PARENT SESSION
Oral Session #37: River and Riparian Restoration II.
Presiding: J. Berg
Tuesday, August 6. 1:00 PM to 4:00 PM. Mohave Meeting Room, TCC.
Restoration of natural processes to benefit riparian habitat on the Bill Williams River, Arizona.
WERNER, WILLIAM*,1, 1 Arizona Game and Fish Department, Phoenix, Arizona
ABSTRACT- Beginning in 1990 an interagency effort, lead by Arizona Game and Fish Department, was begun to address competing water management concerns for management of Alamo Lake and the Bill Williams River downstream. During the process optimal and acceptable prescriptions for operation of Alamo Dam were developed for a number of interest areas, including riparian habitat, particularly Populus fremontii and Salix goodingi. These recommendations and others were screened through dam operation constraints. Alternatives were then developed which included common factors. Riparian habitat stream flow requirement factors included seasonal base flows for downstream riparian habitat needs, including releases needed to overcome the effect of Planet Ranch pumping, and releases to mimic natural flood flow events in pattern if not in magnitude. Other common factors included rate of change of reservoir elevation limitations for lake fishery spawn, rate of change of reservoir releases limited for public safety, reservoir drawdown at 5-year intervals for inspection and maintenance. Performance of alternatives was modeled using the HEC-5 computer model using daily hydrologic data for the period 1928-1993. A consensus recommendation to the Corps of Engineers was developed based on review of alternative performance relative to agency goals. The Corps of Engineers then conducted formal reconnaissance and feasibility studies and an environmental impact statement on alternatives, including the consensus recommendation. Fortuitously, during the process heavy rainfall necessitated large reservoir releases, providing an opportunity to monitor effects of the recommended schedule and initiation of adaptive management. Cottonwood and willow trees have flourished in areas where decadent stands had been dying out.
KEY WORDS: Populus fremontii, Salix goodingi, dam operation, water managment