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.

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

Click here to Donate.

Click here to sign up for the Deschutes River Alliance email newsletter.

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:

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

Click here to Donate.

Click here to sign up for the Deschutes River Alliance email newsletter.

2016 Stonefly Hatch: A Recap

Photo by Rick Hafele.

Photo by Rick Hafele.

It’s come and gone. No one is even talking about it any longer. Why? Well, it wasn’t exactly epic. Or was it?

Here’s the lowdown on the 2016 stonefly hatch based on personal observation; reports from friends, guides and outfitters; emails; and reports to our hatch observer database. This collectively represents hundreds of fishing days, if not over a thousand. None of this will be a surprise to those who were there for it. And many were there! The annual stonefly hatch remains the single largest trout fishing frenzy on the lower Deschutes River.

The first salmonflies were seen mid-April once again this year. Golden stones were seen not long after. Both were first spotted down below Sherars Falls. The big bugs appeared very sporadically until early May. Then numbers began to pick up and the hatch spread further upstream to well above the locked gate at the upper end of the access road above Maupin.   There were a few scattered reports of good numbers of stoneflies during that time. If you were fortunate enough to be on the river those days, the fishing was off the hook.

Then harsh weather set in. It got colder and there were heavy rains and the hatch all but disappeared but for a few hardy bugs clinging to grass and alder leaves.

Days later, the bad weather turned back to good weather and the hatch started back up, progressing up to the Kaskela area. Once more, if you were on top of the hatch in the right location, fishing was excellent. Then once again the weather turned wet and cold for days on end. The bugs again became hard to find. The quality of the fishing suffered. The last guide report of large numbers of salmonflies or golden stones seen on the river was May 17th. Only low to moderate numbers were seen after that until the final observed golden stones were reported on June 5th.

Photo by Brian O'Keefe

Photo by Brian O’Keefe

When weather conditions in the canyon were wet and cold, it was hard to find a stonefly anywhere. The trees and grass were bare. The big bugs were hiding from the conditions. If they aren’t out crawling all over the place, they aren’t finding mates. If they aren’t finding mates, no mating takes place.

This pattern repeated itself three times. Finally a meager representation of the hatches of earlier years hung on for about a week and half, reaching all the way up to Dizney Riffle. Then it fizzled out all together.

Mixed in with the stoneflies in mid-May was about a week and half period where everything was hatching. Green drakes, pale morning duns, pale evening duns, Beatis, caddis, it was all happening at once. There were even a few Antocha crane flies seen! But all of that ended as quickly as it began. And the total numbers weren’t all that exciting. It was perplexing to see June and July hatches in mid-May.

We are still getting some reports of good numbers of caddis in the tops of alders at last light on calm evenings. But the mayfly hatches of early to mid-summer are now totally missing in action.

What meaning does all of this have for the lower Deschutes River and the future of aquatic insect species? If this year had been a one time, one-off affair, it would probably mean little, being what biologists call annual variability. But it’s become a common way for spring to unfold on the lower river.

Most disconcerting is the role this might be playing in stonefly reproduction. Salmonflies emerge after three to four years as nymphs, golden stones after two to three years as nymphs.   Any impact of this year’s weather on mating won’t be seen until 2018 to 2020. The problem is this: with warmer winter and early spring river temperatures as a consequence of surface water withdrawal at Round Butte Dam, stoneflies emerge sooner and into the often harsh conditions of early spring, not late spring/early summer as they used to. The consequence is that reliably they are now challenged to find mates and get their reproduction needs accomplished.

Anyone who has spent years on the lower Deschutes River knows that stonefly numbers are down. Way down. According to Portland General Electric’s Lower Deschutes River Macroinvertebrate and Periphyton Study (page 97), “Stoneflies were not numerically abundant, but were widely distributed and contributed substantially to the invertebrate biomass by virtue of the often large size.”  That was some nice positive spin in the end of that quote, but the reality is that stoneflies are no longer “numerically abundant.” Unlike with many of the mayfly species and Antocha crane flies, this is probably not linked to the nuisance algae growth in the lower river.

Salmonflies as nymphs are detritivores, meaning they scavenge broadly across a river bottom eating dead material, mostly from plants. Golden stoneflies are roving predators and tend to feed on slow moving macroinvertebrates like midge larvae and worms. So the documented increase in worm populations in the lower river should be benefiting them. Nuisance algae are less likely to affect stoneflies as they spend time crawling between or under rocks, avoiding the algae covered top and side surfaces.

That means the declining numbers are most likely due to something else. Most likely that “something else” is hatching early into weather conditions not conducive to mating activity for much of the short adult phase of their relatively long lives. If reproductive success declines, the population declines.

June was a much warmer, drier month than May this year (like most years) on the lower Deschutes River. We’re guessing the stoneflies would have preferred those conditions.

Photo by Brian O'Keefe.

Photo by Brian O’Keefe.

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

Click here to Donate.

Click here to sign up for the Deschutes River Alliance email newsletter.

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.

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

Click here to Donate.

Click here to sign up for the Deschutes River Alliance email newsletter.

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