What Is a Maximum Contaminant Level?

The US National Water Quality Assessment Program reported that more than 95% of streams and nearly 50% of shallow wells were found to contain agricultural pesticides. Only about 10% of organic farms use pesticides on a regular basis. Most organic farmers don't use any pesticides at all or only very small amounts. The EPA has set maximum content levels for a whole bunch of different pesticides so that determination is made about whether or not it's harmful.