1. United States
2. Ill.
3. Letter

I am writing to urge you to support legislation that regulates water usage by data centers in Illinois to protect Lake Michigan and the Great Lakes, which provide drinking water to over 40 million people in our region. A recent report from the Alliance for the Great Lakes reveals that AI-powered data centers consume more than 365 million gallons of water annually, equivalent to the water usage of 12,000 Americans. With Illinois already hosting more than 187 operating data centers according to a 2024 Landgate report, and global demand for data center capacity expected to more than triple by 2030, we face a serious threat to our finite freshwater resources. Over the next five years, U.S. data centers are projected to use as much as 150 billion gallons of water, equivalent to the consumption of approximately 4.6 million American households. The Great Lakes contain approximately 20 percent of the planet's freshwater supply, but only about 1 percent of their water volume is replenished annually through rain, snow, and groundwater inflow. These resources were created from glaciers that melted thousands of years ago and cannot be replaced. The primary cooling method used by data centers, evaporative cooling, consumes water by pushing it through membranes to cool server rooms, with more than half evaporating during the process. Helena Volzer, senior source water policy manager at the Alliance for the Great Lakes, emphasizes that a critical problem is the complete lack of transparency around data center water usage. When connected to municipal water supplies, there are no tracking or reporting requirements for individual facilities, and non-disclosure agreements further obscure consumption patterns. I urge you to champion legislation requiring public disclosure of data center water and energy usage, clear assessment of environmental impact during site acquisition, and community information sharing about new projects. We should also explore innovative approaches like leveraging Chicago's Tunnel and Reservoir Plan system, which has a capacity of nearly 12 billion gallons, to provide water for data centers strategically positioned near wastewater treatment plants. Without proper planning and regulatory action now, Lake Michigan and the broader Great Lakes ecosystem face significant risks as the AI industry expands. Our drinking water supply depends on your leadership.