Acknowledgments

The authors wish to thank cooperating agencies and their staff including Maggie Skenderian and Frank Wildensee (city of Portland), Carrie Pak (formerly of city of Gresham), Lynne Kennedy and Torrey Lindbo (city of Gresham), the late George MacGregor (city of Milwaukie), Ela Whelan (formerly of Clackamas County), Andrew Swanson and John Nagy (Clackamas County’s Water Environment Services), and Kim Peoples (Multnomah County). Special thanks go to Mark Liebe (city of Portland) for inspiration and excellent insight regarding groundwater flow in the basin, and to Ivy Francis (formerly of the city of Portland) for the original request for assistance in 1997. Land owners throughout the basin provided access to properties for data collection during the study. Tiffany Jacklin and Melanie North (USGS) provided data base support. USGS personnel, beginning in the early 1940s provided the basic (and essential) data used in the interpretations developed in this report.