Thirty percent of groundwater organizations cite nitrate contamination as a groundwater quality concern. Nitrates can come from animal manure and chemical fertilizers that leach into groundwater.
When groundwater pumping exceeds the volume of groundwater recharge, the concentration of contaminants like nitrates can increase. Nitrate contamination is a concern on more than half of the groundwater-fed irrigated acreage within groundwater organization service areas.
USDA’s Survey of Irrigation Organizations collected information on the estimated 735 local entities that manage on-farm groundwater use through statutory, regulatory, or other powers. While nitrate contamination was the most common groundwater quality concern reported, contamination by salinity, other nutrients, and heavy metals are a concern for 27, 19, and 18 percent of groundwater organizations, respectively.
Contaminated groundwater can harm crops or make the water unusable for irrigation entirely.