The report is Vol. 4, of a series of 7 reports summarizing Illinois EPA's 1987 Volunteer Lake Monitoring Program (VLMP). It provides a program overview, a summary of 1987 VLMP lakes in West-Central Illinois, including a discussion of lake characteristics, volunteer participation, and a ranking of lakes on a regional basis. West-Central Illinois results are compared to statewide statistics. Lake assessment information from the Illinois Water Quality Report 1986-1987 for West-Central VLMP lakes is provided and briefly discussed. Lake/watershed management strategies are described. Thirty-five volunteers recorded total depth, Secchi disc transparency, and field observations for 20 lakes in West-Central Illinois between May and October, 1987.