July 25: Endangered & Invasive Species, Lake Powell

An Ecosystem Degraded: Human Impacts on Riparian and Riverine Systems

 Mighty though the Colorado may be, it certainly isn’t exempt from modern-day ecological issues.  Human activities have offered a toe-hold for invasive species such as tamarisk, a fast-growing shrub thatthrives along the river’s banks, forces out native flora, contributes to salinity issues, and has been the focus of region-wide eradication programs for decades. In the river itself, ecologists are on the lookout for invasive Quagga and Zebra mussels, aquatic invaders that have taken other parts of the country by storm.  Meanwhile, changes in flow and temperature mean that warmwater fishes - including some on the endangered species list - are struggling. We floated the river with fish biologists and riparian ecologists to hear what’s being done to restore habitat and populations.

Lake Powell: Backup Bathtub or Evaporation Station?

 Lake Powell, the nation’s second-largest reservoir, was built in 1963 as a backup to Lake Mead, to store enough water to provide a consistent water supply to Lower Basin states in times of drought. The Colorado River Compact stipulates that Upper Basin states must provide 7.5 million acre feet of water annually to the Lower Basin states, and Powell is intended to help make that possible. The reservoir is also host to a 2-million-visitor-per-year recreation industry. Now, however, the cumulative impacts of dry winters, evaporation, and seepage mean that both Mead and Powell are far below capacity. That has led some to argue for opening up the Glen Canyon Dam and draining Lake Powell -- a prospect that would have wide-ranging implications.