Water Supply Planning

Water Supply Planning

The Chicago region obtains its drinking water from Lake Michigan, inland surface waters (Fox River and Kankakee River), and groundwater sources. The majority of water used in the region comes from Lake Michigan. Since Lake Michigan water is withdrawn, used, and then diverted out of the Great Lakes Basin, Illinois' access to lake water is governed by a U.S. Supreme Court Consent Decree that limits the amount of water that Illinois can withdraw. Lake Michigan water availability, managed by the Illinois Department of Natural Resources, Office of Water Resources, is allocated to the year 2030 with additional potential to serve a limited number of new communities that currently use groundwater.

Groundwater withdrawals from the deep-bedrock aquifer have generally been shown to exceed the recharge rate. Available studies have also revealed instances of withdrawals from the shallow-bedrock aquifers capturing subsurface water flow that would otherwise help feed our rivers and streams. Parts of the region could face adverse impacts of groundwater withdrawals by 2050 or sooner, including decreasing well yields, increasing pumping expenses, increases in salinity, and increased concentrations of radium, barium, and arsenic.

A combination of strategies by various stakeholders will be needed to ensure an adequate supply of water in northeastern Illinois. Water 2050 lays out a set of recommendations focused on water demand management, including water use conservation and efficiency measures. Appropriate water pricing is emphasized as a strategy that can influence demand and fund critical water system infrastructure maintenance and replacement.

In addition to demand management strategies, land use decisions also affect water resources in three major areas: aquifer recharge capacity, per capita water demand, and infrastructure investments. Aquifer recharge is affected by the location and extent of impervious surfaces (parking lots, rooftops, and streets) that prevent rainwater from recharging groundwater supplies. Housing density also plays a role; communities with low housing densities and corresponding large lawns have been shown to use more water. In addition, water lost through aging and leaky infrastructure results in significant waste of taxpayer dollars in addition to the valuable resource itself.  

As our region grows, it is critical that water resources are conserved and used efficiently. CMAP supports an integrated approach to water supply planning and uses Water 2050 and GO TO 2040 to guide programming. Learn more about these regional efforts: 

ON TO 2050 Regional Water Demand Forecast

CMAP, in partnership with Illinois-Indiana Sea Grant and the University of Illinois Extension, is updating the regional water demand forecast to the year 2050 for the seven counties of northeastern Illinois. Water 2050 and its corresponding water demand forecast, provide the region with key insights on demand and strategies for avoiding imbalances between water supply and demand. This project will build on the Water 2050 water demand forecast and provide one baseline forecast using CMAP’s ON TO 2050 socioeconomic forecast and recent water withdrawal trends. The updated forecast will provide results at the regional, county, and municipal scales, providing stakeholders with information at a more local level.

CMAP and IISG formed a technical advisory committee to provide critical information and feedback during the process. The ON TO 2050 Regional Water Demand Forecast will be complete by the end of June 2018, with data packages released in October 2018.

Water 2050: Northeastern Illinois Regional Water Supply / Demand Plan

CMAP facilitated and now leads implementation of Water 2050: Northeastern Illinois Regional Water Supply / Demand Plan in 2010. Water 2050 is a science-based plan that outlines how best to avoid an imbalance between water supply and demand in the Chicago region. 

Reducing Water Loss

CMAP is working with the IDNR Lake Michigan Water Allocation Program to improve understanding of water loss control practices and challenges faced by community water suppliers whose source of water is Lake Michigan.

Northwest Water Planning Alliance

CMAP is assisting the Northwest Water Planning Alliance, a coalition of over 70 communities and their county governments formed to collaboratively plan for shared groundwater resources.

Full Cost Water Pricing

CMAP, in partnership with Illinois-Indiana Sea Grant and the University of Illinois Extension, has developed a manual that explores full-cost water pricing as a tool for local decision makers interested in sustainably managing community water supply and infrastructure.  

Municipal Conservation and Efficiency Planning

Water conservation and efficiency planning and best practice implementation are two important means to ensure that the region has adequate water resources in the future. 


CMAP and partners have designed several resources to assist public water suppliers and municipalities interested in pursuing system efficiency and targeted conservation.