By Alex Dobuzinskis
LOS ANGELES (Reuters) - A massive sewage spill from Mexico's Tijuana River that polluted miles of coastland in Southern California and northern Mexico has prompted an investigation, with U.S. officials calling it deliberate and Mexican authorities saying it was an accident caused by heavy rain.
The pollution closed beaches and kept surfers and swimmers out of the ocean, drawing outrage from residents of the cross-border region.
Tensions are running high between Mexico and the United States after U.S. President Donald Trump promised to build a border wall, deport millions of Mexicans in the United States illegally and tax Mexican imports.
U.S. officials, including Imperial Beach Mayor Serge Dedina, believe the spill was deliberate to cut corners during repair work on a sewer pipeline in Mexico but not politically motivated.
"It was intentional," Dedina said by phone from the California city near the Mexican border. "The big picture is we need to work to support Mexico's effort to improve the sewage infrastructure system in Tijuana so this doesn't happen again."
A spokeswoman at the Tijuana State Public Service Commission said the spill was an accident that resulted from heavy rains collapsing a sewage interceptor in the city, adding that they notified the International Boundary and Water Commission, a joint U.S.-Mexico agency.
The commission, which is leading the investigation, was notified on Feb. 23 but U.S. officials believe the spill started at least two weeks earlier and dumped roughly 143 million gallons (541 million liters) of sewage into the Pacific Ocean, said Lori Kuczmanski, a spokeswoman for the U.S. section of the commission.
Contact with raw sewage can cause serious infections and illnesses such as diarrhea.
The sewage spill polluted 20 miles (32 km) of coastland from the areas of Rosarito in Mexico to Coronado in California, Dedina said.
U.S. Representatives Juan Vargas and Scott Peters, who represent the San Diego area, on Wednesday submitted a letter to the U.S. Secretary of State and the director of the Environmental Protection Agency asking for federal actions to prevent any similar occurrence.
(Reporting by Alex Dobuzinskis; Additional reporting by Lizbeth Diaz in Mexico City; Editing by Patrick Enright and Lisa Shumaker)