5 throughout April, May, and June. pH rose above 9.5 (remember, 10 times more alkaline than a pH of 8.5, and a hundred more times alkaline than a pH of 7.5) on two occasions: July 12 and October 14.

It makes sense that pH levels one mile downstream would be even higher than those in the Reregulating Dam tailrace. Increased algal growth in the river below the Project is increasing the amount of photosynthesis occurring in the river—this increased photosynthesis, in turn, continues to drive up pH levels downstream.

What do These Violations Mean, and Why are They Happening?

These newly elevated pH levels in the lower Deschutes River raise two important questions. First, what do these highly alkaline levels mean for the ecology of the lower river? As indicated above, in freshwater systems high pH levels are a strong indicator of excessive algal growth caused by nutrient enrichment. This will come as no surprise to anyone who has seen (or slipped on) the now-omnipresent nuisance algae blanketing the lower river’s rocks for much of the year. And such a high level of sustained pH poses definite stress and health risks to aquatic life including salmon, steelhead, and resident native trout.

Algae on rocks, one mile below the Pelton Reregulating Dam.

The next question that must be asked is: why is this happening? What is responsible for these elevated levels of pH? The only realistic answer appears to be the commencement of SWW operations.

Before SWW operations began in December 2009, discharges from the Pelton Round Butte Project did exceed Oregon’s pH standard from time to time. But these exceedances were relatively rare: PGE and the Confederated Tribes of Warm Springs, in their 2001 application for the Project’s water quality certification, identified only one instance between 1994 and 1999 where pH below the Reregulating Dam exceeded 8.5. In 2007-2009, the three years immediately before SWW operations began, PGE’s water quality reports show far fewer violations of the 8.5 standard.

Further, Oregon DEQ data collected at the Warm Springs Bridge from 2005-2015 show an immediate and sustained increase in exceedances of the 8.5 standard upon commencement of SWW operations.

Clearly, surface water releases through the SWW tower have had a significant impact on pH levels in the lower Deschutes River. This surface water originates in the Crooked River, the warmest of the three tributaries that enter Lake Billy Chinook, and the tributary with the highest nutrient concentration. As a result, more surface water release means more nutrients are transferred to the lower Deschutes River. This in turn has triggered a significant increase in the growth of periphyton algae in the lower river, which has increased photosynthesis, and pH levels along with it.

The encouraging news about these harmful pH levels is that the solution is right in front of us. To lower pH to levels that are again safe for the river’s aquatic life, the Project operators can significantly increase the percentage of water drawn from the bottom of Lake Billy Chinook. Doing so would slow the Project’s nutrient transfer to the lower river; this would be beneficial not only for pH, but also for the health and diversity of the lower river’s aquatic insect populations and the fish and wildlife that depend on them.

The Pelton Round Butte Project’s current pH violations are at the root of our Clean Water Act lawsuit against Portland General Electric. We’ll be working diligently this year to ensure that these violations—and their resulting ecological impacts—are addressed.

Sources

Wagner, E.J., T. Bosakowski & S. Intelmann (1997). Combined Effects of Temperature and High pH on Mortality and the Stress Response of Rainbow Trout after Stocking. Transactions of the American Fisheries Society. 126:985-998.


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Black Spot Disease in the Lower Deschutes

For anyone who has fished the lower Deschutes River this year, it is not news that many of the fish being caught have Black Spot Disease (BSD). How many fish? We’ve received reports of as many as 100% of 30 fish caught over a three-day trip between Trout Creek and Harpham Flat. Most reports are that 60 to 80% of landed trout have obvious evidence of BSD.

Lower Deschutes River bull trout showing obvious Black Spot Disease. Photo courtesy of Nick Wheeler.

We, along with several of our supporters, have contacted representatives of the Oregon Department of Fish and Wildlife about this issue, and have been told there is nothing to be alarmed about. One of our supporters received an email from ODFW that included the following:

“ODFW has done some research on the effects of blackspot [sic] on spring chinook [sic] smolts in the John Day River and found that the parasite had no adverse effects on condition or survival, even fish that were severely infected performed the same as uninfected fish. Our pathologists also have stated that blackspot [sic] is not categorized as a disease, meaning that it does not appear to effect the host. It is also important to note that blackspot [sic] is very cyclical, and most often comes and goes through time.”

We’ve not seen any research reports from ODFW regarding BSD, although it’s not unusual for these reports to not be advertised or be made readily available. What is unusual is that anglers who fish the bodies of water mentioned by ODFW do not report seeing BSD. This is not to say that BSD isn’t present on the John Day and other rivers, but it’s clearly not present right now to the same extent as in the lower Deschutes.

According to the statement from ODFW, BSD “is not categorized as a disease.” This is a curious claim. Why is it called Black Spot Disease? In all of the scientific literature that we searched, it is always referred to as a disease. This is because infection with BSD results in both systemic inflammation and tissue changes in fish. Inflammation is evidenced by increased cortisol (a hormone associated with stress and inflammation) levels. The skin and scale changes seen on fish with BSD are not caused by trauma. So we have a transmissible infective organism causing inflammation and tissue changes. That meets the definition of a disease.

The fish ODFW representatives have observed with BSD are noted to be in good condition. Yes they are, when they are caught. But no one is performing long-term observation to see what the consequences of chronic infection might be. We are now in the third year of BSD being observed in lower Deschutes River fish, so it’s obvious that more fish are being infected for longer periods of time. None of the studies on BSD to date look at longer-term infections, so those consequences are unknown.

What is known is that fish do die of BSD. According to reports, once fish are infected in the eyes or mouth, survival is limited. And fish with high parasite loads tend to be of lower weight.

The ventral surface of a redband trout with Black Spot disease, caught in the lower Deschutes River in late April 2017. Photo by Jamey Mitchell.

Black spot disease is caused by a flatworm (trematode) parasite known in the scientific community as Uvulifer ambloplitis, and also known as “neascus.” This parasite has a complicated life cycle that starts with eggs in water, which hatch and become juveniles known as miracidia, which in turn infect aquatic snails.  In snails this form of the parasite matures into the next life form, known as cercariae.  Cercariae are shed by the snails and become free swimmers, which attach to fish.  Once the cercariae have attached to the flesh of a fish, the fish develops an immune response that causes the dark spot.

Fish-eating birds are the next host, which become infected when they ingest infected fish.  The cercariae develop into adult flatworms, which means that fish-eating birds are internally infected with the parasite.  The parasite then produces eggs, which are shed in feces by fish-eating birds, and deposited in water where the life cycle is reinitiated.

This summer, many have observed decreases in fish-eating birds in the lowest forty miles of the Deschutes. Kingfishers are rarely seen now in that reach of river (they were previously seen in pairs occupying nearly every reach of river), and merganser populations in the lower forty miles have declined. Are these birds becoming infected with neascus and dying? Or is something else going on? Unfortunately, no one seems to be investigating this phenomenon.

Increases in BSD are associated with increased water temperature and increased aquatic snail populations—both conditions that Selective Water Withdrawal Tower operations have created in the lower Deschutes River. Further, research has demonstrated that rather than being “cyclic,” BSD is linked to sustained elevated water temperatures and algae growth.

The likely solution to reducing BSD is a return to cooler water temperatures and less nutrient loading in the lower Deschutes River. This would require that the SWW tower draw more water from the bottom of Lake Billy Chinook before discharging downstream.

Sources

Schaaf, Cody J, Suzanne J. Kelson, Sébastien C. Nussle, & Stephanie Carlson . Black spot infection in juvenile steelhead trout increases with stream temperature in northern California. Environmental Biology of Fish,; April, 2017.

McAllister, CT, R. Tumlison, H.W. Robison, and S.E. Trauth. An Initial Survey on Black-Spot Disease (Digenea: Strigeoidea: Diplostomidae) in Select Arkansas Fishes. Journal of the Arkansas Academy of Science, Vol. 67, 2013

Schaaf, Cody J. Environmental Factors in Trematode Parasite Dynamics: Water Temperature, Snail Density and Black Spot Disease Parasitism in California Steelhead (Oncorhynchus mykiss). Submitted to University of California Berkley for Masters Thesis, May, 2015.


Deschutes River Alliance: Cooler, cleaner H2O for the lower Deschutes River. 

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