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Speakers): Patrick B. Shafroth, Distinguished Volunteer, Fort Collins Science Center; Pamela L. Nagler, physical scientist, Southwestern Center for Biological Sciences; Eduardo Gonzalez-Sargas, Research Scientist, Colorado State University
Date: November 18 at 2:00 p.m. Eastern Time
Summary: A treaty signed by the United States and Mexico in 1944 and various subsequent amendments (“minutes”) are the basis of binational agreements between the two countries, including water management of the Colorado River. One aspect of these agreements in the Colorado River Delta (in Mexico, downstream from the United States) involves the allocation and delivery of water from the Colorado River to support efforts to restore riverine ecosystems. In his A Sand County Almanac (1949), Aldo Leopold described the thriving ecosystems of the Colorado River delta. However, by the 1960s the combined effects of flow depletion and land conversion had greatly reduced the quantity and quality of these systems and the river rarely flowed to its terminus in the Gulf of California. While some of the USGS’s involvement in the delta began in 1998, significant efforts at several science centers began in 2014 and continue to the present in the context of Minutes 319 and 323. In the case of these two minutes, a portion of the Colorado River has been allocated to support efforts to restore native riparian forests, which provide critical habitat for migratory birds. Minute 319 largely focused on a single high or “pulsing” flow in 2014 and lower flows from 2015 to 2017. As part of minute 323, which began in 2018 (and is expected to end in 2026) , water deliveries are primarily used to irrigate managed restoration areas. USGS scientists have led and lead multiple efforts and support others related to these restoration activities. Under 319 minutes, USGS scientists conducted a series of studies related to “pulsating flow,” including surface and groundwater hydrology, riparian vegetation dynamics, large-scale changes in vegetation “greenness” and actual evapotranspiration (ETa), and sediment transport and transport. geomorphological change. The results of these efforts were published in a special issue of the journal, Ecological Engineering (2017) – USGS had five co-authors on eight of the issue’s 17 papers and served as co-editors. As part of 323 min, major research activities included the continued processing and analysis of remote sensing data to assess the large-scale dynamics of vegetation and ETa in the riparian corridor, and the development of several publications related to avian use of these delta habitats. Both of these outbreaks are largely conducted in the context of evaluating the effects of restoration efforts. Two key USGS activities over the past several years related to data provision have been to 1) provide actionable science to end users through the development of a searchable, remotely sensed database of the greenery of the vegetation and ETa, and 2) lead the development of a database system for data sharing and archiving within the Minute 323 Science and Monitoring community. This community includes a myriad of scientists and government, NGO and academic stakeholders on both sides of the border. Another important role of the USGS has been to provide technical assistance on a range of topics to our partners. During the remaining four years of Minute 323, planned activities include the continuation of ongoing efforts with regard to the evaluation of the results of restoration actions on variables such as vegetation, hydrological processes (for example, ETa), and avian ecology. New efforts include helping restoration practitioners improve understanding of the dynamics and influences of target restoration habitats and the importance of connectivity between habitat patches; help develop a system to provide early warning of water stress that can negatively affect vegetation in restoration sites; and expanding surface water and groundwater modeling efforts.