Water Quality and Aquatic Insects: A Story of Change in the lower Deschutes River

Do you ever think about the diversity and abundance of life that lives within the rocks and banks of a river? Aquatic entomologists study the organisms that inhabit the substrate, or benthic zone, in lakes and streams. The lower Deschutes River is historically well known for its abundant and diverse insect population that provide food for trout, birds, and other animals. Recent changes in the benthic zone’s appearance, including prolific algae growth, prompted concern for the aquatic insects that require clean and suitable substrate to thrive.

October caddisfly (Dicosmoecus sp.) lava. Photo by Rick Hafele.

 

In 2015 and 2016 the Deschutes River Alliance Science Team, with guidance from our trained aquatic entomologist Rick Hafele, collected benthic samples for analysis. We used methods developed by the Oregon Department of Environmental Quality and U.S. Environmental Protection Agency to collect and assess the macroinvertebrates at two sites in the lower Deschutes River. The 2015/2016 Lower Deschutes River Benthic Study (DRA 2019) can be found on our website: www.deschutesriveralliance.org.

Our study results are consistent with responses to eutrophic conditions (meaning excess nutrients). In this case the problem is from high loads of nutrients, primarily nitrogen from agricultural sources, and the result is poor water quality. First, our results showed low abundance of pollution sensitive species of caddisflies, mayflies, and stoneflies relative to the abundance of pollution tolerant species like worms and snails. In fact, the abundance of non-insect pollution tolerant species comprised more than 50% of all invertebrates collected from all samples during the study. The results from September 2016 are summarized below.

Deschutes River Alliance benthic sampling results for September 2016. Non-insect taxa (primarily worms and snails), EPT (mayfly, stonefly, and caddisfly taxa), and other (beetles, moths, flies) are expressed as percent relative abundance. Dizney Riffle and Kaskela are at River Mile 99 and 79, respectively, of the lower Deschutes River.

In addition, a polychaete worm was observed in high abundance.  This worm is the intermediate host of the Ceratonova (syn: Ceratomyxashasta parasite and ranged from 252 to over 8,000 individuals per square meter during the study. C. shasta is particularly concerning for the health of spring Chinook salmon in the Deschutes River. The figure below summarizes the complex life cycle of C. shasta.

 

Ceratonova (syn: Ceratomyxa) shasta life cycle. Source: OSU Microbiology department (https://microbiology.science.oregonstate.edu/deschutes-river)

Concurrent studies in 2015 and 2016 by Oregon State University, Oregon Department of Fish & Wildlife, and the US Fish & Wildlife Service detected high concentrations of the C. shasta spores in water samples collected in the lower Deschutes River (see “ODFW Fellowship Report 2015-2016”). Enteronecrosis (aka “gut rot”) is caused by infection of the C. shasta parasite and has caused losses of adult and juvenile Chinook salmon in the Deschutes Basin. The overall effect of this disease on the spring Chinook salmon population is currently unknown but warrants further investigation.

Low numbers of pollution-sensitive insects coupled with high abundance of parasite-hosting non-insect species continue to raise questions about water quality in the lower Deschutes River. Multiple lines of evidence now point toward the Selective Water Withdrawal Tower as the reason for the shift to eutrophic conditions in the lower Deschutes River. The Deschutes River Alliance continues to advocate for the return of cold and clean water to the lower Deschutes River in addition to monitoring the impacts of these changes.

A Successful BBQ in Maupin!

A delicious spread of burgers, hot dogs, and more sourced from the great folks at the Maupin Market.

Both the conversations and the music were lively at DRA’s first annual Maupin BBQ at Kaiser Park in Maupin last Saturday, coinciding with National Public Lands Day and the BLM’s volunteer cleanup event. Turnout and determination were high as people came together to celebrate the Wild & Scenic lower Deschutes River and renew their commitment to improve water quality of the river. 

“It isn’t too late to save the lower Deschutes River, if only all concerned will follow the science, at long last,” said Greg McMillan, president of the DRA. “There is a clear path ahead to improve the health of this waterway that provides drinking water, fish and wildlife habitat, and recreational and economic opportunities for our state.” 

The DRA didn’t let a little wind and rain stop us from throwing an awesome party. Despite the weather conditions, the BBQ carried on and the people who joined us had a great time.

The Slippery Rock String Band (with guest harmonica player Rick Hafele!) keeping the party going.

The river celebration was promoted by the Madras Pioneer, Hood River News, The Dalles Chronicle and KBND radio. And it wouldn’t have happened without the support of amazing community members. Food – including some amazing hot dogs – was coordinated by the Maupin Market. The crew at the Deschutes Angler helped run the grill. Freebridge Brewing provided beer and the Slippery Rock String Band kept toes tapping and people dancing. 

Maupin mayor Lynn Ewing, a long-time supporter of DRA’s efforts was in attendance as well as Wasco County Commissioner Kathy Schwartz.

(From left) Maupin Mayor, Lynn Ewing; DRA President, Greg McMillan; and DRA Board Member, Rick Hafele

Before the party, about 20 folks, including several DRA supporters, joined in the river cleanup along the lower Deschutes, picking up litter and detritus. 

(From left) Allison Bechtol, DRA Executive Director Sarah Cloud, and Jacky Pribyl

This was the first DRA event for new executive director Sarah Cloud. 

“I continue to be impressed and encouraged by the amazing community support for DRA and our work for science-based solutions to improve the water quality of the Wild & Scenic lower Deschutes River,” said Cloud. “This was a great event and I’m looking forward to next year when the party will be even larger.”

A family enjoys food and friends in Kaiser Park