Ultraviolet light may be the answer to addressing high bacteria readings at some Cannon Beach outfalls.
After almost 10 years of sporadic high readings, the city hired an engineering firm to explore ways to redesign the Gower Street and Chisana Creek outfalls to reduce bacteria readings in the water.
This summer saw high readings through the Oregon Beach Monitoring Program and one health advisory issued for the beach. It’s an issue that has drawn ire from environmental groups and perplexed the city for years, given that readings never appeared to have a pattern other than spiking after heavy large rains.
This year, the city again started taking regular water samples from as far east as the Ecola Creek Forest Reserve to the beach to create a baseline, Public Works Director Karen La Bonte said, then purchased a DNA testing tool to confirm whether the bacteria was coming from human waste. All results came back negative except one, which the city attributed to waste going into a drainage ditch from a nearby homeless camp.
“We know now it’s not human feces, which means there’s no infiltration issue from our sewer,” La Bonte said. “It’s a matter of the bacteria from the pipes.”
With human sources ruled out, the city believes bacteria from animal waste and fungi are building up inside the pipes, a majority of which are underground. Engineers are looking at installing ultraviolet light filters at the outfalls, which would kill the bacteria before it goes out to the beach.
The other option would be to open up the pipes and let the stream run through an open system, exposing the runoff to sunlight and accomplishing the same goal.
“We are not as concerned about animal feces as much as human, but that doesn’t address the fact we’re getting sporadic high readings,” La Bonte said. “It’s still causing harmful bacteria in these areas where dogs, kids like to play around.”
Ingesting bacteria-contaminated water can result in illness, according to the Oregon Health Authority.
While installing ultraviolet light filters would be ideal, engineers are studying whether it’s a viable option with the outfall’s configuration. An open system would also most likely require reconfiguration, and could bring other challenges, such as monitoring what kind of waste could fall or collect in open drainage ditches.
Both systems are effective, La Bonte said, but will likely be expensive.
As engineers conduct the study, La Bonte said she is reaching out to the state and working with the Department of Environmental Quality to get grants to cover the project.
“It’s been very much a needle-in-the-haystack problem, which is very frustrating for me,” she said. “It’s a top priority and we are going to do everything we can to address it. We’re not going to let money be a showstopper with the project. It’s too important. We are going to look for all the funding available.”