In June 1945, a weedicide maker in Alhambra poured toxic waste substances into his floor drain. The weed killer passed through the sewage treatment plant unchanged and then entered the Rio Hondo River. From there, it was carried into the coastal plain and, although diluted, soaked into the underground aquifer used by the City of Montebello. This contaminated at least 11 water wells providing water to 25,000 people then living in South Montebello. Despite expensive efforts to clean the polluted water, users continued to endure bad taste and odors for about five years. This incident dramatically increased the urgency for state legislation to regulate industrial waste disposal and groundwater protection. It resulted in California's landmark Dickey Water Pollution Act of 1949 (spearheaded by Alameda County Assemblyman Randall Dickey), making sweeping changes to state laws relating to water quality and water pollution and becoming California's first comprehensive water pollution act.