Some of fires have threatened homes in the area, prompting frustration from many.
"We definitely know that there's a large number of homeless encampments out here and it's something that we're always concerned about when we're working on fires," said Captain Brian Guzzetta with the Riverside Fire Department.
Guzzetta said they're taking up more and more of the department's resources, adding that firefighters respond to the area on a daily basis for some sort of fire.
Over the last few years, the number of river bottom fires in Riverside believed to be caused by the homeless have steadily been increasing. The city saw 14 fires in 2017, 19 in 2018, 21 last year and 22 so far this year.
A vegetation fire burned 70 acres nearly the river bottomand briefly prompted the evacuations of nearby homes on Feb. 6.
"We have residents going to bed every night wondering if this is the night that their house will go up in flames," said Riverside Councilmember Erin Edwards.
Edwards plans to host a town hall meeting on Wednesday to discuss ways to address the problem.
"We can be (trimming) trees, we can be creating fire breaks, taking out non-native plant species to make sure that the river bottom isn't full of the fuel that will burn," she said.
Riverside police say they try to clean the area every few weeks but the encampments keep coming back.
"If we're thinking about addressing the problem of homelessness, which I certainly am, that will take many types of solutions," Edwards said.