SAN RAFAEL, California, April 11 (Reuters) - As the COVID-19 pandemic wanes, a California county is using the same wastewater monitoring program it used to track the coronavirus to go after another deadly public health crisis: opioids. Marin County, north of San Francisco, began a pilot program in February to collect wastewater samples from its sanitation agency and test them for the presence of substances like fentanyl, methamphetamines, cocaine, and nicotine. Local authorities hope the data could be beneficial in assisting prevention and intervention efforts. For example, if there is an abundance of opioids present in the samples, they could boost the distribution of Narcan, which rapidly reverses the effects of the illegal drug, especially when given within minutes of the first signs of an overdose. "The problem of overdose is a public health crisis. We're losing one resident every five days in Marin County," said Dr. Matt Willis, Marin County's public health offic