On January 24, 2011, the Illinois Department of Natural Resources (IDNR) Office of Water Resources approved allowing ten Lake County communities to access water from Lake Michigan.  This follows a decades-long regional trend -- whenever a groundwater-dependent community in the greater Chicago region has experienced water supply or water quality problems, they have been granted approval to switch to Lake Michigan water.  Thanks to the bounty of our Great Lake, a U.S. Supreme Court Consent Decree that permits these diversions, and effective IDNR management, over three-quarters of the region’s population quenches its thirst with Lake Michigan water in a manner that is both legal and unique within the Great Lakes Basin.

How long will this trend continue?  Two years ago, IDNR determined that an increase of 50 to 75 MGD (millions of gallons per day) in domestic water supply allocation to new areas could be accommodated by 2030 without major policy changes in Illinois diversion management.  IDNR’s determination followed a recent allocation review and new demand forecasts for all domestic permittees.  This 50 to 75 MGD increase is roughly five percent of the total 2030 forecast of allocations to existing communities (1209.8 MGD). If these ten Lake County communities start withdrawing water from Lake Michigan in 2015, their collective allocation will grow to 15 MGD in 2030 (close to one-third of the remaining allowable increase).  Barring any additional new requests for lake water between now and then (an unlikely scenario), the water remaining for other new allocations will be just 4 percent of water allocated for domestic pumpage in 2030.

From a “glass half full” perspective, things look good.  However, several conclusions from CMAP’s recent Water 2050 plan, which analyzes and forecasts regional water demand and considers impacts on groundwater supplies out to the midcentury, offer some cause for alarm. Water 2050, published last year, is the culmination of a three-year planning process that was funded by IDNR as the lead state agency charged with defining a comprehensive program for state and regional water supply planning and management.  Water 2050 also involved diverse stakeholder input and guidance from the Regional Water Supply Planning Group.  Based on current groundwater use, modeling (from the Illinois State Water Survey) and regional water demand scenarios, the plan concludes that without appropriate interventions, the groundwater-dependent subregion is in danger of compromising the integrity of their water sources.

Water 2050 estimates that demand for groundwater will increase between 84 to 135 percent by 2050 with a “business-as-usual approach” to local water use.  That translates into 211 to 337 MGD of new groundwater withdrawals from a system of aquifers that are not being used sustainably at today’s withdrawal rates.  While not every groundwater-dependent community will have Lake Michigan water access as a viable option, many could.  For example, who would have ever thought that lake water would flow into Kendall County as it does today in Plainfield?  Likewise, if the Village of Fox Lake taps into lake water as has just been approved, the myth that McHenry County will never use Lake Michigan will be busted too.  But to ensure that today’s groundwater-dependent communities continue to have Lake Michigan water as an alternative, management of the Illinois diversion, specifically the domestic pumpage component, could become more proactive and aggressive with efficiency gains and waste reduction.  For example, Illinois could adopt high-efficiency toilets (HETs) as the new standard required under its water conservation conditions established for an allocation permit.  HETs are becoming standard components in water conservation programs around the country.  Illinois could also strengthen its ordinance-adoption requirement that addresses summertime lawn sprinkling.  Per the CMAP Model Water Use Conservation Ordinance, residential landscape irrigation should be allowed only two days per week.  Currently, three to four days per week (i.e., odd-even days) is commonplace.   

To be sure, the Illinois diversion is a complex system of water-use management and accounting, with most diversion components variable from year-to-year (see graphic below).

For example, weather (i.e., wet vs. dry years) and resultant stormwater runoff affect diversion accounting and can impact Illinois’ compliance with the terms set out in the Consent Decree.  Leakage, another diversion component, will now be reduced thanks to the refurbished Chicago Harbor Lock.  That the region’s relatively small buffer of available Lake Michigan water is about to get smaller, however, should only add to a growing sense of urgency for IDNR to do more now.  With over 240 recommendations,Water 2050 makes the science-based case for action and points the way forward in a regionally approved direction.  Many of the plan’s recommendations are made for IDNR, including some that are specific to the Lake Michigan Management Section.  For example, the plan recommends that the IDNR Office of Water Resources’ Lake Michigan Management System eliminate the Maximum Unavoidable Loss allowance granted to permittees without raising the acceptable loss threshold (currently at 8 percent).  All of the recommendations are made with any eye toward maintaining regional prosperity -- a prosperity that depends on adequate supplies of water for all users including millions more new people expected to call the Chicago region home by midcentury.