A new Illinois State Water Survey study says what a multitude of studies before it have concluded – McHenry County’s groundwater supply could become a big problem over the next decades.
In a 242-page report released Tuesday, the survey team led by hydrogeologist Scott Meyer concluded that, if left unchecked, groundwater resources by 2050 could be strained to the point of water shortages and adverse effects on rivers, streams and wetlands.
“How much groundwater is available to users in McHenry County long-term – that is, the sustainable pumping rate – depends on how groundwater withdrawals affect the environment and what the public considers to be acceptable environmental impacts,” the report states.
McHenry County is entirely dependent on groundwater for its water supply. Existing limits on how much water can be drawn from Lake Michigan, to say nothing of the cost, make the avenue taken by municipalities in Cook and the other collar counties highly improbable.
County wells pumped an average of 24.7 million gallons a day in 2009, according to the report. Depending on growth and use practices, that amount could increase by 2050 to between 31.5 and 67.9 million gallons a day – an increase of 6.8 percent in the best-case scenario to 175 percent in the worst.
Meyer and his colleagues mapped water levels from 329 county wells in 1994 and again in 2011, and built a computer model to simulate groundwater flow from more than 8,700 wells. Some of that data came from a network of 40 or so monitoring wells the county had drilled in 2008 for exactly this purpose. The county and the federal government split the $590,000 cost.
Simulations in the report suggest that problems could arise as soon as 2030, particularly in the county’s heavily-populated southeast. By then, drawdown in deep-aquifer wells could be significant enough to prevent those wells from providing the amounts of water expected if they are not drilled deep enough. But wells in shallow aquifers, which provide more than 70 percent of the county’s water supplies, also could suffer shortages.
“Our models also suggest that there could be significant additional drawdown in the vicinities of shallow well fields supplying public water systems of Woodstock and several other communities in southeastern McHenry County,” Meyer said.
The report also singles out Algonquin, Crystal Lake, Cary and Carpentersville as at-risk locations.
It continues that the drawing down of shallow aquifers would have an adverse environmental impact on the levels of creeks, streams, wetlands and other habitats. Natural groundwater discharge during the study period dropped by about 11.5 percent, with the greatest reductions being found at the outlet of Crystal Lake and Silver Creek in Woodstock.
A number of studies have warned that McHenry County’s explosive growth could one day outstrip nature’s way of supplying it with water, but concerns have moved out of the spotlight in recent years since the popping of the housing bubble and the sluggish economy that followed put the brakes on development.
A number of local governments have taken some measures to ensure adequate water supplies.
Many, like Crystal Lake and Lakewood, implement even-odd lawn watering during warm weather months, and ban it outright if drought conditions persist. More proactive governments include the village of Algonquin, which sits in the middle of an area deemed high-risk for future shortages in numerous studies. Water rates in the summer for Algonquin residents triple once customers exceed 18,000 gallons a month.