TY - GEN
T1 - Dye tracing within the St. Lawrence confining unit in Southeastern Minnesota
AU - Green, Jeffrey A.
AU - Luhmann, Andrew J.
AU - Peters, Andrew J.
AU - Runkel, Anthony C.
AU - Alexander, E. Calvin
AU - Alexander, Scott C.
PY - 2008
Y1 - 2008
N2 - Southeastern Minnesota's karst lands support numerous trout streams. These trout streams are formed by springs discharging from Paleozoic bedrock. Dye tracing has been the tool of choice for mapping the springsheds (karst groundwater basins) that feed these springs. Previous work was focused on the Galena limestone karst. In order to accelerate springshed mapping, a two-year study was funded by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR). Across southeastern Minnesota, numerous springs discharge from the Cambrian St. Lawrence formation. The St. Lawrence is considered to be a confining unit under the Minnesota well code. A dye trace was initiated when a stream sink was discovered in the upper St. Lawrence Formation. The sampling points included springs, stream crossings, and a municipal well that may be at risk for surface contamination. Dye was recovered at one spring in less than two weeks and at two other springs in less than three weeks. This translates into travel times of 200-300 meters/day. The springs all discharge from the lower St. Lawrence Formation. The St. Lawrence contains beds of dolostone; the dye trace demonstrates that there is a karst conduit flow component in this formation. This is evidence that these springs are significantly more susceptible to degradation than previously thought.
AB - Southeastern Minnesota's karst lands support numerous trout streams. These trout streams are formed by springs discharging from Paleozoic bedrock. Dye tracing has been the tool of choice for mapping the springsheds (karst groundwater basins) that feed these springs. Previous work was focused on the Galena limestone karst. In order to accelerate springshed mapping, a two-year study was funded by the Minnesota Environment and Natural Resources Trust Fund as recommended by the Legislative-Citizen Commission on Minnesota Resources (LCCMR). Across southeastern Minnesota, numerous springs discharge from the Cambrian St. Lawrence formation. The St. Lawrence is considered to be a confining unit under the Minnesota well code. A dye trace was initiated when a stream sink was discovered in the upper St. Lawrence Formation. The sampling points included springs, stream crossings, and a municipal well that may be at risk for surface contamination. Dye was recovered at one spring in less than two weeks and at two other springs in less than three weeks. This translates into travel times of 200-300 meters/day. The springs all discharge from the lower St. Lawrence Formation. The St. Lawrence contains beds of dolostone; the dye trace demonstrates that there is a karst conduit flow component in this formation. This is evidence that these springs are significantly more susceptible to degradation than previously thought.
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U2 - 10.1061/41003(327)45
DO - 10.1061/41003(327)45
M3 - Conference contribution
AN - SCOPUS:66649083739
SN - 9780784410035
T3 - Geotechnical Special Publication
SP - 477
EP - 484
BT - Proceedings of the 11th Multidisciplinary Conference - Sinkholes and the Engineering and Environmental Impacts of Karst, GSP 183
T2 - 11th Multidisciplinary Conference - Sinkholes and the Engineering and Environmental Impacts of Karst
Y2 - 22 September 2008 through 26 September 2008
ER -