The Department of Agriculture, Trade & Consumer Protection (DATCP) has conducted several surveys of pesticides in groundwater and has consistently found atrazine to be the most commonly detected pesticide in groundwater. A survey of randomly selected Grade A dairy farm wells in 1989 detected atrazine in 12% of the wells tested. As of December 2001, over 23,000 private water wells have been tested using an immunoassay triazine screen. Thirty-seven percent of these samples have had triazine detected.