Abstract: Session A 11:20 am (Back to Session A)
Restoring Overbank Flow Capacity in the Galisteo Creek, New Mexico
Ecotone Landscape Planning, LLC
Santa Fe, NM
Severely degraded in the last century, the Galisteo Creek, a mostly ephemeral stream across private properties, south of Santa Fe, NM, has been at the center of a series of ecological restoration initiatives in the Galisteo Basin between 2000 and the present. Restoration work aimed at improving aquatic habitat through geomorphic improvements and the conversion of riparian vegetation from Russian olive dominated to native willow-cottonwood vegetation, over a total length of 1.3 miles at two locations. Restoration activities included berm removal to improve flow access to old oxbows, remeandering of over-wound meanders (using post and rock vanes), construction of (beaver analog) post and wicker weirs and rock sills for grade control, and planting of willow whips and cottonwood poles. Many lessons were learned about the removal of invasive trees without the use of herbicides. The projects dealt with many challenges varying from reconciling different local, state and federal government regulations and grant requirements, garnering support from numerous private landowners, finding effective and lasting Russian olive removal strategies without using herbicides, negotiating cultural resource sites, working in sandy stream bottom conditions, and dodging extreme flow events during and immediately after project implementation. The work took in consideration the need to improve aquatic habitat conditions during low flows, periodic overbank flows, and exceptionally high flows. Due to urbanization and climate change, exceptionally high flows have appeared to become more frequent, and restoration work took the increased flow size diversity into consideration in the design of the work. Responses to extremely high flows included the identification of water release areas – such as old oxbows and high terrace flow paths –, and the reduction of floodplain roughness by removing invasive plants and planting willows. Removal of invasive trees was effectively accomplished without herbicide application by manually cutting stems and extracting the roots with the use of an excavator. Branches were chipped and rootwads were hauled off or used as foundational fill material. Geomorphic modifications that stimulated overbank flows aimed to (sub-)irrigate the floodplain in ways that would drown invasive plants and stimulate native vegetation. Monitoring results indicate that project outcomes have been very encouraging.