Laserfiche WebLink
• <br />Minnesota Baseline Water Quality of <br />Pollution <br />Control <br />Agency <br />Environmental <br />Outcomes <br />Division <br />Ground Water <br />Monitoring & <br />Assessment <br />Minnesota's Principal Aquifers: <br />Region 6, Twin Cities Metro Area <br />What was the baseline study? <br />Between 1992 and 1996, the Minnesota <br />Pollution Control Agency's (MPCA) <br />Ground Water Monitoring and <br />Assessment Program (GWMAP) <br />sampled 954 primarily domestic wells <br />across Minnesota. The goal of this <br />study, called the baseline study, was to <br />determine ambient water quality in <br />Minnesota's principal aquifers. <br />What parameters were sampled? <br />Each well was sampled for 48 inorganic <br />chemicals such as nitrate, chloride, <br />arsenic and metals; 68 volatile organic <br />compounds (VOCs), such as benzene; <br />other parameters, such as pH and <br />temperature; total dissolved solids and <br />total organic carbon. In addition <br />selected wells were tested for tritium, an <br />indicator of water less than 50 years old. <br />What is Region 6? <br />The MPCA has divided Minnesota into <br />six regions. Region 6 encompasses the <br />Twin Cities Metropolitan Area and <br />includes the counties of Anoka, Carver, <br />Dakota, Hennepin, Ramsey, Scott and <br />Washington. The regional office is in <br />St. Paul. <br />How many wells were sampled and in <br />which aquifers? <br />In 1993, 1994 and 1996, 93 wells were <br />sampled in Region 6. Of these 93 <br />GWMAP, March 1999 <br />samples, 25 were from wells completed <br />in buried confined sand and gravel <br />aquifers, 10 were from wells completed <br />in surficial sand and gravel aquifers, one <br />was from a well completed in a <br />Precambrian aquifer, and 57 were from <br />wells completed in Paleozoic bedrock <br />aquifers. <br />What is the quality of ground water in <br />Region 6? <br />Water quality varied among the major <br />aquifers of Region 6. The Franconia <br />aquifer had high concentrations of many <br />chemicals compared to other aquifers in <br />the region, particularly for the major <br />ions. The Prairie du Chien aquifer is <br />sensitive to human activity, as evidenced <br />by elevated nitrate and chloride <br />concentrations. The Jordan aquifer has <br />good - quality water, with low <br />concentrations of dissolved solids <br />compared to other aquifers. Water <br />quality in the St. Peter aquifer varied <br />widely, with half the samples showing <br />impacts from human activity. The <br />surficial drift aquifers showed impacts <br />from humans, with concentrations of <br />chloride, sodium and some trace metals <br />being high compared to other aquifers. <br />The number of exceedances of drinking <br />water criteria are shown in the table on <br />the back of this fact sheet. There were <br />few exceedances of drinking criteria, but <br />this may be related partly to sampling <br />Minnesota Pollution Control Agency, 520 Lafayette Rd. N., Saint Paul, MN 55155 -4194 <br />(651) 296 -6300, toll -free (800) 657 -3864, TDD (651) 282 -5332 or (800) 657 -3864 <br />This material can be made available in altemative formats for people with disabilities. <br />PrintMri nn ranvr.Iarl nanar rnntaininn at Iaact 20 narr:Ant fihar¢ from nanAr ranvrlarl by norm Imarr <br />