New pGE Study confirms water quality decline

 

For the past six years the DRA has been monitoring and reporting on the water quality problems in the lower Deschutes River that started when the Selective Water Withdrawal Tower began operation in late 2009. In May of this year we released our 2018 annual water quality report where results from 2018 again showed numerous exceedances of Oregon’s water quality standards in the lower Deschutes River. Conclusions from that report are troubling and clear. They include:

• Tower operations have not created a natural thermal regime nor resolved temperature exceedances. In fact, water temperatures in the lower Deschutes River exceeded the standard for spawning salmon and steelhead from May 17th to June 15th and the temperature standard for spawning trout from May 17th until mid-September.

• Dissolved oxygen failed to meet the minimum threshold for salmon/steelhead and trout spawning use from June 7, 2018 through August 14, 2018.

• And most serious, pH measurements exceeded the upper limit for the Deschutes basin pH standard (8.5 standard units) every
day
from the start of data collection on March 20, 2018 until November 29, 2018.

DRA has consistently connected the change to surface water release from Lake Billy Chinook (LBC) to the observed water quality degradation in the lower Deschutes River. Now, with the June 20, 2019 release of their own three-year water quality study, the project operators have contributed substantial data and analysis that strongly supports that connection.

The 620-page report, paid for by PGE and titled Water Quality Study for the Pelton Round Butte Project and the Lower Deschutes River: Monitoring & Modeling, was completed by Joe Eilers and Kellie Vache of MaxDepth Aquatics, Inc. The report, which we affectionately call “the Eilers’ Report,” is the result of three years of intensive water quality data collection (2015-2017) and almost three years of data analysis. While it is impossible to adequately summarize here a 620-page report in a few hundred words, the report makes it clear that water quality in the lower Deschutes River has declined since tower operations began, and the reason for the decline is the release of surface water from Lake Billy Chinook. The following quotes from the report confirm the observations and concerns of DRA and river users since the tower commenced operations.

On page 309: The LDR [lower Deschutes River] is warmer in the spring as a result of warmer discharge being released from LBC. Increased river temperatures promote a higher rate of metabolism for organisms and encourage increased periphyton growth. 

On page 310:  pH values appear to have increased slightly in the LDR based on comparing ODEQ AWQMP [ambient water quality monitoring program] data to continuous 72-hr data collected in 1997.  

On page 310: A comparison of the water quality data collected in this study and data collected prior to the installation of the SWW shows that concentrations of nutrients released from the Project have also changed since the SWW was installed. 

Also on page 310: The data show a large increase in NO3 [nitrate] at that site [hwy bridge 26, RM 97.6] and a slightly smaller increase at the Deschutes River SRA [state recreation area] site at the mouth (RM 0.1). In comparison with the 1997 data, NO3 showed a twofold increase in May 2016 and July 2015 and 2016 at the ReReg Dam, and those increases remained throughout the length of the river in May and July 2016.

On page 548: Although phosphorus is highly available throughout the LDR, nitrogen uptake is substantial, indicating that nitrogen is the limiting nutrient. Therefore, a reduction in NO3 is needed to reduce the periphyton biomass in the LDR.

Not only does the Eilers’ Report corroborate DRA’s findings, but it also provides a possible path forward to correct the problems created by surface water releases from LBC.  The question we must ask now is whether all concerned can find consensus based on recently published science and act to restore the health of the lower Deschutes River.