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Draft North& East Metro Groundwater Management Area Plan 4-5 Based on observation well levels, lake levels, and stream gauging data, the 1990s to early 2000s was a wet period in this region with relatively high water levels and flows. The period 2007 through 2013 included at least one period of hydrologic drought.This determination is based on a comparison with measured water levels and stream flows during and following the last extreme drought in the region (1988-899) at locations with low water use10. Relatively low water levels were most prevalent in groundwater and surface water measurements reflective of groundwater conditions such as stream baseflow. Figure 4-3 is one example of the gradual fluctuations in groundwater levels in a 'nest' of observation wells open to several different aquifers at different depths in northeastern Washington County. This obwell nest is four miles from the nearest municipal well and there is little other groundwater use in the vicinity. Water levels gradually declined in these observation wells from 2003 through 2010 and remained low through 2013. Water levels in the shallower obwell (82024) dropped below the minimum level of the previous extended drought that occurred in 1991, and water levels in the deeper obwells overlapped with levels previously measured in 1990-91 from 2009 through 2013. � 830 - - 825 i 820 -- - — ---- -- - — —— -- 815 N 810 --82024(Buried Artesian) 4 805 -- — -- — ----- S? 800 ---82023(Buried Artesian) °> 795 — ,-82022(Tunnel City-Wonewoc) w -- -- - - - -- - - -w'r --- ---- ai 790 785 - - -- � �— {j( --- --- — •- - "X% v . -r - --- 780 775 -- --- - -- -----1— --- W.80 Dec.84 Jan-90 3an-95 Dec-04 10 15 i Jan Jan-10 4-3 Observation well hydrographs, northeastern Washington County The three observation wells are completed in three different aquifers: a shallower buried Quaternary aquifer (82024), a deeper buried Quaternary aquifer in a bedrock valley(82023) and a bedrock aquifer (82022). Seasonal water level fluctuations have increased in the buried Quaternary and bedrock aquifers in areas of intensive groundwater pumping. Seasonal fluctuations at these locations increased due to 9 Some of the effects of this drought are described in: Minnesota DNR, 1989.Drought of 1988;and in Holmstrom and Ellefson, 1990. The Effects of the 1988 Drought on Water Resources in Wisconsin:USGS Open-File Report 90- 149. to Data sets used: DNR observation wells 13007/18, 13009/13, 82024,82031,and 82033; North Center Lake; Wisconsin USGS observation well PK-35/17W/08-0040(USGS Station 453013092314601);Apple River near Sommerset,Wisconsin (USGS Station 05341500);and St. Croix River at St.Croix Falls,Wisconsin (USGS Station 05340500) P63