Hydraulic Conductivity of Near-Surface Alluvium in the Vicinity of Cattlemans Detention Basin, South Lake Tahoe, California

Cattlemans detention basin, South Lake Tahoe, California is designed to capture
and reduce urban runoff and pollutants originating from developed areas before
entering Cold Creek, which is tributary to Trout Creek and to Lake Tahoe. The
effectiveness of the basin in reducing sediment and nutrient loads currently is
being assessed with a five-year study. Hydraulic conductivity of the alluvium
near the detention basin is needed to estimate ground-water flow and subsurface
nutrient transport. Hydraulic conductivity was estimated using slug tests in 27
monitoring wells that surround the detention basin. For each test, water was
poured rapidly into a well, changes in water-level were monitored, and the
observed changes were analyzed using the Bouwer and Rice method. Each well was
tested one to four times. A total of 24 wells were tested more than once. Of
the 24 wells, the differences among the tests were within 10 percent of the
average. Estimated hydraulic conductivities of basin alluvium range from 0.5 to
70 feet per day with an average of 17.8 feet per day. This range is consistent
with the sandy alluvial deposits observed in the area of Cattlemans detention
basin.

[Summary provided by the USGS.]