Illinois Water Survey scientist Scott Meyer brought good news to members of the McHenry County Defenders at its Loyola Conference Center annual meeting Sunday.
Between 1994 and 2011 water levels in McHenry County wells rose about two feet.
He did point out that 1994 was a dry year and 2011 was a wet one, but the stability of the underground water supply–from which all McHenry County water comes–is encouraging.
“The pumping hasn’t overwhelmed the system in a wet year,” Meyer concluded.
“We can be relieved that we’re not pumping so much that the water level has declined from 1994-2011.”
Meyer presented the 1994 results at a meeting of the McHenry County Soil and Water Conservation District in the mid-1990’s.
Nevertheless, long-term trends show the county faces a water supply challenge. (You can find the report here.)
Population projections assumed are those produced by CMAP. (These projections by the Chicago Metropolitan Agency for Planning have been severely criticized here and here for overestimating growth in McHenry County.)
It is no surprise where most of the problems with water supply are centered–in the south and eastern parts of McHenry County.
One of the results of drawing down subterranean water is there is a decrease of surface run-off.
In 2009, an 10.5% decline was observed.
By 2050, assuming the middle usage projection, the groundwater discharge will be reduced 14.8%.
One expert has suggested that it is alright for water discharge to streams, rivers and lakes to be decreased by 10%.
Such a reduction creates a “cone of depression,” which diverts water from steams to the well.
But, one catchment area–Woodstock’s Silver Creek–has 68% of its water being sucked up for public water supply.
Meyer suggested one way to keep to reduction of surface run-off closer to the 10% level was to spread the wells around the county.
The idea of pumping from the less populated areas and piping it to the denser parts of McHenry County has surfaced before.
There is a draw down in the northwestern part of McHenry County, however that has nothing to do with local wells.
Water is being sucked out from as far away as the Milwaukee area from the next to the lowest aquifer.
Through the western part of the County, however, there was a stream or river before the glaciers came.
After the ice disappeared, this valley was filled with sand and gravel.
Water from above is now seeping into the lower aquifer from above as it is drawn down by far away wells.
Meyer pointed to another growing problem–increased salt in the groundwater from snow removal.
Unfortunately, it is saltier most quickly in the most shallow aquifers.
McHenry County Board members Mary McCann and Michael Walkup were in attendance.
Meyer’s report may be found here.