YOUR BEST PRACTICE
A new siphon alignment has been designed to replace this essential infrastructure at an estimated cost of $15 million. Central recently sought funding assistance of $8.9 million from the state’s Water Sustainability Fund, a source of financial support to help local project sponsors achieve goals set out in state statute. The Nebraska Natural Resources Commission (NRC) oversees the fund, including application review, scoring and ranking, and awarding funding to successful applicants. The Department of Natural Resources administers the fund by initially reviewing applications and forwarding those that meet minimum statutory requirements to the NRC.
Current irrigation releases would continue through the existing system during construction of the new canal/siphon project. The new siphon system would be approximately 5,400 feet long and would consist of high-density polyethylene (HDPE) pipe and approximately 5,300 feet of open canal sections protected by a combination of riprap and synthetic lining. Installation of the new siphon would secure uninterrupted long-term delivery of water in the E-65 system and ensure that irrigation, recharge, recreation and wildlife benefits are sustained into the future. Maximum flows through the siphon would be approximately 450 cubic feet per second.
A failure of the existing siphon(s) would result in the loss of irrigation deliveries
MORE REPAIR PROJECTS PLANNED
The Central Nebraska Public Power and Irrigation District is also currently preparing for a project to repair the Elwood Reservoir dam. Areas of seepage were discovered after the reservoir was operated at high water levels for longer periods of time to support requests from the Nebraska Department of Natural Resources, Tri-Basin Natural Resources District and the Platte River Recovery Implementation Program to use extra reservoir storage for groundwater recharge. The project is estimated to $4 million and will be funded by Central, which is committed to ensuring sustainable water resources benefits to the area.
to the area, with significant coinciding economic impacts. In addition to the regional economic effect of lost agricultural income, multiple secondary benefits also would be lost, such as groundwater recharge and recreation. The inability to convey water through the siphons would ultimately result in a dry Elwood Reservoir. In turn, the absence of water in the reservoir would result in the loss of water-based recreation, the fishery, and important groundwater recharge to both the Platte and Republican Basins.
The groundwater recharge provided by Elwood Reservoir and the E-65 Canal benefits both river basins — in addition to area groundwater users — by enabling the state and other entities with water management responsibilities in the region to meet state and federal obligations. This includes the Republican River Interstate Compact and efforts related to Endangered Species Act compliance through the Platte River Recovery Implementation Program.
The new siphon route for E-65 would eliminate the need for costly pumping and is approximately four miles shorter than the existing route.
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The groundwater recharge provided to the Republican Basin is counted as an “Imported Water Supply Credit” by the interstate (Colorado, Kansas and Nebraska) compact. It is estimated that the E-65 system provides about 10,000 acre-feet
annually to the Republican Basin, which would not occur without functioning siphons. In addition, other management actions would be required to replace lost recharge such as utilizing water from the Nebraska Cooperative Republican Platte Enhancement project, which pumps groundwater to offset streamflow depletions in the Republican and Platte basins, or shutting down or allocating irrigation usage.
LEARNING FROM EXPERIENCE
Central officials cite a tunnel collapse that occurred along the Gering-Fort Laramie Canal in Wyoming in July 2019 as a lesson on the consequences of not addressing aging critical infrastructure. According to a report prepared by Nebraska Extension, Wyoming Extension and the University of Wyoming Department of Agricultural and Applied Economics, the tunnel collapse interrupted irrigation deliveries to 107,000 acres in eastern Wyoming and western Nebraska and resulted in total economic losses of $89 million.
The siphon project illustrates the critical nature of irrigation canal works in an agricultural economy dependent upon irrigation. A proactive approach to replace the siphons will preserve the regional economic vitality supported by the 42,000 irrigated acres within the E-65 Canal area as well as the significant benefits of groundwater recharge and water-based recreation associated with the system.
Scott Dicke is the irrigation and water Public Power and Irrigation District.
Winter 2022 | Irrigation TODAY 27
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