The Falls Creek Hydroelectric project is a small electric power generating facility located near the South Santiam River, 25 miles east of Sweet Home, Oregon, in the Willamette National Forest. The Falls Creek project generates power from a small quantity of water falling 2,381 feet. It is a “high head” plant, and has one of the highest “head pressures” in the northwest.

Project Name Falls Creek
LIHI Certificate Number 4
LIHI Effective and
Expiration Dates
June 3, 2012
June 3, 2017
Owner Falls Creek H.P. Limited Partnership
State Oregon
Location Located on Falls Creek, 20 miles east of Sweet Home, in the Willamette National Forest, Oregon.
Installed Capacity 4.9 MW
Average Annual Generation 15,200,000 KWh
Facility Type Run-of-river
FERC No. 6661

The Falls Creek Project is a run-of-river project, making use of available stream flow. A low diversion on Falls Creek diverts excess water from a 5-foot deep pool, into the penstock pipe. Most of this excess water comes from rainfall in the fall and winter and snow runoff in the spring. The amount of stream flow during these periods is frequently greater than 50 cubic feet per second (cfs), and occasionally exceeds 200 cfs. The Falls Creek Project draws about 26 cfs of this flow. Between August and October, stream flow drops to less than one cfs. Because of the lack of excess water, the plant uses this time period for routine and preventative maintenance.

From the point where the water is diverted, Falls Creek continues to run 2.3 miles further to the South Santiam River. This section of the creek is very steep, containing no anadromous fish (salmon or steelhead). Along this stretch, only a few trout live in pools formed by falls. During operation of the project, sufficient water remains in Falls Creek beyond the diversion to maintain these pools.

Water is delivered through 7,380 feet of 30, 24, and 20-inch welded steel penstock, dropping 2,381 feet down the mountainside to the powerhouse on the south bank of the South Santiam River. The entire length of the pipe is buried, with natural vegetation allowed to cover the route, thus concealing it from sight. The project is located on Forest Service land. The powerhouse is located directly across the river from a campground. It was designed to blend into the natural environment and not impact campground users. This was successfully accomplished by earth sheltering, sound control, and screening with native vegetation.

When the water reaches the powerhouse, it creates a pressure of approximately 1030 psi. The Turbine Generator rotates at 1200 RPM, and generates 4.9 megawatts at full load. The plant output depends on the stream flow available for generation. The turbine spear valves are opened or closed to regulate flows to the turbine based on head level signals from the diversion that indicate the amount of water availability.

The power plant operates using a GE Fanuc 90-30 PLC control system with a head-end interface computer system called Lookout. The plant can be monitored, and re-started if necessary via remote control.

Power is generated at 4160 volts, then transformed to 20,800 volts for transmission via PacifiCorp’s local distribution lines. Power is sold to PacifiCorp under a 35-year operating agreement.


Certification History

July 12, 2012: The Falls Creek Hydroelectric Project continues to meet the Low Impact Hydropower Certification Criteria, and has been recertified for a five year term, beginning June 3, 2012 and expiring June 3, 2017.

August 17, 2007: The Falls Creek Project has been recertified as low impact, continuing to meet LIHI’s eight environmentally rigorous criteria.  The Board’s vote to re-certify Falls Creek was unanimous. The effective certification date is May 1, 2007.

June 3, 2002: The Falls Creek Hydroelectric Project has become the first hydropower facility in Oregon to earn LIHI’s Low Impact Hydropower Certification. It is certified for a five year term, effective June 3, 2002 and expiring June 3, 2007.