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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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.

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DRA Releases Reports

On March 4, we posted two new reports under the “Reports” tab on our website.

The first report is the analysis of our 2014 thermal imaging survey of the lower Deschutes River.

Slide1

This report is the analysis of the first known thermal imaging look at mid-summer temperature behavior in the lower river.  There were many unanticipated surprises from the imaging, but two findings are of greatest importance.

  • The thermal behavior of water discharged from the Pelton-Round Butte Complex during nighttime hours is unaffected by “canyon effect.” Canyon effect warms the water during the day as a product of solar radiation exposure.  Nighttime discharge, however, avoids much of the daytime warming effect.   Yet all temperature calculations used for temperature management by dam operations act as if water temperature and temperature behavior are the same day and night.  It has also been stated by the dam operators that “cooler temperature discharge from the dams wouldn’t make any difference” because of “canyon effect.”  Our findings contradict that.
  • Solar radiation (down-bound long wave radiation) is far more important than air temperature in determining river temperatures. Solar radiation warms both air and the water in the river.  That means that shade from canyon walls and riparian vegetation is important in maintaining cooler water in the river.  Air temperature in Redmond is also an important factor in determining the goal for temperature management for dam discharge, yet air temperature has little effect on water temperature.

The second report describes our data and findings from the 2015 water quality study we did in Lake Billy Chinook and in the lower river just below the Pelton-Round Butte Dam Complex. 

Slide2

The Selective Water Withdrawal Tower at Round Butte Dam (the uppermost dam of the three dam complex at Pelton-Round Butte) has intake portals in the top 30 feet of the reservoir, and at 265 feet of depth.  To better understand the water quality effects of Tower operations and selective water withdrawal, we sampled surface water and water at depth in front of the Tower, as well as in the river below the dams.

The data we gathered demonstrated many things, and also raised more questions that we will be attempting to answer through the water quality sampling we started in February of this year. Our results from 2015 shed light on a number of critical factors, including that:

  • Surface water withdrawn from Lake Billy Chinook, for much of the year, consists primarily of water from the Crooked River Arm of the reservoir.
  • Water from the Crooked River Arm is warmer, and of poor water quality (the Crooked River water quality above the reservoir is rated as “poor” by Oregon Department of Environmental Quality). Plus, the water in the Crooked River Arm supports the densest level of algae growth in the reservoir.  In contrast, water from the Metolius River, which, because of its colder temperature constitutes most of the water at the depth of 265’, is of high quality (based on ODEQ data, as well as our own data).

Questions we are hoping to answer in 2016 include (but are not limited to):

  • What is the “nutrient load” entering Lake Billy Chinook from the three tributaries, and when does it get discharged from the dam complex into the lower Deschutes River? Algae in the upper water of the reservoir actually help decrease nutrient levels during summertime growth, but nutrients in surface water discharged in late fall, early winter and spring are not likely attenuated by that algae, and probably contributes significantly to the growth of nuisance algae that has been documented in the lower river.  So we are now tracking nutrient levels at the surface and at depth in the reservoir and below the dams.
  • Is the surface water in the Crooked River Arm of Lake Billy Chinook too toxic for migratory juvenile fish survival during major algae blooms due to high pH, high temperature and/or other variables?
  • Is operation of the dam complex in compliance with the water quality requirements of the Pelton-Round Butte Section 401 Certification under the Clean Water Act and the Federal Energy Regulatory Commission license?

We would also like to announce that we are (finally!) getting some of our raw water quality data posted on our website.  We are open-sourcing the data for all to view or use.  It will take some time to get everything posted, but we will be working on this going forward.

We hope to post updates on our work throughout the year.  So please stay tuned.

Deep and heartfelt thanks to our donors and supporters for making this work possible!

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Happy Holidays From The Staff and Board of Directors Of the Deschutes River Alliance!

We would like to wish everyone the happiest of holidays and all the best in the New Year!

Here at the DRA, Christmas came early this year.  Thanks to a special $20,000 donation from one of our supporters, we have been able to purchase water quality data equipment to create a semi-permanent water quality-monitoring site on the lower Deschutes River.

Photo by Brian O'Keefe.

Photo by Brian O’Keefe.

The water quality equipment we are acquiring with this special gift will give us the ability to monitor temperature, pH, dissolved oxygen, turbidity and chlorophyll-a on an ongoing 24-7 basis.  We have already been doing aquatic insect sampling at the site where the equipment will be deployed, and will continue to do so throughout the 2016 year and beyond.  The site also has a high density of spawning gravel, and we’ll be able to document spawning periods and activity.

We are incredibly grateful for this gift and wish to thank the private donor who made this possible.

Photo by Greg McMillan.

Photo by Greg McMillan.

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Deschutes River Alliance Reveals 2016 Science Plan

Our 2016 Science Plan is now posted to our website, under the Reports tab.

Our annual science plans have evolved over the course of the past two years.  The first year was directed at determining if the changes (alterations in aquatic insect populations and nuisance algae proliferation) we had been observing in the lower Deschutes River began directly below the Pelton-Round Butte Dam Complex and continued to the mouth, or if there was a source downstream from the dams causing these changes.  These efforts confirmed that alterations in aquatic insect populations and the nuisance algal blooms begin immediately below the dams.

Algae at Disney Riffle, 1 mile below the Pelton-Round Butte Dam Complex. Photo by Greg McMillan.

Algae at Disney Riffle, 1 mile below the Pelton-Round Butte Dam Complex. Photo by Greg McMillan.

As a consequence, in 2015 we realized we needed to understand the quality of water released from the Selected Water Withdrawal Tower in the Lake Billy Chinook reservoir, which largely controls the water quality in the lower river.  To determine that, we began to conduct water quality sampling in Lake Billy Chinook.  We’ve been sampling both surface water and water at depth since the beginning of June 2015.

We’ve learned a few fundamental facts about Lake Billy Chinook:

  • The water at the bottom of Round Butte Dam forebay is roughly twenty degrees (Fahrenheit) cooler at depth than at the surface during the summer.
  • The pH at the surface in the forebay and Crooked River Arms approaches 10 (highest recorded pH was 9.9). We did a search of the scientific literature and determined that the maximal pH salmonids can tolerate for any prolonged period of time is 8.5.  The water at depth has a much more tolerable pH of 7 to 8.
  • We also learned the primary nutrient source (for both nitrogen- and phosphorous-based nutrients) in Lake Billy Chinook, is the Crooked River. The Middle Deschutes also makes a contribution to that nutrient load.  The Metolius is relatively low in nutrients, especially nitrogen-based nutrients.  These nutrients are what fuel algal blooms.

We have hypothesized that the massive algal blooms in Lake Billy Chinook have acted as a filter for nutrients.  The nutrients are consumed by the algae when they grow rapidly with exposure to warm temperatures and sunlight. The algae then die in late summer and fall.  As the reservoir cools in the fall, the previously warmer water at the surface cools and mixes with water at the bottom.  We believe that in the past this allowed the reservoir to sequester nutrients and prevent them from being discharged into the lower river at the rate they are today.

Our results this summer do indeed show a reduction in surface water nutrient levels as algae activity increases.  In the winter and spring, prior to the reservoir algae blooms, 100% surface water is being discharged into the lower river.  We believe that this is when the lower river likely becomes loaded with the nutrients that trigger the widespread nuisance algal growth we’ve all observed and slipped on!

This year we will begin sampling reservoir water at the surface and at depth in February.  This will allow us to determine if the nutrient cycling described above is indeed taking place.

We will also be continuing our aquatic insect sampling work at two locations below the dam complex, along with our aquatic insect hatch survey.

Lastly, we’ve been fortunate to be given funding for a high quality continuous water quality sampling and recording device that will be installed below the dam complex.  This will allow us to understand the hourly, daily, and seasonal changes in water quality discharged from the dam complex.

We wish to thank all of our supporters for making this work possible.  Without your continued contributions we would be unable to pursue answers to these critically important research questions.  Funding for our 2016 Science Plan is not yet complete.  We are grateful for any contributions you can provide to help us achieve these research goals.  Effective advocacy is founded on strong scientific research. Thank you!

Donate here.

Water quality monitoring on Lake Billy Chinook, 2015. Photo by Greg McMillan.

Water quality monitoring on Lake Billy Chinook, 2015. Photo by Greg McMillan.

Water quality monitoring equipment, Lake Billy Chinook, 2015. Photo by Greg McMillan.

Water quality monitoring equipment, Lake Billy Chinook, 2015. Photo by Greg McMillan.

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A Second Type of Algae Plagues the Lower Deschutes

By Greg McMillan and the Board of Directors of the Deschutes River Alliance, to especially include Cam Groner and Rick Hafele

In the words of DRA board member John Hazel, “It’s been a rugged summer.”  He’s right.  Drought, fire, smoke, warm water temperatures, fish die-offs, and fishing closures have all plagued the lower Deschutes River this year.  Now we have a new problem.  As if the lower Deschutes hasn’t had enough problems already.

Starting two weeks ago we started receiving emails and phone calls about a free-floating, green filamentous algae being present in the river.  It was draping itself in clumps over flies, knots in fishing lines, lures, side-planers and anchor lines on boats.  Shortly after that we started hearing from individuals with pumps in the river for domestic and irrigation withdrawals.  The algae was clogging the screens on their pumps.  Next we heard that the water pump at the fish counting station at Sherars Falls was suffering from the same problem with clogged screens.   The impact to irrigation pumps has resulted in screens having to be cleaned several times a day.  This puts very expensive pumps at risk of serious damage.

The potential economic consequences of this are hard to estimate, but it does have an impact.  Anglers are already avoiding the lower Deschutes due to warm water, a slippery river bottom, lack of aquatic insect hatches and turbidity from White River.  This impacts guides, outfitters and other businesses dependent upon the angling economy.

For those with pumps in the river, the cost of a damaged pump, labor to clean screens, or an outright inability to irrigate would be damaging to their incomes.  These incomes pay the tax dollars that support Wasco County and the Maupin School District.

The Algae

These stringy looking dark green algae have been presumptively identified as Cladophora, with possibly some Anabaena mixed in.  Cladophora has been observed in the lower Deschutes River for a long time.  But never in quantities like are being observed now.

The peak time for growth of Cladophora is typically late spring and early summer, although it can undergo a growth spurt in fall as decomposing organic matter provides nutrients to stimulate its biological activity.

Cladophora is widespread globally.  Cladophora blooms in the Great Lakes are legendarily bad and have created major environmental problems including fish die-offs.  This happens when the Cladophora dies and starts to decay, using up oxygen in the water and creating low oxygen conditions for fish and other aquatic organisms.  We are not likely to see fish die-offs due to Cladophora in the lower Deschutes as long as the flowing water in the river helps keep oxygen at adequate levels.

The growth of Cladophora has probably reached its peak in the lower Deschutes River, as well as its maximum life expectancy.  It is now detaching from the substrate in the river and floating off in the current for the last of its short life.

Cladophora sample collected from the lower Deschutes River on August, 16, 2015. Photo by Greg McMillan.

Cladophora sample collected from the lower Deschutes River on August, 16, 2015. Photo by Greg McMillan.

Why So Much Cladophora Now?

Cladophora blooms like we are seeing in the lower Deschutes River are invariably the consequence of an increased nutrient load in the river.  The nutrients are nitrogen and phosphorous.  Warm water helps fuel the growth of Cladophora.

This summer has been very warm, even downright hot at times.  Temperature management at the Pelton-Round Butte Dam Complex has used large amounts of surface water to increase dam discharge water temperatures in accordance with the Without Project Temperature (WPT, and previously called Natural Thermal Potential) model utilized by the dam owner/operators (Portland General Electric and The Confederated Tribes of the Warm Springs Reservation). In a recent blog post we described how this model works and how it results in the harmful warming of the lower river during times of warmer air temperatures.

During our fieldwork in Lake Billy Chinook this year, we’ve been seeking to determine how dam operations have altered the nutrient load in the lower Deschutes.  We’ve found that of the three tributaries, the Crooked River has the highest nutrient load, while the Metolius River has the lowest.  The Metolius, in our sampling, has had no detectable nitrogen based nutrients.

The Metolius River enters the reservoir and then flows into the forebay of the dam at depths approaching 350 feet.  The Crooked River enters the forebay at about 120 feet of depth (the Middle Deschutes enters the Crooked River Arm about ½ mile south of the forebay).  The result is that the combined Crooked and Middle Deschutes River water sits on top of the Metolius River water during warm months.  Once the lake cools in mid- to late fall, the lake begins to “turn over” or mix.

The consequence of this is that the surface water in the forebay consists primarily of Crooked River water.  To see how the nutrient load in the Crooked River water fuels algae growth, take a look at the surface water in the Crooked River Arm of the reservoir in this unaltered photo:

Photo by Greg McMillan.

Photo by Greg McMillan.

Here is what the surface water looks like in the forebay of Round Butte Dam during summer:

Photo by Greg McMillan.

Photo by Greg McMillan.

By mid-summer the algae in the reservoir have used much of the nutrients for their own growth, but through spring and early summer that nutrient laden water is discharged into the lower river.   The result is more rapid algal growth.  And not just with Cladophora, but also with the stalked diatoms we’ve been documenting in the lower river that have contributed to the decline of aquatic insects.

Prior to the completion of the Surface Water Withdrawal Tower at Round Butte Dam in 2009, Metolius River water made up the bulk of the water drawn from the reservoir for power production.  We didn’t have these problems in the lower river prior to operation of the SWW Tower.

We are certain that these consequences of surface water withdrawal were not intended in the design and implementation of the Selective Water Withdrawal program that attempted to provide currents in the reservoir for juvenile fish migration.

The Solution

It has been demonstrated in cases of other Cladophora blooms that controlling nutrient load reduces or eliminates the problem.  That can be done in this case.  And should be done by reducing the amount of warm, nutrient-laden surface water being discharged into the lower Deschutes.  Nuisance algae problems have been increasing annually since the initiation of surface water withdrawal at Round Butte Dam.

We need to develop the political will to push PGE to alter dam operations in a fashion that eliminates the nutrient loading of the lower Deschutes River.  This is possible now with the adaptive management language in the dam operating license.

We also need the Oregon Department of Environmental Quality to stop ignoring the ongoing violations of water quality standards in the lower Deschutes River.  This will require in-depth water quality studies that could take years to get done.  So it needs to start now.  This is the long-term remedy to the algae problems in the lower Deschutes River.

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The Low Down on High Temperatures in the Lower Deschutes River

by Greg McMillan & the Board of Directors of the Deschutes River Alliance

Lower Deschutes River. Photo by Robert Sheley.

Lower Deschutes River. Photo by Robert Sheley.

Introduction

It’s been a rough summer.  No one anticipated the fish die offs and warm water temperatures to the degree we experienced in June and July.

Fortunately, we dodged the bullet with a second heat wave.  It was of short duration, and then broken by cooler temperatures, cloud cover and some rain.

But it was long enough to see a trend emerge regarding temperature management at the Pelton-Round Butte Dam Complex.  The dam operators were already warming up discharge temperatures, and warming the lower river, until we got a break from the heat.  They were once again artificially raising the temperature of the lower river in the face of already naturally warming temperatures.  Here’s what it looked like (these temperatures are from the Pelton Reregulation Dam tailrace):

Water temperatures at Madras gage, July 27 - August 3, 2015. Source: USGS online.

Water temperatures at Madras gage, July 27 – August 3, 2015. Source: USGS online.

During the same time frame, here is what was happening down at the mouth of the Deschutes River:

Water temperatures at Moody gage, July 27 - August 3, 2015. Source: USGS online.

Water temperatures at Moody gage, July 27 – August 3, 2015. Source: USGS online.

Observations

There are several observations to be made here:

  • As the weather warmed, so did the temperature at the Pelton Reregulation Dam tailrace. This is in accordance with Portland General Electric/Confederated Tribes of the Warm Springs Reservation “Without Project Temperature” calculation that is based on a mathematical model.  The WPT calculation estimates (or models) what the water temperature would be if the dams were not present.  WPT is then achieved by  mixing bottom and surface water at the Selective Water Withdrawal Tower at Round Butte Dam, before it is passed downstream to Pelton Dam and the Reregulation Dam.  Here is the equation:

Water Temperature Pelton = 2.8+(0.79)(Water Temperature into LBC)+(0.071)(7-day Ave Air Temperature Redmond Airport)

  • This PGE model uses the water temperatures of the tributaries (Metolius, Middle Deschutes and Crooked Rivers) entering Lake Billy Chinook, along with air temperature at Redmond airport, to derive the calculated target temperature (WPT) for dam discharge.
  • The lower river, running for 100 miles below the dams, has a daily swing of nearly six degrees during the summer. The tributaries above Lake Billy Chinook have a similar swing in daily temperatures, varying by up to six degrees between morning and late afternoon temperatures.
  • The discharge temperature at the dam complex only varies about 1 to 1 ½ degrees daily.
  • The temperature discharged from the Reregulation Dam tailrace has a major influence on lower Deschutes River water temperatures.
  • The temperature management model warms the lower Deschutes River in spring and summer, but cools it in the fall. Based on annual temperature curves, the spring/summer warming is much greater than the cooling in the fall.  Therefore, the lower Deschutes is experiencing net warming during a year-long cycle.
  • The temperature model for the dams increases temperature in the lower Deschutes when the lower river is already warm (at times too warm) in spring and summer.

It should be noted that the stated goal of temperature management using the Selective Water Withdrawal Tower is to “eliminate the thermal presence” of the Pelton-Round Butte Complex.

These observations made us curious.  How can you manage water temperature with the goal that the dams would be thermally invisible, and yet not have the daily variances that mimic a natural river?

In trying to figure this out, we also wondered what tributary water temperature is being used to calculate the Without Project Temperature goal?  Is it the average or mean daily temperature?  Is it the minimum daily temperature?  This would be the most beneficial temperature for the biology of the river during heat waves.  Or is it the maximum, warmest temperature of the day?

The Answers

We turned to the Portland General Electric/Confederated Tribes of Warm Springs Reservation annual water quality report that was recently submitted to the Federal Energy Regulatory Commission for the 2014-operating year to try to answer these questions.

It turns out that the tributary temperature used to calculate the Without Project Temperature, and corresponding blend at the Selective Water Withdrawal Tower target for dam discharge, is based on a 7-day average of the peak (warmest or maximum) temperature of each day in the 7-day calculation.  This means that the overnight cooling, and cooler temperatures that prevail throughout most of the day, are ignored.  These cooler temperatures are the temperatures that fish and other organisms rely on to recover from the brief daily period of peak temperatures during summer heat waves, and especially in desert rivers.  It should also be noted that the maximum temperature is only of short duration daily.  But the model acts as if it is the only temperature of the day.

Metolius River water temperatures, Grandview gage, July 19 - July 25, 2015. Source: USGS online.

Metolius River water temperatures, Grandview gage, July 19 – July 25, 2015. Source: USGS online.

The red line in the graph above indicates the temperatures from the tributaries above Lake Billy Chinook used in calculating Without Project Temperature (WPT).

In other words, the dam operators are warming the river during spring and summer well beyond what would be its normal state without the dams because they are artificially managing discharge temperature based on the maximum temperature of the above reservoir tributaries, not the minimum or average daily temperature of the tributaries.

Biological Effects

Charles Huntington, working under contract to PGE, did the seminal work that was done on understanding water temperature behavior in the lower Deschutes.  The work was completed and published in April of 1999.  It became the foundation of how water temperature at the dams would be managed.

In the published results of that study, the impact of temperature changes to the biology of the lower river was only minimally examined.  The most discussion was in regard to changes in the timing of emergence of salmonid alevins from spawning gravel.  The report concludes that juvenile emergence would happen sooner in warmer water conditions.  No impact to the success rate of emergence is noted, or suggested, as a benefit of warmer temperatures.

The question regarding what the impacts and effects on other biota (life forms) is asked, but never answered in the report.  Impacts to resident fish species, aquatic insects, aquatic plant life and algae are not examined.

No mention is made in the report of the role the lower Deschutes plays as a thermal refuge for upstream migrating adult salmonids in the Columbia River when it reaches maximum daytime temperatures during the summer.

No mention is made of what would happen if increasing temperatures, as a result of dam operations, in the lower river during spring and summer, reached the point of causing heat stress in fish.  No defined threshold was set as a maximum river temperature that should be reached before overriding the “mathematical model” to interject human judgment and decision-making.

What is discussed is the role dam discharge temperature plays in affecting temperatures downstream from the dams.  In varying conditions, dam discharge temperature can affect lower river water temperatures as far down as the mouth.  Yet the dam operators are only held responsible for the dam discharge temperature at the Reregulation Dam, not the impacts downstream.

What We Think Should Be Done

It’s time for a reexamination of how water temperature is managed in the lower Deschutes River.   This reexamination should be a more holistic approach to the health of the river and its resident species.

Thresholds should be set where protection of aquatic species is the primary goal for temperature management.

The 2005 dam operating license allows for, and even mandates, adaptive management, meaning changes can be made when new information shows that current methods are flawed. This means PGE, the Tribes, and the agencies responsible for protecting the aquatic health of the river can act now to lower the temperature of water released from the dams.

Dead spring Chinook salmon, July 10, 2015. Cause of death determined to be infection due to heat-related stress. Photo by Andrew Dutterer.

A victim of warm water temperatures. Dead spring Chinook salmon found in lower Deschutes River below Nena boat launch, July 10, 2015.  Photo by Andrew Dutterer.

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

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