Claim: The sewage issue in the Tijuana River is considered a cross-border problem between the United States and Mexico.
Verdict: Correct (95% confidence)
Explanation: According to the U.S. Environmental Protection Agency (EPA), untreated raw sewage has been flowing from Mexico into Southern California, polluting the Tijuana River Valley and affecting both countries (epa.gov). The California State Lands Commission also confirms that transboundary flows from Mexico into the United States occur regularly due to inadequate water infrastructure (slc.ca.gov). Additionally, SD Coastkeeper describes the sewage issue as a complex cross-border problem involving both th...