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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Announcing the DRA’s 2016 Lower Deschutes River Water Quality Report

We are thrilled to announce the publication of the DRA’s 2016 Lower Deschutes River Water Quality Report. This report—along with three other reports we’ll be releasing over the next two months—is the culmination of the DRA’s most detailed investigation yet of the causes and extent of the ecological changes occurring in the lower Deschutes River.

An important aspect of the report analyzes hourly water quality data collected at River Mile 99, one mile below the Pelton Reregulating Dam, from February 18 through November 22, 2016. All data collected for pH, temperature, and dissolved oxygen are presented and analyzed, and compared against water quality requirements contained in the state-issued Clean Water Act § 401 Certification for the Pelton-Round Butte Complex, as well as Oregon’s water quality standards for the Deschutes Basin. Read the whole thing here.

This report represents the most complete public analysis yet of the impact of Selective Water Withdrawal operations on water quality below the Pelton-Round Butte Hydroelectric Complex. Key findings include:

  • Oregon’s water quality standard for pH in the Deschutes Basin (6.5-8.5 SU) was exceeded on 234 out of 279 days that data were collected (84%). 43% of the days sampled had pH measurements greater than 9.0.
  • Each year since 2011, Project operators have worked with the Oregon Department of Environmental Quality to purportedly weaken the water quality requirements in the Project’s Clean Water Act § 401 Certification. These changes include:
    • The defined spawning season for salmonids was changed from year-round to Oct. 15-June 15. This change allows the application of a lower dissolved oxygen standard during the non-spawning period (June 16-Oct. 14). However, this newly defined spawning period does not take into account the full season of resident trout spawning and egg incubation, as is required by the Oregon Administrative Rules. This has caused dissolved oxygen levels in the lower Deschutes River to fall below levels required to protect resident salmonids through egg incubation and fry emergence.
    • The water temperature that triggers the blending of cool bottom water from Lake Billy Chinook with warmer surface water has been markedly increased since the Selective Water Withdrawal tower began operations. This has allowed the release of 100% surface water into the lower Deschutes River to continue later into the summer.
  • Changes in pH and dissolved oxygen, documented by this study and ODEQ’s own data, clearly indicate that excess nutrients are being released into the lower Deschutes River from the surface waters of Lake Billy Chinook.

DRA’s 2016 Lower Deschutes River Water Quality Report clearly establishes that, in just seven years of operation, the Selective Water Withdrawal tower at Pelton-Round Butte has severely degraded water quality and threatens aquatic life below the Project. We believe this report will serve as an important document for all basin stakeholders in assessing the impact of tower operations on the river we all love.

A special thanks to all of our supporters, whose generosity and passion for the river has made all of our science work possible. We’d like to take this opportunity to specifically thank the various organizations and foundations who have provided funding to support this critical work, including:

  • The Oregon Wildlife Heritage Fund
  • Maybelle Clark MacDonald Fund
  • Flyfishers Club of Oregon/Flyfishers Foundation
  • Clark-Skamania Flyfishers
  • Mazamas
  • American Fly Fishing Trade Association
  • Tualatin Valley Chapter of Trout Unlimited
  • Washington County Fly Fishers

Cooler, cleaner H2O for the Deschutes!

Photo by Brian O’Keefe

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The Problem With the Water Quality Data in the PGE Lower Deschutes River Report by R2 Consultants

Pic 1 R2 Report

The above report (published in March of this year), as noted in prior DRA blog posts, was of a two-year study of the lower Deschutes River. The purpose of the report was to determine the magnitude of biological changes in the river due to the implementation of surface water withdrawal at Round Butte Dam. A baseline study was conducted in 1999-2001, which Portland General Electric (PGE) summarized in a report published in 2002.

Both studies were contracted and paid for by PGE and were a requirement of the Federal Energy Regulatory Commission license to operate the Pelton-Round Butte dams.

The water quality data from the most recent study can be found on pages 47 and 48 of the 2014-2015 report. The results document violations of the basin and statewide water quality standards in both years of the study. The most egregious violations were of the pH standard as established in Oregon Administrative Rules (OARs) 340-041-0021 and 340-041-0135. The Deschutes Basin Standard for pH is a maximum pH of 8.5. A pH of 7.0 is neutral (neither acid nor alkaline, greater than 7 is alkaline).

The authors attempt to diminish these violations by noting on page 46 of the report that, “Regarding the unusually high pH measurements taken in Spring 2015, since these are uniformly high, even in the reference sites, it is highly likely that the meter we used was off in its calibration. Therefore, any in situ measurements taken should be considered preliminary at best, and compared to official measurements taken by PGE or agencies.”

There are many problems with this statement.

R2 Resource Consultants are self-proclaimed experts in water quality monitoring and modeling, so one has to wonder how and why they would be unable to produce accurate water quality data? Why would they have calibration problems? If their equipment wasn’t functioning properly, why wouldn’t they use backup pH measuring equipment? If they didn’t have backup equipment, why couldn’t they borrow equipment or have it shipped in via overnight express? The pH measurement problems they most specifically refer to occurred over several days in April of 2015. That should have been enough time to correct any equipment problems.

There were also very high pH measurements in the three days of sampling in April/May of 2014 (10 out of 12 lower Deschutes River sites were above the 8.5 pH water quality standard). Were their instruments faulty then too?

Or is this an attempt to discard and disregard data that are indicative of water quality problems?

There is another potential reason that the high pH values were recorded during spring sampling in both years. When algae bloom, it increases pH. It does this by absorbing CO2 from water to conduct photosynthesis. The by-products of photosynthesis are sugar and oxygen. Notably, the dissolved oxygen levels on the dates of the high pH levels were also high, with dissolved oxygen saturation levels reaching up to 138%. This occurs when there is excessive algal growth.

We have noted extensive algae growth in the lower river this year, starting in February. We have also recorded pH levels of greater than 9 in April and May 2016.

Algae, early March 2016. One mile below Pelton-Round Butte Reregulating Dam.

Algae, early March 2016. One mile below Pelton-Round Butte Reregulating Dam.

Algae, late March 2016. One mile below Pelton-Round Butte Reregulating Dam.

Algae, late March 2016. One mile below Pelton-Round Butte Reregulating Dam.

We are troubled by the lack of explanation for R2’s “calibration problem(s).” It is standard procedure to have a quality control plan that includes details for meter calibration and procedures if they fail calibration. At the DRA, we maintain a log for each instrument we own. Recorded in each of these logs are the calibration dates, times and results. All instruments are calibrated before each day of water quality sampling. We carry backup equipment.

In the case of our in-river dwelling data instrument, once a month we perform “field audits” where we cross check the data it produces with independent meters and manual techniques. We cross check the performance of our meters.

We have such a stringent quality control program because two of our field staff worked for the Oregon Department of Environmental Quality (ODEQ) for decades, doing water quality work. We exercise the same quality control methodology that ODEQ uses. We would suggest that PGE require the same of contractors doing water quality work.

DRA water quality staff at work:

Larry Marxer measuring dissolved oxygen in river water, using the Winkler method.

Larry Marxer measuring dissolved oxygen in river water, using the Winkler method.

Rick Hafele doing water quality measurements on Lake Billy Chinook.

Rick Hafele doing water quality measurements on Lake Billy Chinook.

Greg McMillan going old school on water quality measurements in 1979 (when old school was just school, or maybe pre-school).

Greg McMillan going old school on water quality measurements in 1979 (when old school was just school, or maybe pre-school).

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The Troubling Loss of Antocha Crane Flies

By Greg McMillan and Rick Hafele

Antocha Crane Fly. Photo by Rick Hafele.

Antocha crane fly. Photo by Rick Hafele.

Antocha is just one genus of the family Tipulidae, a group well known as crane flies. As crane flies go Antocha is rather small, and while most crane fly larvae live in slow moving or stagnant water with silty or muddy substrate (some are also terrestrial), Antocha larvae prefer riffle areas of streams with clean cobble substrate. This little crane fly is found throughout North America, including most if not all of the streams in the Deschutes watershed. Until recently it was one of the insects of the lower Deschutes River that appeared every summer in moderate to large numbers. Whether trout found it of interest could be debated, but its presence was one of those reminders that summer had arrived on the lower Deschutes – but no longer.

Rick Hafele and Greg McMillan first noted the absence of Antocha crane flies in the lower Deschutes River in July of 2013. Until that time these dipterids had been abundant in the lower Deschutes River. By the summer of 2013 other species of aquatic insects had also been observed to be in decline, but Antocha just seemed to have disappeared.

We waited until 2014 to confirm our 2013 observations regarding the missing Antocha before saying anything publicly. We reported our observations here in our blog, and then through the observations of others in our 2014 Lower Deschutes River Macroinvertebrate Hatch Activity Survey Results. Our reports regarding the missing crane flies were initially met with little interest, if not skepticism, by resource management agencies and the Pelton-Round Butte Dam operators, but then confirmed by the R2 Resources Interim Report in the Portland General Electric Aquatic Macroinvertebrate and Periphyton Study. The final report from that study also notes that the disappearance of the crane flies in the lower Deschutes River occurred after the inception of selective water withdrawal at Round Butte Dam.

Antocha crane flies mating and laying eggs in the lower Deschutes River before surface water withdrawal began at Round Butte Dam. Photo by John Hazel.

Antocha crane flies mating and laying eggs in the lower Deschutes River before surface water withdrawal began at Round Butte Dam. Photo by John Hazel.

The final report from the PGE Lower Deschutes Aquatic Macroinvertebrate and Periphyton Study also mentions studies done on the Crooked River and Middle Deschutes (Vinson, 2005; and Vinson and Dinger, 2007; Reports prepared for U.S. Department of the Interior, Bureau of Land Management, National Aquatic Monitoring Center) that showed declines in Antocha populations in those rivers. It is worth noting that those studies were done in the years prior to implementation of surface water withdrawal from Lake Billy Chinook at Round Butte Dam in late 2009.

The PGE study concludes that:

“… Antocha crane flies were widely distributed in pre-SWW samples above and below the project but nearly absent post-SWW from nearly all sites including the Deschutes and Crooked Rivers upstream from the project. Significant numbers were observed post-SWW only in the Metolius River, a unique spring-dominated system with minimal development compared to the Crooked and Deschutes systems. Most likely, this change is a result of a broader environmental pattern as opposed to project-related effect. It is unknown whether this pattern represents normal annual variability or a longer term (sic) trend. However, this observation highlights the value of the upstream study sites in distinguishing project from non-project changes.” (Final Report, Lower Deschutes River Macroinvertebrate and Periphyton Study, R2 Resource Consultants, 2016, page 100.)

That conclusion seems to be hastily arrived at, and appears to us to be biased towards exonerating dam operations as a contributor to the disappearance of Antocha in the lower river. Yes, studies show that Antocha crane flies have nearly disappeared from the Crooked and Deschutes rivers above the project, and that decline happened prior to surface water withdrawal from Round Butte Dam. Even though the loss of Antocha is still evident a decade after it was first reported, the PGE report suggests that this could be due to “annual variability.”

The study’s authors go on to suggest that the only other alternative is that this is due to a “broader environmental pattern.” Yet they state that the Antocha population is intact in the Metolius River.

In another aquatic invertebrate study of Whychus Creek, Antocha was found to be present from 2005-2014 (Mazzacano, Effectiveness Monitoring in Whychus Creek; Benthic Macroinvertebrate Communities in 2005, 2009, and 2011-2014, The Xerces Society for Invertebrate Conservation, page 58).

Whychus Creek is a tributary to the Middle Deschutes River. The confluence of Whychus Creek and the Middle Deschutes River is about three miles above Lake Billy Chinook. A great deal of habitat restoration work has taken place in Whychus Creek in recent years thanks to the work of groups like the Deschutes Land Trust, the Upper Deschutes Watershed Council, Trout Unlimited, and others. The Portland General Electric Pelton Fund, along with other sources, has provided funding for this work.

So in at least two other streams the Antocha populations are intact. It would be interesting to look at other streams in the basin to see what the status of Antocha is. We believe it was very hasty and preemptive to draw the conclusion that this is due to a “broader environmental pattern” when only limited data is available from other streams.

Basin studies show that the Middle Deschutes and Crooked rivers have large anthropogenic influences due to population centers and agricultural runoff. That in turn results in higher levels of nutrients that lead to algae growth. As noted in our 2015 Lower Deschutes River Macroinvertebrate Hatch Activity Survey Results, Antocha crane flies lay eggs in the splash zone of river rocks. Stalked diatom algae, which have become common in the lower Deschutes River since implementation of surface water withdrawal from Lake Billy Chinook, form a barrier to the bare rock Antocha seem to favor for reproduction in the lower Deschutes River. This probably makes egg laying impossible.

Stalked diatom algae covering splash zone of rocks in lower Deschutes River. Photo by Greg McMillan.

Stalked diatom algae covering splash zone of rocks in lower Deschutes River. Photo by Greg McMillan.

From mid-November until late May the water discharged from the Pelton-Round Butte Hydroelectric Project consists of 100% surface water draw from Lake Billy Chinook. Even during summer and fall months, there is a minimum of 35% surface water draw (Pelton Round Butte Project, FERC No. 2030, Water Quality Report, 2015). We know that for much of the year, surface water in the forebay of Round Butte Dam consists primarily of water from the Crooked and Middle Deschutes rivers (Deschutes River Alliance 2015 Water Quality Report and unpublished data from 2016, pending publication in 2017).

Given that Antocha crane flies disappeared from the Crooked and Middle Deschutes rivers prior to the institution of surface water withdrawal, and surface water withdrawal is heavily influenced by the water quality of these rivers, we believe that there is another hypothesis for the massive decline of Antocha in the lower Deschutes River. We propose that the causative agent of Antocha decline in those rivers is now being passed down into the lower Deschutes River as a consequence of surface water withdrawal at Round Butte Dam.

That cause could be any, or a combination, of several possible agents.

The first is the nutrients in surface water withdrawal at Round Butte Dam fueling the stalked diatom proliferation in the lower river, which is denying access to clean rock surfaces necessary for Antocha mating and egg-laying.

The second possible cause is that a pesticide or other agent entering the Crooked and Middle Deschutes Rivers is being transferred downstream in surface water from Lake Billy Chinook.

Antocha crane flies have also been found to be susceptible to parasitic infestations (International Review of Hydrobiology, Vol. 92. Issue 4-5, pg. 545-553, August 2007). This raises a host of issues that could possibly be related to the ecological changes brought by surface water withdrawal from Lake Billy Chinook. A parasite could have been transported to the lower river via surface water withdrawal at Round Butte Dam, or water conditions changed by surface water withdrawal, could now be favoring a parasite that has possibly infected Antocha.

How important is the disappearance of Antocha crane flies? That is hard to tell. However their disappearance from the lower Deschutes River, and the Crooked and Middle Deschutes rivers, should be taken as an indication of an ecological change. Their disappearance warrants deeper investigation and not just casual dismissal of a phenomenon that could be indicative of a larger ecological problem.

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2015 Lower Deschutes River Aquatic Insect Hatch Activity Survey Results Report by Rick Hafele Now Available

The annual DRA aquatic insect hatch observation report for 2015 is posted to our website. Please click here to access the report.

Photo by Rick Hafele

Photo by Rick Hafele

This report, authored by Rick Hafele, is the result of the many hatch observations in 2015 by several professional guides on the lower Deschutes River. All observers received training at a Deschutes River Alliance workshop in Maupin in March of 2015. They then utilized a mobile device app to report their observations.

We want to give special thanks to the guides who participated (and continue to participate in 2016) in this process. They are: Brian Silvey, John Smeraglio, Evan Unti, Harley Faria, Alex Gonsiewski, and Dan Anthon. We would also like to thank Dave Moskowitz and Rick Trout for the reports they furnished.

The observations are summarized in this report. A continuing trend of earlier hatches, and of fewer and less dense hatches is noted once again in 2015. These trends were seen throughout the months of March to October. Declines from the previous two years were observed for all major groups of insects except midges, which remain unchanged.

Antocha crane fly adult. Photo by Rick Hafele.

Antocha crane fly adult. Photo by Rick Hafele.

The report is 29 pages long and full of information any angler needs to better understand fly-fishing the lower Deschutes River, as well as the trends in aquatic insect populations that have historically occupied the Deschutes River.

The DRA is especially grateful to Rick Hafele for his expertise in aquatic entomology and for the work he put into conceiving and organizing this ongoing monitoring effort, the collating and analysis of the observational data, and the writing of the report.

We intend to continue this monitoring effort to provide surveillance of the long-term trends in lower Deschutes River aquatic insects. The training for the 2016 hatch observers took place in March. We are already receiving their reports for the 2016 report. We’ve also added two benthic (river bottom) kick-sample sites that we began sampling in the fall of 2016.   Since Portland General Electric completed their macroinvertebrate and periphyton sampling in April/May of 2015, no one other than the DRA is monitoring aquatic insect populations in the lower Deschutes River.

Chuck Kenlan with an early evening fish that rose to a caddis imitation. Photo by Greg McMillan.

Chuck Kenlan with an early evening fish that rose to a caddis imitation. Photo by Greg McMillan.

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2014 Lower Deschutes River Aquatic Insect Hatch Report – by Greg McMillan

2014 Lower Deschutes River Aquatic Insect Hatch Survey Report

Now Available

Our 2014 Lower Deschutes River Aquatic Insect Hatch Survey by Rick Hafele is now available on our website. Rick, with the help of several guides and experienced fly anglers, compiled over 100 hatch observations in this report.

This is a worthwhile read to understand the hatches on the lower Deschutes. It’s also essential reading to understand the changes in aquatic insect populations and their hatch timing.

The single most startling result noted in the survey is the disappearance of the Antocha crane flies. The participants in this survey aren’t the only ones to note the disappearance of the Antochas. Portland General Electric and The Confederated Tribes of the Warm Springs Reservation, owners/operators of the Pelton-Round Butte Dam complex, hired a natural resources consultant to do a biological survey of the lower Deschutes River. That consultant, in their report, has also failed to find evidence of Antocha crane flies.

How important is the loss of a species of insect in the lower Deschutes? If it’s an indicator of river health, the answer is very important. And we believe the Antochas are an indicator of river health.   We believe that the cause of their demise is the algae that now grows in the splash zone on river rock in the lower Deschutes. It’s in the splash zone that adult crane flies lay their eggs.

Deschutes Crane Flies by John Hazel

Deschutes Crane Flies by John Hazel

This algae, new since the switch to surface water withdrawal at Round Butte Dam, is likely the result of a change in nutrients being discharged from the dam. DRA has reported on this in several previous posts.

Antochas did have value to anglers. During the time of their mating, they were sometimes swept off rocks and made available to feeding fish. The astute angler could be very successful if imitating them at these times. But they had a more important role, and that was as part of the larger food chain of the Deschutes River Canyon. That food chain includes (but is not limited to) fish, birds and bats. The loss of Antochas must not be taken lightly.

Photo by Dave Hughes

Antocha Crane Fly

Special thanks to Rick Hafele for his expertise and diligence in creating this important publication. Also, special thanks to the guides and anglers who made this report possible (John Smeraglio, Sam Sickles, Alex Gonsiewski, David Moskowitz, Steve Pribyl, Steve Light, Evan Unti, Rick Trout, and Damien Nurre).

Where Have All the Crane Flies Gone?

Antocha crane flies have been a staple of summertime on the lower Deschutes all of the years I’ve fished the lower river. And that’s a lot of years (measurable in decades). I’d say how many years, but it would make me feel old, very old. Not as old as some of my friends and fellow anglers, but old.

Photo by Dave Hughes

An Antocha crane fly occupying its place in nature.

These small flies (of the order Diptera, family Tipulidae) are most typically seen perched on rocks in river water, occupying the wet surface of the rock where air and water meet. They are frequently seen to be doing push-ups as they mate and lay eggs. They are made available to fish when wave action sometimes washes them off of the rocks they occupy. I often imitated these flies with a size 16 or 18 pink bodied compara-dun, which simultaneously imitated pale morning duns, which hatched concurrently with the annual appearance of crane flies on the lower Deschutes.

Three years ago these small dipterids began to disappear on the lower Deschutes. It was one of the events that turned out to be a harbinger of things to come. This past summer, only two individual crane fly sightings (of one crane fly each) were reported to the DRA’s Rick Hafele through guide and angler-generated hatch observations. I personally spent nearly sixty days on the river doing fieldwork this summer, and saw none. In the past, I saw them by the thousands, perhaps even hundreds of thousands. At their peak activity, they literally rimmed wet river rocks that had any exposed surface above the water line.

We believe that their disappearance is linked to the nuisance algae that have so pervasively spread in the lower river. This photo demonstrates why:

Photo by Greg McMillan

Algae-rimmed rocks on the Deschutes.  Photo by Greg McMillan

Note that the water line is covered with algae. In the first picture, the rock surface is clean. In the second, algae obscure the wet rock surfaces. We are currently hypothesizing that the algae prevent the crane flies from either being able to occupy these rocky surfaces, prevent egg laying , or alter egg survival. We do know that the timing of the appearance of these nuisance algae is in line with the loss of crane fly populations in the lower Deschutes.

How important is this loss of Antocha crane flies? No one knows. But rarely is the unintended loss of a benign species a good sign.   We know that other aquatic insects have declined in numbers. Our aquatic insect hatch database confirms this (last years report, from our initial pilot study, can be found here).

In another month or so we will have the results of our water quality-monitoring project ready for release. The data are currently undergoing statistical analysis, and once this is complete, report writing will begin. Algae growth and proliferation like we are seeing in the lower Deschutes the past three to four years is a consequence of a change in water quality, specifically nutrient loading.

Watch this website and blog for news on what we found.

Greg McMillan