By Jess Winans

Aerator devices to be placed in Mission Valley section of San Diego River

On Saturday, Aug. 11, the San Diego River Park Foundation (SDRPF) held an open house-style event showcasing new aerator devices placed in the section of the river trail near 2107 Qualcomm Way.

“In the summertime, when there’s not a lot of flow in the river, the oxygen in the river gets really low,” said SDRPF Assistant Director Sarah Hutchmatcher. “Dissolved oxygen is a really important water quality component. The bugs and the fish and all of the different things in the river rely on the water to get their oxygen.”

Without a significant amount of dissolved oxygen in the river, its inhabitants begin to die off, causing an unpleasant smell for nearby residents, walkers and river-goers.

Like a spa jet in your hot tub, the aerator devices blow bubbles into the water. The aerators are powered by 60-watt or 250-watt solar panels, the wattage depending on their size.

“It’s a jet that’s pulling the water up then exiting it laterally, creating bubbles and moving the water like a jet in the spa,” said SDRPF River Ecosystems Manager Shannon Quigley- Raymond. “The pumps are super quiet and the rotations per minute are less than that of a stationary bike, so [the aerator devices are] not loud or disturbing to birds or anybody by the river.”

Last year, SDRPF was awarded a $154,000 grant from the San Diego River Conservancy for the aerator devices as part of a pilot program. The devices themselves cost between $10,000 and $20,000, leaving the foundation room to use the surplus funds from their grant for educational purposes.

Each device was installed by volunteers on kayaks. They are each paired with their own floating data logger that uses a memory card to measure the river’s temperature and dissolved oxygen levels in 15-minute intervals. Foundation volunteers go out onto the river every other Thursday along with some students from San Diego State University to analyze the data using graphs.

“Our project is at an area of the river where you can’t usually get on boats, so [volunteering on the project is] kind of a fun chance to get out on the water,”  Hutchmatcher said, “A lot of our volunteers really talk about how enjoyable it is to get away from the road noise and just float away on the river.”

Collectively, the devices took 474 volunteer hours to install; and where SDRPF works with around 7,000 volunteers a year, Hutchmatcher said around 100 have helped with this particular project so far.

In the future, Hutchmatcher and Quigley-Raymond hope to have volunteers actively manage the Mission Valley section of the river to prevent homeless encampments — an issue brought up by a resident at the Aug. 11 event.

“Homeless encampments are one of the largest issues that we face for dealing with trash on the San Diego River,” Hutchmatcher said. “ In the recent years, it has been as much as 97 percent of trash that we clean up is related to encampments. Most recently that number went down to about 85 percent but it’s still a pretty significant contributor. We’re picking up 300,000 pounds of trash, so 85 percent is still hundreds of thousands of pounds of trash that’s coming from encampments.”

The river aeration project may also help keep homeless camps away from the river.

“What we find with the homeless people — people who interact with homelessness that live along the river — they’re looking for a place to hide,” Quigley-Raymond added. “If a place is more active then that might not be the place that is ideal for them. We find areas that have rangers and active patrols going through don’t have the same occurrences of encampments as a place that maybe the land management method might be more passive.”

The aerators are not set to be installed until November of this year, and SDRPF is always looking for volunteers.

“Joining our water quality team is a really cool opportunity for people to get a little bit of technical experience,” Hutchmatcher said. “Some of our volunteers are professional scientists who know a lot about water quality and how to do this kind of project design. Some of them are college students or graduate students who are looking to get out in the field, and then some of them are first-timers who are just like, ‘Tell me what to do!’ It’s a really big mix.”

SDRPF is also looking for community members to take a survey involving dissolved oxygen. To take the survey visit bit.ly/SDRPFSurvey and for more information on the San Diego River Park Foundation, visit sandiegoriver.org.

 —Jess Winans is the editorial assistant for SDCNN, parent company of Mission Valley News. Reach her at [email protected].