The California State Water Resources Control Board will soon set a maximum contaminant level for 1,2,3 Trichloropropane, or 1,2,3 TCP.

It’s found in industrial solvents and cleaning agents, but it was once found in two popular soil fumigants made by Dow Chemical and Shell Oil Company.

The pesticide byproduct contaminated groundwater throughout the Central Valley. State water regulators have found 1,2,3 TCP in 94 public drinking water systems in 16 counties.

Right now, water systems in California are only required to notify residents if the chemical is found at a certain health-based advisory level.