ATRAZINE IN A STREAM-AQUIFER SYSTEM - TRANSPORT OF ATRAZINE AND ITS ENVIRONMENTAL-IMPACT NEAR ASHLAND, NEBRASKA

Lincoln's municipal wellfield consists of 44 wells located adjacent to the Platte River near Ashland, Nebraska. The herbicide atrazine was m onitored in the river and two transects of monitoring wells. The amoun t of atrazine transported down the Platte River in 1989, 1990, and 199 1 was shown to increase each year. Induced recharge from the Platte Ri ver results in movement of atrazine from the river into the aquifer. A 21-day lag time was determined for the movement of atrazine from the river to a transect of monitoring wells 10 feet west of the bank. The role that colloids play on the transport of atrazine was determined to be insignificant. A small percentage of atrazine found in the river w as determined to come from rain water. The infiltration of agrichemica l-contaminated river water was shown to significantly reduce the quali ty of raw water and finished water being produced by the adjacent aqui fer.