Date of this Version
The City of Lincoln draws water from a well field along the banks of the Platte River near Ashland. Since 1989 we have monitored the infusion of atrazine into this well field via recharge from the Platte River. Samples of water from the river, several monitoring wells and production wells were analyzed by gas chromatography coupled to mass spectrometer following solid phase extraction. Atrazine concentrations were found to be less than 0.1 ppb before the growing season every year through 1989-1992. Atrazine in the Platte reached maximum concentrations of 5, 11, 19, and 19 ppb respectively in these years. These increases corresponded to precipitation events and agricultural practices in the Platte River basin. Following a time delay, high concentrations were observable in the well water samples and ultimately in Lincoln municipal tap water.