Streambank stabilization methods for use following extensive chemical spraying of saltcedar along the Pecos River, N.M. to ensure efficient water delivery.
What restoration methods can best stabilize the saltcedar lined streambanks of the Pecos River following extensive chemical spraying of the saltcedar? Saltcedar was planted as a soil stabilization species in the 1920s. Thousands of acres of saltcedar along the Pecos River have been sprayed or will be sprayed with the herbicide, Arsenal, to promote water salvage. To get the best kill, saltcedar must sit for two years following spraying to allow the chemical to be fully taken into the tree roots. Concern is now being voiced that sprayed, dying trees may start to fall into the river, impeding water flow, and that streambanks may become unstable and slump into the river, adding to its sediment load. This research proposes to explore and test the best methods for stabilizing the streambanks of the Pecos River using desirable vegetation and other appropriate materials.Changes in amount of vegetative groundcover and changes in streambank erosion will be quantified and monitored 4 times/year.
Need and Benefit
Large-scale spraying of saltcedar along the Pecos River began in New Mexico in 2002 and in Texas in 1999 so the issue of instability of streambanks along the Pecos River is a relatively new one. Treated trees are falling into the Pecos along some river segments in Texas, raising the concern that this may become widespread along other portions of the river. As coarse saltcedar roots disintegrate with time, they may allow greater bank erosion resulting in greater sediment loading in the river.
Reclamation does not have a stream-bank stability program in existence which stresses using native shrubs and grasses whose denser, finer root structures are better suited to holding soils in place. Reclamation has done a limited amount of work in the past identifying grass species suitable for lining canals.
This project will help Reclamation prepare for saltcedar management activities resulting from recently passed Domenici Bill.