The shoreline of an oceanfront California city has been strewn with raw sewage from two treatment plants along the U.S.-Mexico border for years, closing the local beach, raising serious health concerns and bringing a pervasive stench "akin to being trapped in a portable toilet," according to a report.

The putrid problem in Imperial Beach, a city of some 26,000 people about 10 miles south of San Diego, isn't new, with concerns about contamination from the nearby Tijuana River dating back nearly a century, according to CBS News.

But it does seem to be worsening.

Over the last five years, some 100 billion tons of raw sewage have flowed from the river and to the city's coast, bringing a host of environmental and health hazards, the outlet reported.

Researchers from San Diego State University's School of Public Health called the condition a "public health crisis" in issuing a report last month that noted the presence of heavy metals, toxins and bacteria including E. coli in the water.

"It's the worst smell," local Shannon Johnson told CBS. "It gets into your lungs. It gets into your clothes. It's disgusting."

The stench stems from two nearby wastewater plants, one on either side of the U.S.-Mexico border.

One, the South Bay International Wastewater Treatment Plant, sits in San Diego County but was built in the 1990s to accommodate sewage from Baja California, Mexico.

But the Mexican state's growing population has left the plant struggling to keep pace, and the facility is underprepared to withstand extreme weather, CBS reported.

Mexico recently committed a cumulative $83 million to updating that facility and the other, Tijuana's San Antonio de los Buenos Wastewater Treatment Plant. That's in addition to investments made with U.S. tax dollars.

The contamination has led to the city's beach being closed for over 700 consecutive days, as of CBS' Saturday report.

Johnson said that her children, ages 9 and 10, attend school near the city's river valley, where the smell can be particularly overpowering.

"They're like, 'Why is it so smelly? Is it safe?'" Johnson told CBS. "I'm like, yeah, I guess so. What am I supposed to tell them?"

Many of Johnson's neighbors are asking the same questions.

In a batch of letters compiled by another fed-up local, Marvel Harrison, to implore local lawmakers for help, one resident said the odor was "akin to being trapped in a portable toilet."

The inescapable smell has left some, like Harrison, thinking about pulling up stakes.

"I find myself looking at other places we might be able to live," Harrison, 67, told CBS. "And that's really disheartening given that this is where and how we wanted to be in retirement."