The report is Vol. V of a series of 7 reports summarizing Illinois EPA's 1986 Volunteer Lake Monitoring Program. It provides a program overview, summarizes results for 25 lakes in East-Central Illinois, and discusses lake/watershed management strategies. It also contains individual analyses and recommendations for lakes monitored during 9 or more sampling periods, and data for lakes monitored 4-8 sampling periods. Thirty-eight volunteers recorded total depth, Secchi disc transparency, and field observations for 25 reservoirs in East-Central Illinois between May and October, 1986. Average transparencies ranged from 10.5-97.6 inches. Twenty percent of the lakes exhibited average transparencies greater than 4 feet, 44% between 2 and 4 feet, and 36% less than 2 feet. One lake was classified as mesotrophic, and the remainder, eutrophic, based on average Secchi disc transparency.