Let’s address the elephant in the room, first. There are voices within Idaho suggesting that hydroelectric generating plants on irrigation canal systems are focused more on generating power (and selling it) than they are on serving the irrigation needs of Idaho agriculture.
“Some have accused us of spilling water back to the river [instead of using it for irrigation] in an attempt to generate more electricity,” says Alan Hansten, Northside Canal Company (NSCC) manager. “Not true. We don’t want to spill; we want to take care of our irrigators. We can take Milner Dam to zero-spill, and we often do … as long as the Swan Falls minimum flow is adequate, as required by law. Water flow at the end of our ditches that spills back to the Snake River helps meet minimum flow requirements at the Swan Falls dam. There’s a misconception that we’re making money on electricity and we’re not prioritizing water use to irrigate crops. That’s not accurate. Hydropower is a byproduct of irrigation. Irrigation for agriculture drives the energy, not the other way around.”
Why canals?
In bygone eras, power was generated through waterwheels. To increase power generation, the only option was to increase the size of the wheel, but construction costs and stream dimensions severely limited that option. Later advancements in technology led to designs, such as blade turbines, that could generate more electricity within low-flow water applications. Manmade canal systems have an inherent advantage over natural stream flows as they are constructed with uniformity and consistent slope. They are also less susceptible to sediment deposition or erosion than their natural counterparts.
How does a canal company afford these?
Today, NSCC, centered in Jerome County, has five hydroelectric plants on its canal system, from Milner Dam to the Jerome area. The first four plants were installed by private investors, Sithe Energies and Ida-West Energy, beginning in 1989, whereby a 30-year contract would pay a small royalty to the canal company to help offset canal maintenance costs. At the end of the contract, the investor would sell the hydroelectric plant to NSCC for a nominal fee. Beneficial to both parties and ahead of schedule, NSCC later bought out the last remaining years of the contract in 2018 in two of the plants. They then reinvested in the systems with updates and mechanical upgrades, which should make them last at least another 30 years.
The “Head of the U” hydroelectric plant came online in 2015 and was funded through canal company efforts by obtaining a USDA grant and loans.
Design
The four power plants near Hazelton on the NSCC system all have a similar design using Kaplan turbines – a propeller-type turbine with adjustable blades. The most recent installation at Head of the U uses a simpler structural design with a siphon-type turbine.
“It functions a lot like an old siphon tube on a ditch bank,” Hansten says. Air is evacuated from the tube and water begins to flow and power is generated. “Twenty feet of drop is generally considered the lower limit for a hydro project to be financially viable, and the lava-ridden north side of the Snake River provides some opportunities to capitalize on that requirement. At the Head of the U plant, a 10-foot drop occurred naturally in the canal, and with a bit of blasting on the downstream side and a bit of building up the bank on the upstream side, the required 20-foot drop was achieved.”
Operation and maintenance
NSCC employs two full-time hydroelectric power-plant operators and one part-time operator who also doubles as a ditch rider. The plants run 24/7, April through October, during the irrigation season, which coincides with peak electricity demand from all power customers. Together, the five hydroelectric plants produce 100,000 megawatt hours (MWh) – enough to support about 9,000 homes per year.
Maintenance is performed during the offseason to the runners (or propeller blades), addressing any cavitation in the system or replacing worn parts, like seals on the shaft that connect to the generator, which becomes worn from soil and silt.
The payoff
Energy produced from the NSCC hydroelectric plants is sold to Idaho Power. The Public Utility Regulatory Policies Act (PURPA) was passed in 1978 following the energy crisis of the 1970s. It encouraged electrical generation and promoted competition and energy conservation. It is implemented by the Federal Energy Regulatory Commission and the individual states. It imposes mandatory purchase obligations on electric utilities, such as Idaho Power, for small power production facilities.
Hydropower rates paid to producers are generally higher than solar or wind, mostly because it’s less variable in its production, Hansten says. Solar and wind are dependent on the sun shining or the wind blowing, while hydro plants run 24/7 regardless of weather.
“A hydroelectric plant is a revenue stream to help combat the rising costs of maintaining a canal system,” Hansten says. He says the current water assessment fee for NSCC irrigators covers about half of the annual revenue needed to maintain and operate the canal system. He credits the company’s ability to implement new projects and improve the canal system to the electrical plants.
Ongoing issues
There are ongoing issues for all small hydroelectric facilities with the Idaho State Tax Commission regarding operating property tax valuation. This issue is still working its way through the court system, Hansten says. While the 2018 case was settled, NSCC continues to seek relief for the 2019, 2020 and 2021 tax years.
Another issue irrigation districts are watching is the continuing debate by the Idaho Public Utilities Commission and the Federal Energy Regulatory Commission to update PURPA and change policy requiring public utilities to purchase renewable energy from small electric producers.
New projects
NSCC is continuing to plan and install automated gates and flow-monitoring stations to conserve more water for shareholders. By minimizing return flows and using less water, they would be able to apply fewer chemicals to remove moss from the canals as well as bolster the next year’s water supply.
They are also planning on lining a second section of the main canal, another 4,000 feet from the Milner Dam bridge downstream. This will be accomplished using several funding sources, including a grant and loan from the Idaho Water Resources Board and a possible WaterSmart grant through the Bureau of Reclamation.
In addition, NSCC is furthering a feasibility study on a potentially new hydro-energy plant.
“At the end of the day, I’d like people to know that we take care of irrigation – first and foremost,” Hansten says. “That’s our business. Everything else is secondary to that.”
There will always be voices surrounding water allocation in a water-dependent, ag-dependent state like Idaho. The hope is that this article will educate those voices.
