A number of different systems have been used to estimate boater use over the 1990-2001 period, making it difficult to trace the source of discrepancies in the final estimates. For example, the boater passes have changed over the years. From 1990-92, boaters would simply check off the river segments they were intending to boat. After 1992, they were asked for their launch and take-out locations, and after 1997, the check boxes were taken off the boater pass form. There have also been differences in how incomplete or inaccurate boater passes have been handled. Finally, there are differences in the computer programs that transform the boater pass data into segment and overall use estimates. Without agreement and confidence in the boater use estimates, management decisions become difficult. The interested parties were unable to come to an agreement about the reasons for the boater use level discrepancies, and asked the Institute for Natural Resources (INR) to research the issue.