Relationship Between U.S.-Mexico Border Operations and Turbidity in the Headwaters of the Rio Yaqui
USFWS, AZGFD, Cuenca los Ojos Foundation
September 2011 to December 2013
The Real Id Act of 2005 (H.R. 418-109th Congress, 2005) gave the Secretary of Homeland Security authority to waive all laws which would inhibit completion of the border fence and roads, including environmental laws, thus increasing the potential for ecological degradation along the border. Negative impacts of border operations have been documented in many terrestrial species, yet little is known about the impacts of operations on aquatic ecosystems. San Bernardino National Wildlife Refuge (SBNWR) is located just north of the United States (US)- Mexico border. Construction of bridges and roads on or near SBNWR, and activities conducted by the US Border Patrol, such as dragging roads to check for footprints and patrolling dirt roads in and around SBNWR, have prompted concern about increased sedimentation of the Rio Yaqui. Increased sedimentation could elevate total suspended sediment (TSS) and turbidity in the Rio Yaqui thus causing changes in diet and survival of fishes inhabiting the system. To determine the impact of border patrol activities on TSS and turbidity in Black Draw, 32 Nalgene stormwater samplers, which collect a single 1L first flush grab samples, were installed along Black Draw and Hay Hollow Wash, tributaries to Rio Yaqui, upstream and downstream of potential sources sediment. Samples are analyzed for TSS concentration and turbidity. Levels of TSS and turbidity will be compared to ambient levels of TSS and turbidity in the river. TSS and turbidity analyses are being completed as storm events occur.