By Adriana Barrera
MEXICO CITY (Reuters) - A Mexican state has launched an investigation to determine the source of heavy metals and organic matter polluting a river that feeds what was once a spectacular water fall.
Patricia Martinez, who heads Jalisco Territory Management, a state agency overseeing the river cleanup efforts, told Reuters this week that the government was seeking federal help to determine which factories were responsible.
She said samples showing levels for some heavy metals and pollutants above the legally defined limits did not conclusively show which companies were responsible.
The Santiago river has been a backbone of economic growth in Jalisco, a western state that is a major producer of farming products, the birthplace of Tequila, and also home to vibrant chemical, manufacturing, automotive and food industries.
The river and the Juanacatlan waterfall, once a tourist attraction and a source of clean drinking water known as Mexico's Niagara Falls, is now foul-smelling and capped with thick foam. Local residents, environmental organizations, and investigators say it is a source of disease.
Mexico's weak environmental laws and enforcement were a focus in negotiations for a new regional trade deal between Mexico, the United States and Canada (USMCA), with U.S. Democrats arguing lax rules were an unfair competitive advantage.
Jalisco's government recently sampled water at 150 different points along the river, state environment secretary Sergio Graf told Reuters.
As a result of the tests, the state last week unveiled a plan seeking to reduce pollution from waste runoff, including heavy metals and organic matter, and presented a list of 29 companies under scrutiny.
There will be "zero tolerance," Jalisco governor Enrique Alfaro said last week after a tequila plant was shuttered as part of the strategy to clean up the river.
"We want there to be investment in Jalisco, we want to encourage investment, but we want the investment generated in our state to be environmentally friendly and to assume its responsibility and comply with the law," he said.
The Juanacatlan waterfall is now "a source of pollution, not only for the local population, but for those who visit it and those who live nearby," the Jalisco government said on a website dedicated to the river cleanup, citing a government study.
The contamination "is associated with many types of health problems," said the website, citing another study.
(Reporting by Adriana Barrera; Additional reporting by Sharay Angulo in Mexico City and Jose Luis Osorio in Juanacatlan; Writing by Anthony Esposito; Editing by Rosalba O'Brien)