Although the aims of environmental legislation are well known, measuring the effects of regulation is often a difficult task. Inadequate data for baseline conditions and the recovery period can hamper efforts to quantify the effects of a regulation. In a rare exceptional case, Dr. Daniel Gibson-Reinemer and his colleagues describe in BioScience the successful recovery of the Illinois Waterway following the implementation of the 1972 Clean Water Act. Using a robust, multi-decadal data set, the authors demonstrate a tight linkage between water quality and the rebound of numerous fish populations. Dr. Gibson-Reinemer joins us in this episode of BioScience Talks to discuss the article's findings and to explain their possible application in future recovery efforts.