Copco Lake

Copco Lake was created by the construction of Copco Number 1 Dam. This dam was completed in 1922 by the California Oregon Power Company (COPCO).^[2] COPCO was merged into Pacific Power and Light in 1961, and is now known as Pacificorp.^[4]

Copco Number 1 and Number 2 Dams were two of the four dams in the Klamath River Hydroelectric Project which were removed in the 2020s as part of the Klamath River Renewal Project. The social movement to Un-Dam the Klamath had been ongoing for over 20 years.^{[5][6][7][8][9]}

As of February 2016, the states of Oregon and California, the dam owners, federal regulators and other parties had reached an agreement to remove all four dams by the year 2020, pending approval by the Federal Energy Regulatory Commission (FERC).^[10] The plan was delayed in 2020 due to conditions placed on the project by FERC.^[11] In February 2022, the FERC released their final Environmental Impact Statement (EIS) on the dam's removal,^[12] and the dam was slated for removal in 2024.^[13] Copco 2 was demolished in 2023.

On January 23, 2024, the drawdown of water and sediment from Copco Lake was initiated via a detonation at the foot of Copco Number 1 Dam. The lake was expected to take three to four weeks to fully drain, at which point crews will plant native vegetation along the emerged riverbank. This was the last of the four dams to be breached as part of the Klamath River Renewal Project. Removal of the dam structure began in March 2024.^[14][15]

The lake was used for kayaking, fishing, swimming, windsurfing, power boating, and sailing. The surrounding area had facilities for picnicking and hiking.^[16] In the summer months, the lake often experienced large blooms of toxic cyanobacteria rendering the water unsafe for human contact or consumption.^[17]

Copco Number 1 Dam
Interactive map of Copco Number 1 Dam
Country	United States
Location	Siskiyou County, California
Coordinates	41°58′48″N 122°20′04″W / 41.98000°N 122.33444°W / 41.98000; -122.33444
Opening date	1922
Owner	PacifiCorp
Dam and spillways
Type of dam	Gravity
Impounds	Klamath River[2]
Height	132 feet (40 m)[2]
Length	415 feet (126 m)[2]
Elevation at crest	2,613 feet (796 m)[2]
Width (crest)	9 feet (2.7 m)[2]
Dam volume	70,312 cubic yards (53,757 m3)[2]
Reservoir
Creates	Copco Reservoir
Total capacity	77,000 acre-feet (95,000,000 m3)[2]
Catchment area	4,300 square miles (11,000 km2)[2]
Maximum length	3 miles (4.8 km)
Maximum width	1,200 yards (1,100 m)

Copco Number 1 Dam (National ID CA00323) was a gravity dam 415 feet (126 m) long and 132 feet (40 m) high, with 19.5 feet (5.9 m) of freeboard. PacifiCorp owned the dam prior to its transfer to the Klamath River Renewal Corporation in 2022.^[18] The dam was demolished in September 2024 as part of the Klamath River Renewal Project.^[19][3]

Copco Number 2 Dam was a gated diversion dam located just below Dam No. 1. The dam diverted most of the flow of the river, about 2,400 to 2,500 cu ft/s (68 to 71 m³/s), through a flume and tunnels to a 27-megawatt powerhouse 1.5 miles (2.4 km) downstream, on the upstream end of Iron Gate Reservoir. The diversion bypassed a canyon section of the Klamath River that historically consisted of some steep rapids. The dam was required to maintain a minimum release of 10 cu ft/s (0.28 m³/s) to prevent this stretch from being entirely dewatered. Because it had no effective storage capacity, Dam No. 2 depended entirely on the regulated flows released from Copco Lake.^[20] The dam was demolished in 2023 during the Klamath River Renewal Project.^[21]

• List of dams and reservoirs in California
• List of lakes in California