The Colorado River in the Yuma area has tested high for selenium, and the state is asking the city to find the source and eliminate it.
Yuma is regulated under an Environmental Protection Agency permit, which has the ultimate goal of protecting surface waters from polluted stormwater runoff. In Yuma’s case, that surface water is the Colorado River.
In 2016, the Arizona Department of Environmental Quality declared the river from the Yuma Main Canal to the Mexico border an impaired water due to high selenium and low dissolved oxygen.
In 2018, the dissolved oxygen was removed, and “we no longer have to worry about that,” City Engineer Jeff Kramer recently told the city council.
“But high selenium is still an issue for us,” he added.
Selenium is a naturally occurring mineral that comes from soil runoff. “It does have some pretty disturbing possible side effects of toxicity,” Kramer said, noting that it can cause hair and nail loss, tooth decay and decreased mental acuity.
“So we definitely want to try to prevent selenium in the water,” he said.
To do that, the city has taken several steps, including delineating the drainage area with the highest potential of discharge into the river and reducing and preventing discharge of pollutants from construction and post-construction sites into river.
The “big one” was introducing a surface water monitoring program that looks at specific points where water discharges into the river. The priority area goes from the Third Street and Giss Parkway alignment to the river and extends from 22nd Avenue to Gila Street. The points with the highest potential for discharge into the river within that area are 19th, 17th, 9th and Madison avenues.
To prevent pollutants from entering the river in those areas, the city cleans the storm drain system in a collaborative effort with the engineering, utilities and public works departments. The whole system is cleaned every three years.
The ADEQ approved the city’s monitoring program in June 2016, making Yuma the first “small municipality” in Arizona to perform stormwater testing. The testing began in 2017 and has cost $1,950.
In that time, the city has found seven exceedances for selenium, four at the “trouble spot” of Madison Avenue, although each point has had at least one exceedance.
The city may have to start upstream testing to try to determine the source of the pollutant and where the selimum is entering the system. In some cases, multiple city and county storm drainage combines together.
“So we don’t know if that selenium concentration is coming from the city-generated discharge or the county, or a combination of the two,” Kramer said.
The city is watching over two types of operations, discharge from operations controlled by the city, such as street sweeping and slurry sealing, and runoff from private development, which is still under city oversight.
At construction sites of one acre or more, Yuma requires the owner to implement the Stormwater Management Program, which means developing plans to prevent stormwater pollution from leaving the site.
After Kramer’s presentation, Councilwoman Karen Watts questioned if anything can be done once selenium is in the water. “I don’t know the answer. Our responsibility is to try to prevent it from getting into the river. The goal is for us to eliminate where it’s coming from so eventually it will dilute itself out and drop below the impairment level,” Kramer said.
Watts also asked if the selenium affects the water used to water crops. “Not that I’m aware of,” Kramer said.
Councilman Mike Shelton noted that selenium is a very popular supplement. He asked: “What is the difference between supplements and the one that goes in the water?” Kramer replied: “I don’t know, not being a medically trained person. My assumption is the concentration.”
Councilman Edward Thomas asked if the city is not responsible for the selenium output, then why it is being held accountable for it. “The issue is we don’t know where it’s coming from, what the source is. That’s why the upstream monitoring might be useful. Then perhaps we can identify the source,” Kramer said.
The Engineering Department website will be updated to provide a detailed stormwater page. Anyone can report stormwater violations or concerns by calling 928-373-4520 or emailing to firstname.lastname@example.org.