Improving Sediment Management At The Isleta Diversion Dam

The Isleta Diversion Dam (IDD) is located on the Rio Grande within the Pueblo of Isleta (POI) approximately 15 miles south of Albuquerque, NM. Since IDD began operating in the 1930s to deliver water to irrigators on both sides of the river, excessive sedimentation around the IDD and in the associated irrigation infrastructure has been problematic and costly to manage. The sedimentation also threatens the cultural and traditional needs of the POI. Impacts of excessive sedimentation include compromised canal capacities that impair reliable irrigation deliveries, disruptions to irrigation deliveries because of sedimentation sluicing operations, and decades of accumulation of unsightly dredged-sediment spoil on POI lands. Following a settlement between the POI, U.S. Bureau of Reclamation (Reclamation), Middle Rio Grande Conservancy District (MRGCD), and Bureau of Indian Affairs, the IDD Technical Team (TT) was established in 2016, in part, to address these sedimentation issues.

The IDD TT considered multiple approaches to improving sediment management around the IDD. Reclamation, MRGCD, and the POI’s technical consultant Tetra Tech agreed on hydrographic data collection and several different analyses to develop a cost effective, multi-pronged solution to reduce sedimentation and better manage impacts. Three rounds of physical sediment load and discharge measurements were completed during the above average 2019 spring runoff. A modified Einstein procedure was performed on an extensive gage record in Albuquerque and routed downstream with a one-dimensional mobile-bed model. A mobile-bed physical model that included a portion of the IDD and eastern canal headworks was designed and operated in the Hydraulics Laboratory at Reclamation’s Technical Service Center. A two-dimensional, mobile-bed model of the IDD was created to evaluate impacts of alternative gate operations. The upper portions of the main east side canal were modified to increase sediment storage capacity, reduce sediment diversions into lateral canals, and allow for more efficient removal of diverted sediment.

We will present these analyses and discuss how the collaborative approach taken by the TT resulted in a multi-pronged solution that is expected to exceed expectations for both reducing impacts of sedimentation and the expected cost to construct and operate.