|This map shows the generalized water service areas in the valley in relationship to the LPRV aquifer. The most important wells in each service area are indicated. The pattern shown is for summertime use conditions, when almost all municipal wells are pumping. In winter, when demand drops substantially, the pattern changes slightly according to which wells are turned off.|
|Recall that, similar to surface drainage,
the Lower Portneuf River Valley aquifer is divided from the upper aquifer by the Portneuf
Gap bedrock upthrust. In addition, the LPRV aquifer is further subdivided into four
regions based on differences in local subsurface geology (both in terms of mineral
composition and structure) in the different reaches. The four divisions and their
dominant characteristics include the:
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The geologic differences described above mean that the four sub-aquifers also differ from one another in terms of their producing capacity, water chemistry, vulnerability to pollution from surface activities and more. (Because water moves through the aquifer's pore spaces it is in direct contact with the geologic matrix comprising the aquifer and acquires a corresponding water chemistry, while surface water percolates downward into the aquifer, coming into contact with any compounds or objects in its flowpath.) Ultimately, this means that the exact quality of the water flowing from your tap will vary depending on what subaquifer your municipal supply well is drawing from.
Look at a diagram that shows the four LPRV aquifer subdivisions and their relationship to the aquifer as a whole. The location of the Portneuf Gap is shown in the figure, as are the major geologic cross-sections that have been used to characterize the subsurface hydrogeology of the lower Portneuf valley. The numbers indicate the location of municipal wells that are extracting water from the correlating subaquifer below. Use this figure in conjunction with the map above to gain a general understanding of which well(s), and hence which subaquifer, you would expect to obtain your water from in the summer. Because of the proximity of a number of wells, they have been grouped into service areas (indicated by colored shading). If you live in an area of overlap between service areas, you could expect to receive a mixture of water from wells in adjacent service areas.
Find your geographic area on the map above, then