National Water-Quality Assessment (NAWQA) Program - South Platte River Basin
Pesticides in Surface Water During the Irrigation
PAST SURFACE-WATER ACTIVITIES
Map and Data for This Study
Examine the occurrence and distribution of pesticides near and
along the South Platte River during the irrigation season (pesticide
Sampled 19 sites at the mouths of major tributaries and along the
main stem South Platte River from Henderson, Colo., through North
Platte, Nebr. Two to three samples were collected at each site,
during both high and low flow conditions.
- Targeted Physical and Chemical Data:
Flow, pH, specific conductance, dissolved oxygen, water temperature,
- Selected Results:
39 pesticides were detected at least once. Concentrations generally
were less than standards or guidelines for drinking water and aquatic
Only 8 of the 39 pesticides detected had median concentrations greater
than their respective detection limits.
The herbicide DCPA (commonly used for irrigated agriculture) was
measured at the highest concentration of 30 micrograms per liter.
Atrazine (commonly used for irrigated agriculture) and prometon (commonly
used for long-term weed control in noncropped areas) persisted throughout
the growing season at consistent concentrations.