Report: NASA technology detects Tijuana River pollutants

NASA technology originally intended for mapping minerals in desert regions can analyze pollutants present in the Tijuana River sewage plume near Imperial Beach, scientists said.

A paper published in the journal Science of the Total Environment says that satellite images have shown a large wastewater plume at the mouth of the river. Contaminated water can harm people, marine ecosystems and local wildlife, and the environmental issues unfolding in the Tijuana River Valley are associated with ongoing health concerns for its residents.

“The science is clear, the health risks are real, and seeing it all from space satellites just underscores what South County families are being forced to endure,” said Imperial Beach Mayor Paloma Aguirre in a statement.

The Tijuana River enters the Pacific Ocean just south of Imperial Beach and near the United States-Mexico border. The river contains millions of gallons of both treated and untreated sewage, which has been a growing cause for major concern for its residents in recent years.

Satellite technology has been used for years to track algae blooms, the vibrant reds and greens being easy to spot from outer space. But pollutants and bacteria can be much harder to identify.

The Earth Surface Mineral Dust Source Investigation, or EMIT, measures light and analyzes the wavelengths that can indicate different mineral compositions. 

This technology essentially allows scientists to analyze satellite images and decipher which minerals, bacteria and pollutants are present — in this case, in the Tijuana River. 

EMIT’s observations, coupled with samples tested from the ground at the Tijuana River, found the presence of cyanobacteria, an organism that can negatively affect the health of humans and animals alike if ingested or inhaled. Symptoms of cyanobacteria exposure include nausea, headaches, lethargy, numbness, drowsiness, and even death.

The NASA report was published on June 12, and Aguirre said it serves as a “flashing red alert,” while also asking the county to “stop sitting on the sidelines and start investing in the basic infrastructure we need to protect our air, water and health.”

“From orbit you are able to look down and see that a wastewater plume is extending into places you haven’t sampled,” said Christine Lee, a scientist at the Jet Propulsion Laboratory in Pasadena and a coauthor of the NASA study.

Launched in July 2022, EMIT was originally designed solely for mapping minerals in desert regions. However, EMIT may now be used to analyze water, in a development that would allow beachgoers and scientists alike to stay up to date on water pollution without field samples.

According to Eva Scrivner, the lead author of the NASA report, the EMIT Tijuana River findings show “a ‘smoking gun’ of sorts.”

Scrivner also said the EMIT development could be good for filling in data gaps rather than using traditional water sampling methods that tend to be time-consuming and costly.

While EMIT might provide more answers and insight down the line related to pollution in the Tijuana River, the wastewater crisis is still ongoing.

Aguirre, who is also running for county Supervisor in a special election, criticized the actions of San Diego County politicians thus far on the issue.

“If the county can’t take serious action on a sewage crisis we can see from outer space, maybe it’s because the county politicians downtown are living on another planet,” Aguirre said.