History of Harmful Algal Blooms and Monitoring in Lake Billy Chinook

sww tower

For the fifth summer in a row, the Oregon Health Authority (OHA) issued a Recreational Use Advisory for Lake Billy Chinook (LBC) related to toxin-producing harmful algal blooms, or HABs. Despite this unfortunate anniversary, OHA opted to issue a season-long advisory unrelated to either a specific bloom’s presence or any testing or data that confirms toxic conditions in Lake Billy Chinook. For OHA’s explanation of this new type of advisory, please see its original advisory: https://www.oregon.gov/oha/ERD/Pages/2019-Precautionary-Seasonal-Recreational-Health-Advisory-Lake-Billy-Chinook.aspx.

In the face of annual recurrences, DRA strongly urges OHA to increase monitoring at LBC to better react and respond to the growing problem and to return to bloom-specific advisories that better advise the public of the actual conditions at Lake Billy Chinook.

  • OHA has been aware of Lake Billy Chinook’s toxin-producing harmful algal blooms since at least 2015.
  • The “Precautionary Seasonal Advisory” for LBC this year is not related to either an algae bloom or to toxicity testing results. It is unclear if any HAB monitoring is currently taking place at Lake Billy Chinook.
  • As HAB occurrences increase, more monitoring and testing is needed at LBC to better understand the problem, respond to related environmental issues, and effectively advise recreators.

Since 2004, OHA has issued HAB-related health advisories for Oregon’s freshwater bodies. These alert the public to cyanotoxins’ presence in specific water bodies – a warning to stay out. OHA issues a health advisory when cyanotoxin levels rise above the safe level for recreation. With each advisory, a monitoring, surveillance, and testing program for the specific bloom begins. Once the requisite number of tests return safe levels, OHA lifts the advisory and recreation can safely resume. Even after lifting the advisory, water monitoring samples continues until the bloom is physically gone.

Lake Billy Chinook is no stranger to these HABs or advisories. OHA issued its first advisory for LBC in 2015. Since then, LBC has seen at least one advisory each summer. In the short span of five summers, LBC has shifted from minimally impacted to facing annual blooms.


This year’s Lake Billy Chinook advisory, issued on June 11, stayed in effect until November 1. Dubbed a “Precautionary Seasonal Recreational Use Health Advisory,” this advisory differed from the previous four advisories posted for the Lake and from almost all other HAB advisories throughout Oregon. Except for the South Umpqua River advisory, which is permanently in place, LBC’s season-long advisory is an entirely new approach to warning the public. Rather than providing advisories supported by monitoring and testing data, this new style of advisory only warns of potential HABs throughout the season. Though OHA published “reminders” in July, August, and late September, they only echoed the first warning without offering any new information or data. And despite its own admission in both mid-August and late September that it knows of no toxic HABs in the lake, OHA maintains the advisory.

By issuing a seasonal precautionary advisory, HAB response at Lake Billy Chinook seemed to be in a holding pattern. Without continuous or even intermittent monitoring required, LBC had the ‘potentially unfit for recreation’ status for its entire summer recreation period. Despite the increasing frequency, OHA’s choice to issue the seasonal advisory results in almost no monitoring. Because an advisory is already in place, no bloom monitoring or testing is required to confirm the need for an advisory. Likewise, with the advisory in place until November 1, presumably no testing to track a bloom or to lift the advisory took place. Instead, Lake Billy Chinook sat by idly, recreation restricted, blooms untested, the problem largely unaddressed – with the public left wondering whether the water was actually toxic or not.

OHA’s lackluster response to the growing HAB problem at Lake Billy Chinook has serious repercussions. The first of these is to recreation at LBC. Without specific information, tourists and recreators could have relied on this advisory and foregone recreation at LBC altogether, with potentially significant impacts on the local economy. With many other recreation locations in Oregon, tourists could easily move their plans, and their business, elsewhere. All this because of the seasonal advisory that was not supported by data and without actual knowledge of a HAB in LBC.

In addition to the recreational and local economic impacts, OHA risks losing any meaning behind their HAB advisory. If OHA issues seasonal advisories as a matter of form without any supporting evidence, it will lose its significance to the public. This could lead both tourists and locals to either ignore the warning (and risk using what in fact are the actually dangerous waters) or to leave LBC behind (when in fact the danger has passed) in favor of other water bodies. Both are bad options. And both can be avoided by returning to the previous method of monitoring and advising. Already in this first year, the advisory seemed to be ineffective. Between the lack of signage, lack of clarity in the warning, and ineffective communication, many recreators were unaware of LBC’s advisory status over the Labor Day weekend. There really is no other reasonable policy option: OHA should abandon the seasonal advisory approach in order to protect the public.

While this post has focused on Lake Billy Chinook, the impacts reach beyond its boundaries. As the upstream source of water for the lower Deschutes River, the HABs in LBC are passed through the Selective Water Withdraw Tower at the Round Butte Dam. As noted in our previous reports, the lower Deschutes River already faces detrimental effects from the surface water release from Lake Billy Chinook. Migrating salmon and trout, along with downstream users, face yet another hurdle from these toxic blooms. HAB monitoring in Lake Billy Chinook, therefore, is needed for multiple reasons. Actual timely data about the blooms, and the presence of cyanotoxin, will help us understand the scope of the problem, provide more accurate warnings to protect human health, and encourage reasonable action in the public interest.

A Small Parasite is Likely Killing Deschutes River Spring Chinook

The Deschutes River population of wild spring Chinook salmon is in trouble. A pre-season run forecast by the Confederated Tribes of the Warm Springs Reservation (CTWS) and the U.S. Fish and Wildlife Service predicts that in 2018, only between 127 and 448 adult wild spring Chinook will return to the Deschutes River to spawn in the Warm Springs River.

This predicted return is considerably lower than the average return over the last 10 years of 685 wild fish, which itself is only around half of the optimum escapement goal for the run (identified in Oregon’s Administrative Rules as 1,300 fish per year). As an organization concerned with the health and abundance of all wild fishes in the Deschutes River, DRA finds this prediction very alarming, and is focused on understanding why this decline is happening and what can be done to reverse it.

As with other wild salmon runs in the Pacific Northwest, there are several possible explanations for the decline of Deschutes River wild spring Chinook. But there is one very likely culprit that DRA feels is being ignored. In recent years, there has been a dramatic increase in the lower Deschutes River of the parasite Ceratonova shasta. This salmon-killing parasite, historically not a significant mortality factor in the lower river, is now abundant, and is having demonstrable impacts on spring Chinook. Recent studies and observations show that it is infecting and killing juvenile Chinook in the lower Deschutes, and may also be responsible for high pre-spawning mortality of adult spring Chinook. This rise in Ceratonova shasta is likely causing significant harm to the already fragile wild spring Chinook population, and also jeopardizing efforts to reintroduce spring Chinook above the Pelton Round Butte Hydroelectric Project, as those reintroduced juveniles and adults must migrate through the Deschutes River’s lower 100 miles on their journey to and from the ocean.

Why is this happening now? What more can be done to protect this important and fragile population of wild spring Chinook salmon?

Lower Deschutes River Chinook salmon. Photo by Brian O’Keefe.

Ceratonova Shasta in the Lower Deschutes River

            To understand why this parasite is so prevalent now, some background on the organism and its life cycle is important. Ceratonova shasta (or C. shasta), which is microscopic in size, is present in many Pacific Northwest streams and can be lethal to some salmonids, including Chinook salmon. It has been extensively studied for many years, and some of the original life history research on the parasite’s life cycle was done in the Deschutes River system. C. shasta has an interesting life cycle in which a small polychaete worm, Manayunkia speciosa, serves as an intermediate host which sheds the infective C. shasta organism into the water. This stage of the organism, the actinospore, then infects a fish, and the parasitic infection can be lethal from harm to the kidney and digestive system.

Life cycle of Ceratonova Shasta. Source: Oregon State University, http://microbiology.science.oregonstate.edu/deschutes-river

Historically, C. shasta has been more prevalent in warmer southern Oregon rivers, and was not thought to be a significant problem in the lower Deschutes. Unfortunately, this no longer appears to be the case. According to the U.S. Fish and Wildlife Service, in 2014 staff at the Warm Springs National Fish Hatchery observed returning adult spring Chinook infected with C. shasta. Additional studies found that both juvenile and adult Deschutes River Chinook were dying prematurely, with C. shasta the suspected cause. And a recent study in the lower Deschutes River demonstrated unusually high levels of C. shasta spores in the water, as well as high levels of C. shasta-related mortality in caged spring Chinook juveniles. Disturbingly, in a sampling site located near Oak Springs Hatchery (located just downstream from Maupin) as many as 87% of caged juvenile Chinook were infected with C. shasta after being exposed to Deschutes River water for 72 hours.

Why Now?

            Various explanations have been offered for the increased presence of C. shasta in the lower river, including increases in water temperature due to climate change. However, DRA believes there is a more fundamental explanation for the marked increase in the C. shasta parasite documented these last few years—an explanation we have not yet seen in discussions around the topic.

Based on available information and data, it appears that the increase in C. shasta may be directly related to operations at the Selective Water Withdrawal (SWW) tower above Round Butte Dam. Since SWW operations began in late 2009, water quality on the lower Deschutes has declined—largely due to the warmer and nutrient-rich surface water from Lake Billy Chinook that is being passed downstream into the lower river. This abrupt change in water quality has also changed the macroinvertebrate community below the Pelton Round Butte project. This has included significant increases in non-insect taxa, including in the presence of Manayunkia speciosa—the polychaete worm that serves as the intermediate host for the C. shasta parasite. While pre-tower sampling in the lower Deschutes did not collect any M. speciosa, post-tower studies in the same locations have collected as many as several thousand M. speciosa individuals per square meter of stream bottom. Similarly, DRA post-tower sampling efforts have collected as many as 8,285 M. speciosa per square meter at Dizney Riffle.

This dramatic increase in M. speciosa is likely a significant factor, if not the driving factor, in the new and increased prevalence of the C. shasta parasite, and the subsequent harm that is resulting to the Deschutes River spring Chinook population. This hypothesis is supported by CTWS data showing a dramatic increase, since 2010, in the percentage of adult spring Chinook that are being counted at Warm Springs National Fish Hatchery and passed upstream, but then dying before they are able to spawn. The chart below reflects data collected on wild spring Chinook in the Warm Springs River from 1977-2016. The chart shows the number of wild fish counted at Warm Springs National Fish Hatchery, divided by the number of Chinook redds counted in spawning ground counts later in the year. (“fish per redd”). A larger number of fish per redd means that more fish died after they were counted at the hatchery and released upstream to spawn naturally, but before those fish were able to spawn.

Fish per redd in WSR basin, 1977 – 2016. From Confederated Tribes of the Warm Springs Reservation of Oregon Natural Production Monitoring Progress Report, January 1, 2015 to December 31, 2016. BPA Project # 2008-311-00, BPA contracts #: 64276, 69558, 73078. Authors: Graham Boostrom and Cyndi Baker.

As you can see, the average number of “fish per redd” in the Warm Springs River jumped from 4.0 from 1977-2009, to 13.1 from 2010-2016. (Further, an astounding 19 adult spring chinook were required to result in one redd in 2016, and 24 adults were required in 2017). In other words, there has been a marked increase in pre-spawning mortality since 2010, which coincides with the commencement of SWW operations in late 2009. These pre-spawning deaths could very well be attributable to Chinook adults being infected by C. shasta on their trip up the Deschutes mainstem.

In sum: The increased presence of C. shasta in the Deschutes River is likely due in significant part to marked increases in the parasite’s intermediate host in the lower river, which in turn is likely due to changes in water quality resulting from SWW operations. And the C. shasta parasite is having a very real impact on spring Chinook salmon in the Deschutes River: it is clearly killing juveniles, and is very likely infecting and killing pre-spawning adults as well.

Deschutes River Spring Chinook Need Help

            More information is needed on C. shasta’s present impacts on Chinook salmon in the Deschutes basin. And it is imperative that basin stakeholders take a hard look at the role of SWW operations in the rise of this fish-killing parasite. C. shasta is not just impacting the threatened wild population of Deschutes River spring Chinook: it is likely playing a role in the extremely low numbers of spring Chinook returning to the Pelton Round Butte Project as part of fish reintroduction efforts there. We call on the agencies responsible for the management of this wild run of spring Chinook to acknowledge these impacts, study the situation, and take aggressive action to stop the loss of these fish before it’s too late. The present decline in wild spring Chinook numbers would predict an extinction event unless such aggressive action is taken. It is time to stop blaming ocean conditions and climate change for this problem, and acknowledge that there are immediate actions we can take that would likely reverse the decline of this treasured wild run.

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

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Announcing the DRA 2016-2017 Macroinvertebrate Hatch Survey Report

Photo by Rick Hafele

The Deschutes River Alliance is pleased to present its 2016-2017 Macroinvertebrate Hatch Survey Report, prepared by Rick Hafele. As in previous years, this report describes survey data collected by lower Deschutes River fishing guides, documenting the presence and abundance of the major adult aquatic insect hatches on the lower river.

The survey data compiled in the DRA Hatch Survey Reports represent a systematic attempt to document changes in adult insect emergence timing and abundance on the lower Deschutes River. This data, submitted by highly experienced guides, provides the only ongoing assessment of changes to the lower river’s aquatic insect populations.

Here are some of the key takeaways from this year’s survey results and analysis:

  • As in previous years, survey results show that adult abundance of the four major orders of aquatic insects—mayflies, stoneflies, caddisflies, and Diptera (chironomids and crane flies)—is low from spring through fall. Percent of observations with high numbers of adults is rarely above 10% of all observations.
  • Emergence of all major hatches are occurring four to six weeks earlier than they did prior to the commencement of surface water withdrawal operations at Round Butte Dam.
  • The earlier emergence of these hatches is creating a period in the spring (typically early April through late May) when the vast majority of insect hatches now occur. After early- to mid-June insect hatches become scarce and unpredictable.
  • Many river users have reported that wildlife along the lower Deschutes River corridor that depend on aquatic insect adults (e.g. swallows, bats, nighthawks, and song birds) continue to show depressed numbers. This is mostly likely due to a lack of available food.

DRA believes that the above changes in adult insect timing and abundance can be directly linked to the changes in water quality—including higher nutrient loads and warmer water temperatures in the spring and early summer—resulting from selective water withdrawal operations at Round Butte Dam. The survey data summarized in this year’s report, along with reports from previous years, provide key information needed to fully understand the impact of recent changes in the lower Deschutes River.

Read the full report here.

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New Analysis Shows Significant Ecological Decline in Lower Deschutes River After Commencement of Selective Water Withdrawal Operations

Photo by Brian O’Keefe

In the years since Selective Water Withdrawal (SWW) operations began at the Pelton Round Butte Complex, longtime Deschutes River users have observed and reported what appear to be major ecological changes below the dams. A new report confirms these observations. A new analysis by Portland State University Assistant Professor Patrick Edwards, Ph.D., establishes that the macroinvertebrate community in the lower Deschutes River has significantly changed since surface water from Lake Billy Chinook began to be released through the SWW tower downstream into the lower river. According to Professor Edwards’ analysis, the post-SWW community contains “more non-insect taxa, such as worms and snails, and other taxa that are tolerant to poor stream conditions.” Further, there are now fewer “mayfly, stonefly and caddisfly taxa that are sensitive to poor stream conditions.”

Some background on Dr. Edwards’ study is useful. In April 2016, R2 Resource Consultants, a company under contract to Portland General Electric, released a Lower Deschutes River Macroinvertebrate and Periphyton Study. This was a four-year study, mandated by the Pelton Round Butte Project’s Clean Water Act certification, that aimed to compare post-SWW conditions in the lower Deschutes River to pre-SWW conditions that were documented in a baseline study.

Round Butte Dam and the Selective Water Withdrawal Tower.

The conclusions in the R2 study were perplexing. Among other findings, the authors stated that “[s]tudy results did not identify large changes in the macroinvertebrate community before and after SWW implementation.” The DRA Science Team, which had been following the development of this study closely, identified several problems with the final report, and in the following weeks worked with several outside experts to assess the data analysis and statistical methods used in the study.

Then, a few weeks after the R2 report was issued, the Oregon Department of Environmental Quality (ODEQ) stepped in. In a letter to PGE, ODEQ deemed the R2 report inadequate and deficient in several key components, and requested that PGE provide a response to correct the “serious shortcomings” in its analysis.

PGE responded to the ODEQ letter by stating that it would address the agency’s concerns and would summarize this additional work in an addendum to the original report—a process PGE estimated would take 6-12 months to complete. It now has been 19 months since that response letter was sent, and the promised addendum still has not issued.

In the same letter, PGE stated that despite its shortcomings, the initial report—which had already been submitted to the Federal Energy Regulatory Commission (FERC) —satisfied PGE’s obligations under the FERC license for macroinvertebrate monitoring. In other words, PGE claimed it had met its requirements with a report that ODEQ had identified as deficient in several respects.

We at the DRA felt it was essential that an accurate analysis of the pre- and post-SWW macroinvertebrate data be completed as quickly as possible. To that end, we contracted with Dr. Edwards to perform a thorough and accurate statistical analysis of the same data used in the R2 report. Dr. Edwards is highly qualified to perform this analysis, as his PhD in environmental science included extensive use of multivariate statistic—an analytical technique commonly used to assess changes in macroinvertebrate communities. The purpose of Dr. Edwards’ analysis was to assess the characteristics of the macroinvertebrate community pre- and post-SWW.

Photo by Brian O’Keefe.

The results of Dr. Edwards’ analysis are truly concerning. Data collected in the springtime showed that the post-SWW community has significantly fewer mayflies, stoneflies, and caddisflies—all species that are more sensitive to poor stream conditions. Data from both the spring and fall seasons showed an increase in taxa that are more tolerant to poor stream conditions, including worms and snails.

As a result of Dr. Edwards’ analysis, there is sound science confirming what many have suspected for years: SWW operations are significantly altering the ecology of the lower Deschutes River. The discharge of surface water from Lake Billy Chinook has caused serious, negative impacts to water quality in the lower river, and those impacts are leading to significant changes in the insect community below the dam complex. Negative changes to aquatic insects are a serious concern, as they support the entire food chain within the river, particularly resident trout, juvenile salmon and steelhead, and wildlife along the river – including birds and bats. Sound science establishes that these changes are statistically significant. DRA believes strongly that these changes can and must be reversed.

Presumably, if PGE’s initial analysis of this data had been sound, efforts in the intervening months and years could have been focused on addressing the ecological decline in the lower river. We certainly hope that work will commence, at long last, but we are proceeding with legal action to ensure no further delay.

For more information about Dr. Edwards’ analysis, read Rick Hafele’s summary of the report here.

To read the full report, click here.

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An Overview of Dr. Edwards’ Aquatic Invertebrate Study Analysis

By Rick Hafele

As recently reported, the DRA has just posted to its website a new report, by Dr. Patrick Edwards, that provides a detailed statistical analysis of the aquatic macroinvertebrates in the Deschutes River before and after the commencement of surface water releases from the Selective Water Withdrawal (SWW) tower at Round Butte Dam. Dr. Edwards’ report provides important confirmation that since the SWW Tower began operating, aquatic life in the lower Deschutes River (the 100 miles of river below the dams) has changed significantly for the worse.

Dr. Edwards’ report is actually a new analysis of data originally collected and analyzed for PGE by R2 Resource Consultants, as required under the Pelton Round Butte Project’s Clean Water Act certification. The R2 report and data were released to the public in April 2016. Unfortunately R2’s original analysis was flawed. As a result, the Oregon Department of Environmental Quality (ODEQ) requested that PGE have the data reanalyzed using proper methods. It has now been 19 months since that request by ODEQ, and PGE has yet to release a new analysis of the study.

To ensure that a new unbiased analysis would be completed, the DRA commissioned Dr. Edwards to reanalyze the data from the R2 study. To further ensure that the methods used by Dr. Edwards were correct and based on the best available statistical methods, the DRA had the report peer reviewed by one of the top environmental statisticians in the country.

While we invite all of our supporters to read the lower Deschutes River aquatic macroinvertebrate report by Dr. Edwards, the analysis relies on a number of complex statistical methods; unless you have a degree in statistics, it might leave you scratching your head. For that reason a less technical explanation of the analysis and its findings is provided here.

Photo by Rick Hafele

Why Aquatic Invertebrates and Algae?

            You might first wonder why aquatic macroinvertebrates (this includes all aquatic insects, as well as other invertebrates like snails and worms) and algae were the only aquatic life forms sampled to assess the possible impacts of surface water withdrawal on the ecology of the lower Deschutes River. Aren’t trout, steelhead, and salmon much more important as a recreational resource and commercial commodity? Certainly, fish outweigh invertebrates and algae in recreational and economic importance, but in terms of ecosystem health, if the organisms at the bottom of the food chain aren’t healthy and sustainable then the rest of the species further up the food chain will suffer.

There are several reasons why these lower food chain communities, especially aquatic invertebrates, are often closely examined in stream health studies.

  1. Aquatic invertebrates can be sampled more effectively and at less cost than fish. This is particularly true in a big river like the lower Deschutes. This doesn’t mean that fish studies in the lower Deschutes aren’t possible or shouldn’t be done but, to get a relatively quick and accurate assessment of possible impacts to the aquatic ecosystem, aquatic invertebrates are a good choice.
  2. Because the life cycle of aquatic invertebrates is much shorter than fish (one year or less for most invertebrates compared to four to six years for most salmonids) they will show a response to environmental changes much faster than will fish. This is critical if one wants to identify ecosystem problems as soon as possible.
  3. There is a long history within the study of stream ecology of sampling aquatic invertebrate populations to assess stream health and function. This means there are well-established methods for sampling and analyzing the data, and for interpreting the results. For example, when certain invertebrate populations thrive while others are lost or diminished, prior experience on other rivers can help us understand what is happening on the lower Deschutes.
  4. Last, the number of species of aquatic invertebrates found in Western rivers and streams is much greater than the diversity of fish, giving researchers a broader, more robust community of organisms to study. For example, invertebrate studies often collect more than 100 different species from a single Western stream, compared to 3-6 species of fish. In addition, the sensitivity of these different invertebrates to altered water quality and habitat conditions have been well documented for a wide range of species, and the sensitivity of different species to changes in water quality varies over a wide range. As a result, changes in the species composition of invertebrates provide a sensitive indicator of impacts to the biological health of streams and rivers. For example, decades of studies have shown that stoneflies are more sensitive to poor water quality than most other species. Therefore, a decline in their diversity or abundance is one of the first signs of declining stream health.

Photo by Rick Hafele.

Statistical Methods Used

            The purpose of Dr. Edwards’ study was to determine if the aquatic invertebrate community sampled after surface withdrawal began had changed in a statistically significant way from the community present before surface withdrawal. To make this determination, Dr. Edwards used three statistical methods:

  1. Multivariate ordinations
  2. A measure of species diversity
  3. A measure of species pollution tolerance

Multivariate ordinations:

Multivariate statistics is a powerful tool that you won’t find discussed in Statistics 101. This powerful and complex field of statistical analysis requires considerable experience to use and understand. Multivariate statistical methods like Non-metric Multi Dimensional Scaling (NMDS) are commonly used today partly because modern computing power makes it possible.

Basically, NMDS takes all 100+ invertebrate taxa from each sample and plots the relative abundance of each taxon in each sample in multidimensional space, and then compresses the multiple dimensions into a two-dimensional graph. The distance between dots on the plot indicate their degree of similarity; dots close together indicates a similar invertebrate community between samples, while dots farther apart indicates the communities present were different. Whether the distance between two groups of dots is statistically significant (meaning that the difference noted is very likely the result of actual differences and not due to random chance alone) is determined by performing other statistical tests.

The results of this analysis comparing the pre-tower to post-tower samples from the lower Deschutes River, showed that a statistically significant change occurred to the invertebrate community from the pre-tower to post-tower periods. What kind of change occurred is addressed with the other two analyses discussed below.

Measure of species diversity:

One of the most common measures of ecological or biological health is the diversity of species present. Healthy ecosystems are diverse ecosystems. In stream studies, healthier stream conditions are indicated by invertebrate communities with more species that are sensitive to poor water quality (higher temperature, lower dissolved oxygen or nutrient enrichment), relative to the number of species that are more tolerant of poor stream conditions. Mayflies, stoneflies, and caddisflies are the three groups of aquatic invertebrates with the most sensitive species to poor water quality. A decline in these sensitive species relative to species known to be more tolerant of degraded water is a sign that water quality is becoming degraded and constraining aquatic invertebrate populations. The metric EPTr refers to the percent of species of mayflies (E), stoneflies (P) and caddisflies (T) relative to the number of other species in the sample. In this study the metric EPTr was used to assess changes in the diversity of the sensitive taxa. The results show that at sites in the lower Deschutes River, EPTr declined in post-tower samples from pre-tower samples in both the spring and fall, and that the decline was statistically significant in the spring samples. A similar statistically significant decline was not observed at the three sites above the Round-Butte Dam Complex.

Measure of pollution tolerance:

As mentioned above, different species of aquatic invertebrates have different tolerance levels to water pollution. Years of researching the sensitivity of individual taxa to water quality conditions has produced a set of “tolerance” scores for each taxa. The metric used in this study is called RICHTOL, which calculates the mean tolerance score of all taxa present in a sample. Tolerance scores for individual taxa range from 0 to 10, with lower scores indicating more sensitivity to polluted water—species with these lower scores are more likely to decline in abundance as water quality declines. This analysis shows a statistically significant increase in the RICHTOL score in post-tower samples compared to pre-tower samples below the dam complex during both the spring and fall sample periods. An increase of this score indicates an increase in taxa present with greater tolerance to poor water quality, strongly suggesting that water quality has declined and this decline is having a negative affect on the aquatic invertebrate community. Again the sites above the dam complex did not show a similar significant increase in tolerant taxa.

Round Butte Dam and the Selective Water Withdrawal Tower.


  In summary, here are the principal findings from Dr. Edwards’ statistical analysis:

  1. A multivariate statistical analysis, comparing the complete invertebrate community in the lower Deschutes River from before tower operations to after tower operations, found that a statistically significant change in the community occurred.
  2. Comparing pre-tower samples to post-tower samples showed that a decline in the percent of sensitive species of mayflies, stoneflies, and caddisflies occurred at sites in the lower Deschutes River.
  3. A comparison of pre-tower to post-tower samples also found that taxa tolerant to poor water quality conditions increased significantly at sites in the lower Deschutes River below the dams, but no significant increase occurred at sites above the dams.

These results confirm: 1) a significant change has occurred to the macroinvertebrate community in the lower Deschutes River after tower operations and surface water releases began, and 2) a significant decline in pollution sensitive species (mayflies, stoneflies and caddisflies) and a significant increase in pollution tolerant species (primarily worms and snails) has occurred in the lower Deschutes River following surface water releases at the SWW tower.

Decades of stream studies have documented similar impacts due to nutrient enrichment and the resulting changes in water chemistry and algal communities. For example, as long ago as the early 1970s stream ecologists understood that large dams and reservoirs can impact waters downstream, as shown in the following quote from the seminal book on stream ecology, The Ecology of Running Waters, by H.B.N. Hynes:

The great photosynthetic activity in large impoundments has marked effects upon the chemistry of the water, raising pH and oxygen content and reducing the hardness of the water. The influence of a large dam is therefore profound and it extends a long way downstream.

             Anyone who has spent time on the lower Deschutes River after the SWW tower began operating knows there have been negative changes to water quality and the aquatic community. For example, if you have a house on the river, the simple fact that you no longer have to close your door at night to keep the bugs out when a porch light is on is a clear signal that something isn’t right. Observant anglers have seen crane fly numbers fall from very abundant to nearly non-existent. So why worry about statistics? Unfortunately those who might disagree with your porch light results or your onstream information on insect life may argue that your observations are anecdotal and don’t “prove” there is a biological impact from SWW operation. Such “proof” can be elusive, which is where the use of statistical analysis becomes important. The use of advanced statistical methods sets a standard for the level of confidence that the observed changes are real and not due to random variation.

Dr. Edwards’ analysis confirms what river users have been observing since the SWW tower began operating – the health of the river has declined. Fortunately, we know there is a simple way to reverse this decline in the river’s biological health: a significant increase in the amount of cooler, cleaner water discharged from the bottom of Lake Billy Chinook into the lower river.

For an introduction to Dr. Edwards’ report, click here.

To read the full report, click here:

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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.


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.


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.

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