PRB Fisheries Workshop

For over 20 years Portland General Electric and now the Confederated Tribes of Warm Springs have been hosting the Pelton Round Butte Fisheries Workshop.  This is an annual gathering of state and federal agencies, NGOs, and the curious to review and discuss the latest science on the Deschutes and its tributaries.  I have been going for a few years and find it fascinating.  This year should have the usual updates on reintroduction and fisheries health, the final results of the macroinvertebrate study, and the results of the water quality study.  It will be very interesting.

This year the workshop will be June 13 & 14 at Tetherow Resort in Bend.  Everyone is welcome and I encourage you to attend.  To get on the email list, contact Jessica Graeber (

At last year’s conference, I took over 7 pages of notes.  Below are the highlights from those notes.

Day 1 began with an interesting overview of the history of the Pelton Round Butte project including construction, fish passage attempts, and relicensing terms.  The dams were completed in 1964.  FERC relicensing began in 1986 and the final application was submitted in 1996.  Another 50 year license was granted in 2004.  The first fish were passed downstream in 2009, adult returns began in 2011.  The Confederated Tribes of Warm Springs become majority owners in 2030.  The primary issues the current FERC license is concerned with is surface currents to facilitate capture of downstream migrants and lower D water temps (warmer in the spring and cooler in the fall to mimic the temps that would exist if the dams were not in place).  In terms of water quality the primary goals are to meet standards for temps and dissolved oxygen and pH to the extent possible.  (It is next to impossible to meet goals for all 3 simultaneously.)

The 2016/17 year (which ended June 1) saw record numbers of juvenile spring chinook, steelhead, sockeye, and bull trout transported downstream.  Record numbers of kokanee were also captured, but they were put back into Lake Billy Chinook.  A major difference from the past was nighttime releases of 4,500 cfs through the Selective Water Withdrawal tower from March 15 through June 15.  PGE was not willing to state that this is the reason for the record out migrations as the end of the drought could have also played an important role.  While this is a welcome improvement, downstream migrant capture rates remain disappointing when compared to the hundreds of thousands of juveniles that are planted every year.  It remains unknown if the losses are in the rivers or in LBC.  There is evidence of steelhead remaining in Whychus as trout rather than out migrating.

Adult fish returns were a more mixed bag.  Only 43 steelhead returned, the lowest number so far.  (Of course, steelhead numbers also plummeted throughout the Pacific NW last year.)  As usual, most of those fish attempted to go up the Crooked River.  52 spring chinook returned as well as over 500 adult sockeye, both records.  Sockeye numbers were up from the previous record of around 100.  The chinook went up all the tributaries while the sockeye went up the Metolius.

Water quality measurements done by PGE and overseen by Oregon Department of Environmental Quality remain the same as in past years.  Temperatures and dissolved oxygen levels are in the desired range while pH levels remain slightly elevated during the summer.  I was sitting next to two ODEQ folks and asked them about this.  They stated that temps and DO are their primary concern, pH levels have always been elevated in the lower D, even before the operation of the SWW, and that there is no observable negative effect from it.  The ODEQ folks stated that they are waiting for results from the more in-depth water quality study currently underway and scheduled to be completed next year.

An update on the macroinvertebrate study was presented. This study was completed last year but ODEQ sent a letter asking for more analysis.  Much, although not all, of that analysis is now complete.  The bottom line is that the results of the study released in 2016 are likely not changing.  Overall, the aquatic insects in the lower D are healthier and more abundant now than pre-SWW, although their lifecycles have been pushed earlier and later in the year to coincide with the new temperature profile.  There is some remaining work to be done, but it is out of an abundance of caution and perhaps over analysis.  I asked the ODEQ folks and they said they have been working with the independent consultant on the re-analysis and are confident that the final report will be one they can support.

At the Day 1 social hour, I had a chance to talk to the ODFW fish biologist in Prineville about the sampling work that occurred on the Crooked last week.  Preliminary numbers are very encouraging.  He counted about 1,300 fish per mile with no evidence of gas bubble disease.  The fish were mostly smaller, up to 10″, so fishing could be quite good next year.  In April the fish count was significantly lower with evidence of gas bubbles appearing in many of the larger fish.

Day 2 was just a morning session this year.  First up was a discussion of smolt survival after being released from below PRB and tracked to the mouth.  Sockeye, spring chinook, and steelhead were all tracked, half released during the day and half at night.  There were significant differences between individual fish and results from day and night releases, but overall most fish made it to the mouth within 2 days.  The longest took 19 days.  The most striking result was the dramatically improved survival rate with fish that were released at night, with a 27% improvement for steelhead and 36% improvement for chinook.

ODFW gave their annual fisheries health report for the lower Deschutes.  Since the 1970s they have been electrofishing the same 4 stretches from Warm Springs to Jones Creek.  As reported the past 3 years, the trout fishery is in “excellent” health.  Condition factors were good before operation of the SWW and they have slightly improved since then.  The fish are bigger and healthier.  They appear to be growing faster, not just living longer, which would make sense given the improved macro population to feed on.  Last year they also did a creel survey from April to June from Trout Creek to below Maupin.  The overall catch rate is 0.78 fish per hour which is also excellent and an improvement from pre-SWW.  0.78 fish per hour is the highest catch rate for any water in the entire Deschutes Basin and Cascade Lakes with the exception of the Crooked which is over 1.  0.78 is also better than rivers in Montana.  Finally, following reports of increased bass near the mouth last summer they did some electrofishing and found 50 bass.   This was repeated in September and 1 bass was found.   There was no evidence of spawners.  In May of this year they found 2 bass.  ODFW has records going back to the 1970s of periodically finding bass in the lower D and they do not seem overly concerned now although they plan to keep electrofishing.

Most of the above is primarily updates of previously reported and ongoing studies.  The very last presentation was something entirely new, interesting, and potentially important. The water released from PRB is a mix of top and bottom water blended to meet a temperature profile calculated to mimic what it would be if the dams were not in place.  That calculation takes into account the temperature of the 3 main tributaries (Crooked, Deschutes, and Metolius) when they enter LBC as well as the air temp at the Bend-Redmond Airport.  They have been doing this but noticed that the actual temps have been higher than predicted, causing them to release of more bottom water than anticipated to provide additional cooling.

An independent hydrology/geology consultant was hired to look into it.  It was a fascinating and detailed presentation, but the bottom line is that LBC is being fed by a significant amount of underground warm/hot springs.  While we all think of the springs around here being cold, once you get close to LBC the geology changes and the springs are warm, some even hot.  They are feeding into LBC below surface level.  The estimate is that this warm groundwater is adding 30% to the overall temperature of the lake.

I asked the obvious question: if the withdrawal model takes air temp and trib surface water temp into consideration, shouldn’t it also input this large flow of warm water to mimic what would be the “natural” temperature profile.  If so, then shouldn’t the lower D be managed to be even warmer than it currently is?  (Not that anyone wants that.)  PGE dodged the question and stated that they are now waiting for the results of the in-depth water quality study due in 2018.  They will combine the results of that study with this warm groundwater study and propose release modifications as required.  That should be interesting.

Final note: the hydrologist estimates that it takes 3,500 to 4,700 years for water to travel from North Sister through the aquifer to LBC.  Drink up!