History of the DuPage Water Commission (page 2) In March of 1984, the Commission signed a 40-year agreement to buy water from the City of Chicago for redistribution in DuPage County. The Water Commission Act of 1985 gave the Commission the authority to finance, design, construct and operate a Lake Michigan-to-DuPage County water supply system. In 1986, the Commission entered into "wholesale" Water Purchase Agreements with 23 DuPage County municipalities, and began the construction of the second largest water supply system in the State of Illinois. The Commission finally went into full operation on May 1, 1992.