Earth Sciences Commons^™

A Colorado River Basin Authority: Opportunity For Sharing River Basin Management And Resources, David H. Getches

Boundaries and Water: Allocation and Use of a Shared Resource (Summer Conference, June 5-7)

32 pages.

Contains references.

Managing The Upper Rio Grande: Old Institutions, New Players, Steven J. Shupe

Boundaries and Water: Allocation and Use of a Shared Resource (Summer Conference, June 5-7)

19 pages.

Determining Pesticide And Nitrate Levels In Spring Water In Northwest Arkansas, T. L. Lavy, B. A. Dehart, John D. Mattice

Technical Reports

Occurrences of pesticides in our nations ground water are on the rise. As states become aware of this problem and begin monitoring programs, incidence of contamination will probably increase. Since the problem of pesticides in groundwater is relatively new, little research has centered on the fate of pesticides after they reach the groundwater environment. In Northwest Arkansas efforts to monitor groundwater for pesticides have been small. Twenty-five springs in Northwest Arkansas were sampled in the fall of 1988, and spring of 1989. Analysis for atrazine, alachlor, metolachlor, diuron, and simazine in spring water was preformed using gas liquid chromatography and …

Susceptibility Of Northern Minnesota Lakes To Acid Deposition Impacts, Clifford J. Twaroski, J. David Thornton, Rick L. Strassman, Patrick L. Brezonik

Journal of the Minnesota Academy of Science

ABSTRACT-lake chemistry surveys indicate a large number of lakes with acid neutralizing capability (ANC) below 200 μeq/L occur in northeast Minnesota where shallow soils over bedrock and exposed rock outcrops predominate, and in moraine areas having rolling to steep topography in north-central and east-central Minnesota. In the Boundary Waters area, lake chemistry is strongly associated with bedrock geology. lakes with ANC <100 μeq/L are associated with granite, basalt, and gabbro formations, while lakes with ANC of 100- 200 μeq/L are associated with slate and greenstone formations. In the rest of the state where soils are deep, landform, soil type, and lake hydrology determine lake chemistry. Most low ANC lakes are found in terminal moraine areas. These lakes are generally small ( <40 ha in area), have limited groundwater inflow, and typically classed as precipitation-dominated seepage lakes. Higher ANC lakes (>400 μeq/L) are often associated with agricultural and residential land uses. Relationships found between ANC and bedrock geology, and between ANC and landform and soils, provided the basis for mapping the distribution of low ANC surface waters in Minnesota. …

County-Based Priority Assessment Methodology For Phasing Of Wellhead Protection Programs, H. O. Pfannkuch, M. E. Campion, D. C. Mccaa, J. M. Palenberg

Journal of the Minnesota Academy of Science

ABSTRACT-Setting priorities to schedule and implement wellhead protection programs for municipal and community drinking water supplies is presented in the framework of a general risk assessment approach. This includes a hazard identification procedure representing the likelihood of contaminants being released to the surface environment, a hydrogeologic vulnerability assessment representing the risk of contaminants entering the groundwater supply, and an impact assessment, strongly linked to the population at risk. A methodology was developed to aggregate information on a county basis for Minnesota. The resulting composite risk index map shows a number of counties in the central part of the state roughly …

Factors Affecting Water-Supply Potential Of The Twin Cities Metropolitan Area Aquifer System, Michael E. Schoenberg

Journal of the Minnesota Academy of Science

ABSTRACT-The Twin Cities aquifer system in Minnesota contains five aquife~s and fou: confining units that together consist of fourteen geologic units. Unconsolidated sand and gravel aqmfers overlie bedrock sandstone and carbonate aquifers. Between 1880 and 1980, groundwater wi_thdrawals have c_aused long-term wate~ level declines of as much as 90 feet in the Prairie du Chien-Jordan aquifer and 240 feet m the deeper Mount S~monHinckley aquifer-the two major sources of groundwater supplies in the ar~a .. The estimated max1mu1:1 continuous withdrawal rate from the aquifer system is about 650 Mgal/d (million gallons per day). This compares with an average daily groundwater …