Modesto police, the Tuolumne River Trust, and a volunteer river clean-up organisation, Operation 9-2-99, cleared out approximately 7,600 pounds of trash from the caves and the surrounding banks, according to CBS13.
Local officials have known that homeless individuals have been digging out caves in the area for more than a year. In November 2022, CBS13 accompanied officials to the site. Reporters at that outlet said the recently cleared-out caves were far more complex than what they had viewed in 2022.
Modesto police worked with members of its HEART Team, park rangers, and other local organisations to notify the people living in the caves that they would be forced to move. The homeless individuals who were moved were reportedly given assistance.
A spokesperson for the city told CBS13 that officials were monitoring the site and would continue connecting homeless individuals with assistance services.
The city's primary concern with the caves is that they — or the hillside they're built into — could collapse during periods of heavy rain, likely trapping and killing anyone inside.
"If one of these were to collapse, it would be devastating," Tracy Rojas, who lives near the site, told CBS13. "This whole thing would come down and go into the water."
Before being cleaned out, some of the caves were fully furnished with bedding, food and furniture. Some drugs and weapons were also found among the makeshift shelters.
"You can see the hooks on the wall where they had bottles and stuff hanging down," Ms Rojas said. "I think there needs to be more emphasis on the homeless. They are at the point where you can see they are desperate."
Chris Guptill, a coordinator for Operation 9-2-99, told CBS13 that "we really don't have a known solution on how to deal with it."
He said that filling in the caves likely wouldn't work, as people could just carve out new caves.
City crews have since placed temporary fencing and caution tape around the area to discourage further use.
California rents are among the most expensive in the nation, and the state has one of the highest rates of homelessness, according to the Public Policy Institute of California.
More than 70 per cent of Californians across the state say housing affordability is a major concern, and more than half of the state's renters spent 30 per cent or more of their household income just on rent.
As of February 2022, 30 per cent of the US homeless population was situated in California.