Monroe Drop Project - Complete Application Received
February 9, 2023: The Low Impact Hydropower Institute has received a complete application for Low Impact Certification of the Monroe Drop Hydroelectric Project. LIHI is seeking public comment on this application. Specifically, we are interested in knowing whether you think the Project meets the LIHI Low Impact Certification Criteria, as revised in the 2nd Edition Handbook. Please review the program and criteria in LIHI’s revised Handbook and then review the Project’s application materials below.
Comments that are directly tied to specific LIHI criteria (flows, water quality, fish passage, etc.) will be most helpful, but all comments will be considered. Comments may be submitted to the Institute by e-mail at comments@lowimpacthydro.org with “Monroe Drop Project Comments” in the subject line, or by mail addressed to the Low Impact Hydropower Institute, 1167 Massachusetts Avenue, Arlington, MA 02476. Comments must be received on or before 5 pm Eastern time on April 10, 2023 to be considered. All comments will be posted to the web site and the applicant will have an opportunity to respond. Any response will also be posted.
| Project Name | Monroe Drop |
| LIHI Certificate No. |
N/A |
| LIHI Certificate Term |
N/A |
| Owner | Natel Energy |
| State | Oregon |
| Location | North Unit Irrigation District Main Canal |
| Installed Capacity | 0.3 MW |
| Average Annual Generation | 1,078 MWh |
| Facility Type | Run of canal (operates only if there is sufficient flow in the canal) |
| FERC No. | P-14430. Conduit exemption issued August 1, 2014 |
The Monroe Drop Project is located within the Deschutes River Basin on the North Unit Irrigation District Main Canal (NUMC), near Culver, Oregon. The project boundary encompasses 2.1 acres within the Crooked Creek National Grasslands administered by the US Forest Service (USFS) and within a US Bureau of Reclamation (USBR) held easement for the NUMC. Construction of the North Unit Irrigation project began in 1938 and was completed in 1949. The NUMC and Monroe Drop are facilities operated by the North Unit Irrigation District (NUID) with a primary purpose to deliver irrigation water.
Principal features of the irrigation project include Wickiup Dam and Reservoir, Crane Prairie Dam and Reservoir, Haystack Dam and Reservoir, North Unit Main Canal and lateral system, and the Crooked River Pumping Plant. Releases from Wickiup Reservoir are diverted from the river at the North Canal Dam in Bend, OR which was built by local interests before USBR construction work began. Water is carried to about 50,000 acres of irrigated lands by the North Unit Main Canal and distributed through a system of laterals. Water stored in Crane Prairie Reservoir (upstream of Wickiup Reservoir) is also diverted by the North Canal Dam into delivery and distribution systems to more than 47,000 acres. It was built and is operated by Central Oregon Irrigation District and Crook County Improvement District No. 1.
The North Unit Main Canal is one of three irrigation canals that originate at the North Canal Diversion Dam at RM 164.8 on the Deschutes River. The Crooked River Pumping Plant is located where the North Unit Main Canal crosses the Crooked River at about RM 27.6. The canal diverts water from the Deschutes and Crooked rivers approximately 37 miles, and 11 miles south (upstream) of the hydro project, respectively through a series of canals and drop structures to irrigate the surrounding farm land.
The Main Canal’s Monroe Drop structure is a 35-foot-long, 15-foot-high concrete open irrigation drop with winged transition sections upstream and downstream. Water falls between 13.5 feet to 16.5 feet at this structure, depending on flow. The Monroe Drop also contains an automated gate that controls the normal flow of irrigation water through the Main Canal.
Monroe Hydro was issued a FERC conduit exemption on August 1, 2014 and was constructed in 2015 with one Natel SLH100 turbine, a powerhouse, intake channel and a draft tube in the lower canal. An Obermeyer gate in the main canal spillway controls the head at the project site and is fully inflated during the entire operating season. The Obermeyer gate is lowered during the canal weed flushing periods to allow for all canal debris to pass the project and not cause blockage in the facilities. The Obermeyer gate is not part of the FERC exemption as it is part of the canal operating system. The SLH turbine was later replaced with a Natel Restoration Hydro Turbine (RHT) under an exemption amendment issued by FERC on January 20, 2020. The RHT is a compact hydroelectric turbine that couples high performance with safe through-turbine fish passage. Uniquely thick fish-safe blades optimized for low head applications eliminate the need for fine fish screens, reducing costs while also increasing plant efficiency.
The turbine replacement required replacing the top section of the rectangular draft tube with a cylindrical draft tube. This modification required a modification to the wingwall notch to accommodate the slightly enlarged draft tube. The lower section of the draft tube which is supported by a foundation in the canal was not modified. The existing intake (48-foot-long, 7-foot-diameter pipe) and powerhouse structures were not modified and the enlargement of the already existing wingwall notch to accommodate the draft tube structure was the only necessary change to canal civil structures. The project discharges water back to the Main Canal through a 25-foot-long rectangular section draft tube of varying dimensions. The project also includes a 2,200-foot-long power line buried in conduit under the canal service road that interconnects with a 12.5-kV distribution line owned and operated by PacifiCorp.
The nameplate of the project is 300 kW and it generates approximately 1,078 MWh annually during the irrigation season. The design head range averages 4.7 meters with a flow of 323 cfs through the plant which fluctuates based on the available flow. The project operates as a run-of-river project and runs seasonally in coordination with the normal irrigation season, April-October. The project does not change the timing or location of water delivered to irrigation users and after irrigation season the canal is drained.