Monroe Drop Hydro Project

Culver, Oregon
Project Stats
Turbine Supply:
Natel Energy
Project Developer:
Natel Energy
300 kW
5 m (16 ft)
Number of RHT Units:
RHT Unit Diameter:
1.9 m (6 ft)
RHT Unit Type:
PIT D190
Commission Date:
September 2020

The Monroe Drop Hydro Project makes use of an existing irrigation canal to generate 300 kW of reliable, renewable energy annually to serve Central Oregon communities via the local grid.

The irrigation canal and the Monroe Drop structure are irrigation facilities operated by the North Unit Irrigation District (NUID) with a primary purpose to deliver irrigation water to nearly 50,000 acres of farmland in Jefferson County. Water for the irrigation project comes from both the Deschutes and Crooked Rivers.

The Main Canal’s Monroe Drop structure consists of a 35­-foot-­long, 15­-foot-­high concrete open irrigation drop with concrete winged transition sections upstream and downstream. Water falls between 13.5 feet to 16.5 feet at this structure, depending on the flow. The drop structure contains an automated gate that controls the normal flow of irrigation water through the Main Canal.

The hydro facility was constructed in 2015 and consists of a 12 ft x 61.5 ft concrete intake channel, a 25 ft x 44 ft powerhouse containing a single generating unit, and an approximately 50 ft rectangular-section draft tube. A 2,200­-foot-­long power line buried in conduit under the canal service road connects to a 12.5-kV distribution line owned and operated by PacifiCorp. Natel replaced the original 250-kW SLH turbine with a 300 kW Natel D190 Restoration Hydro Turbine (RHT) in 2020. The project operates in a “run-of-canal” mode generating electricity from available water flowing through the drop structure during the irrigation season only (April through October). During emergency powerhouse outages, flow that would normally pass through the powerhouse remains in the canal. The Obermeyer gate automatically adjusts to maintain constant elevation upstream of the drop structure and to maintain flow downstream of it, and typically remains fully inflated during the irrigation season. Project operations do not impact the timing or location of water delivered to irrigation users.

The intake at the Main Canal diversion dam on the Deschutes River, located 37 miles upstream from Monroe Drop, is equipped with a trash rack and fish screening, but it does not meet current state standards. Oregon Department of Fish and Wildlife (ODFW) reports that resident fish including redband trout, brown trout, and mountain whitefish have been observed stranded in the dewatered canal downstream of the Main Canal intake; and kokanee salmon have been observed in Haystack Reservoir which is located 6 miles downstream in the canal from the project. During the irrigation season, any fish moving downstream from the canal intake could therefore continue moving downstream through the project, as Natel's RHT design has been shown to provide safe downstream fish passage in laboratory and field testing.

Natel has conducted two field tests at the Monroe Drop project itself, studying the passage of adult rainbow trout of different sizes through the 1.9-meter-diameter turbine. More details about the 2020 test are available here, and about the 2022 test are available here.

The Monroe Drop is certified as a Low Impact Hydropower project by the Low Impact Hydropower Institute (an independent non-profit organization) to have environmental impacts in key areas below levels the Institute considers as the maximum acceptable for hydropower facilities. For more information about the certification, please visit