Lessons Learned from Minute 319 Implementation in the Colorado River Delta
Karen J. Schlatter*1, Eloise Kendy2, Karl Flessa3, and Jennifer Pitt 4
1Sonoran Institute, 100 N. Stone Ave., Ste. 400, Tucson AZ 85701; 520-290-0828; kschlatter@sonoraninstitute.org;
2The Nature Conservancy, 415 Monroe Ave., Helena MT 59601; 406-495-9910; ekendy@tnc.org
3University of Arizona, Tucson AZ 85721; 520-621-7336; kflessa@email.arizona.edu
4National Audubon Society, Boulder CO 80302; 720-841-5366; jpitt@audubon.org
Minute 319, an addendum to the U.S.-Mexico 1944 water treaty piloted from 2012-2017, provided new guidelines for Colorado River binational water management, including provisions to dedicate environmental flows to the Colorado River Delta in Mexico. The following key lessons learned relate to restoration, water deliveries, monitoring, and benefits of Minute 319.
- Tradeoffs of “pulse flow” water delivery versus targeted water deliveries to restoration sites:
- Much of the water from the 2014 pulse flow delivery to the Delta infiltrated into a dry reach of river, where there were little benefits to native habitat. Targeted flow deliveries to restoration sites via agricultural irrigation canals can ensure effective use of water for habitat restoration but lack other benefits of a pulse flow.
- Active versus passive restoration:
- Passive restoration of native habitat was largely unsuccessful due to a lack of bare ground created by river bank scour from the pulse flow. Areas with non-native vegetation mechanically removed prior to the pulse flow release had successful germination and establishment of native riparian species.
- Social benefits:
- The community response to the 2014 pulse flow release was unexpected, hugely positive, and generated support for future environmental flows and restoration.
- Data management and sharing:
- The monitoring effort of Minute 319 lacked a data management framework and dedicated funding and personnel, which resulted in difficulties in timely data sharing, standardization across organizations, and interpretation of results.
- Planning for long-term success:
- Restoration and water delivery planning should take into account 1) changing background conditions due to drought and water use changes, 2) large-scale and long-term management and funding needs.
With the successor agreement Minute 323 (signed September 2017) already underway, government agencies, restoration practitioners, water managers, scientists, and local community members are drawing on Minute 319 lessons learned to inform implementation of the new Minute.