60-100 feet below the land surface. Atrazine was detected in 25 of the 27 wells,
metalachlor in 13 and nitrate concentrations were over the drinking water standard in all
27 samples (Yeary, 1990).
-The Department of Agriculture, Trade and Consumer Protection (DATCP) installed
nests of monitoring wells downgadient from irrigated fields on sandy soil at 15 sites in
the LWRV from Prairie du Sac to Bosbobel. The Preventive Action Limit (PAL) for
atrazine (0.35 ppb at the time) was exceeded at 13 of the 15 sites and the Enforcement
Standard (ES) of 3.5 ppb at 7 of the 15 sites (Postle, 1989). Since this initial studv new
groundwater standards were implented in 1991. The wells were resampled several-times
from April to August, 1991. Out of 100 samples taken, 33% of the samples exceeded the
new PAL (0.30 ppb) while 19% exceeded the new enforcement standard (3.0 ppb). In
addition 23% of these samples had metabolite detects but no parent compound (Postle,
-The Wisconsin Geological and Natural History Survey, with funding from the DN-R,
tested 78 wells (mostly domestic wells) from  Prairie du Sac to Boscobel (Cates, et al.
1991). Of the 66 samples for which both parent atrazine and metabolites were
determined, 28 (43%) had detects. Atrazine metabolites were found in 11 (17%) of the
samples when the parent compud, -iwas not present. Other pe ticides were also
detected including metolachlor, alachlor and simazine (Princep). Nitrate concentrations
exceeded the dri"nking water standard in 27 of the 78 (33%) samples taken.
-The University of Wisconsin-Madison Soil Science department has conducted numerous
studies on the Sparta loamy fine sand at a research site near Arena, in the LWVRV. Soil-
column studies showed herbicide movement through the root zone of this soil to be 15 to