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99-543: It rises at the confluence of Rice Creek and a smaller unnamed stream in the southern part of the Lassen Volcanic National Park . The river flows east, receiving Warner Creek from the left, and passes the town of Chester . It then empties into Lake Almanor , which is formed by the Canyon Dam . After leaving the dam the river cuts south into a gorge, and turns southwest to receive Butt Creek from

198-497: A fish ladder to the hatchery, which is located on the north bank of the Feather River. The hatchery produces 10 million salmon smolt , along with 450,000 trout smolt, to stock in the river each year. The salmon smolt are released in two runs, with 20% for the spring run and 80% for the fall run. This facility has been successful enough that concern exists that salmon of hatchery stock are outcompeting remaining wild salmon in

297-708: A lava plateau. In the later Pliocene and into the Pleistocene , these basaltic flows were covered by successive thick and fluid flows of andesite lava, which geologists call the Juniper lavas and the Twin Lakes lavas. The Twin Lakes lava is black, porphyritic and has abundant xenocrysts of quartz (see Cinder Cone ). Another group of andesite lava flows called the Flatiron, erupted during this time and covered

396-401: A stratovolcano in the southwestern corner of the park during the Pleistocene . It was made of roughly alternating layers of andesitic lavas and tephra ( volcanic ash , breccia , and pumice ) with increasing amounts of tephra with elevation. At its height, Tehama was probably about 11,000 ft (3,400 m) high. Approximately 350,000 years ago its cone collapsed into itself and formed

495-654: A Mediterranean-influenced warm-summer Humid continental climate ( Dsb ). According to the United States Department of Agriculture , the Plant Hardiness zone at Kohm Yah-mah-nee Visitor Center at 6,736 ft (2,053 m) elevation is 6b with an average annual extreme minimum temperature of −0.2 °F (−17.9 °C). Since the entire park is located at medium to high elevations , the park generally has cool-cold winters and warm summers below 7,500 ft (2,286 m). Above this elevation,

594-562: A National Park on August 9, 1916. The 29 mi (47 km) Main Park Road was constructed between 1925 and 1931, just 10 years after Lassen Peak erupted. Near Lassen Peak the road reaches 8,512 ft (2,594 m), making it the highest road in the Cascade Mountains. It is not unusual for 40 ft (12 m) of snow to accumulate on the road near Lake Helen and for patches of snow to last into July. In October 1972,

693-412: A community less diverse than the mixed-conifer forest. Common plants include satin lupine , woolly mule's-ears and pinemat manzanita . Subalpine areas include the upper limit for the growth of standing trees. From 8,000 feet to treeline, plants are fewer in overall number with exposed patches of bare ground providing a harsh environment. Rock spirea , lupin , Indian paintbrush , and penstemon are

792-562: A concrete secant cutoff wall for the emergency spillway. The cost estimate at this point is over $ 500 million. In October 2017, hairline cracks were found in the rebuilt spillway. Things that added to the cost included relocating power lines, dredging the river downstream of the dam, as well as the discovery that the bedrock under the spillway was weak, necessitating deeper excavations and more concrete. The DWR commissioned an independent board of consultants (BOC) to review and comment on repairs to Oroville Dam. Memoranda (reports) prepared by

891-415: A failure, known as 'loss of crest control'." FERC water agencies responsible for the cost of the upgrades said this was unnecessary and that concerns were overblown. In 2006, a senior civil engineer sent a memorandum to his managers stating, "The emergency spillway meets FERC's engineering guidelines for an emergency spillway", and "The guidelines specify that during a rare flood event, it is acceptable for

990-420: A few of the rugged members of this community. Trees in this community include whitebark pine and mountain hemlock. Species that are typically found in these forested areas are black bear , red fox , mule deer , marten , cougar , brown creeper , a variety of chipmunk species, raccoon , mountain chickadee , pika , a variety of squirrel species, white-headed woodpecker , coyote , bobcat , weasel ,

1089-605: A major dam on the Feather River at Oroville, and aqueducts and pumping plants to transfer stored water to destinations in central and southern California. The proposed project was strongly opposed by voters in Northern California and parts of Southern California that received water from the Colorado River , but was supported by other Southern Californians and San Joaquin Valley farmers. However, major flooding in

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1188-594: A motion with the Federal Energy Regulatory Commission (FERC) urging federal officials to require that the dam's emergency spillway be armored with concrete, rather than remain as an earthen spillway, as it did not meet modern safety standards. "In the event of extreme rain and flooding, fast-rising water would overwhelm the main concrete spillway, then flow down the emergency spillway, and that could cause heavy erosion that would create flooding for communities downstream, but also could cause

1287-738: A pack consisting of a breeding pair and at least one offspring was reported within Lassen Volcanic Park by the California Department of Fish and Wildlife. The pack was likely formed by dispersing members from the Lassen Pack, which lives within Lassen County outside of the national park, and marks the first modern presence of wolves within the park itself. In the Cenozoic , uplifting and westward tilting of

1386-529: A portion of the park was designated as Lassen Volcanic Wilderness by the US Congress (Public Law 92-511). The National Park Service seeks to manage the wilderness in keeping with the Wilderness Act of 1964, with minimal developed facilities, signage, and trails. The management plan of 2003 adds that, "The wilderness experience offers a moderate to high degree of challenge and adventure." In 1974,

1485-493: A red fir, Abies magnifica ( 7 ) potential vegetation type with a California Conifer Forest ( 2 ) potential vegetation form. Lying at the northern end of the Sierra Nevada forests ecoregion, Lassen Volcanic National Park preserves a landscape nearly as it existed before Euro-American settlement: its 27,130 acres (10,980 ha) of old growth include all of its major forest types. At elevations below 6,500 feet

1584-410: A series of minor to major eruptions occurred on Lassen. These events created a new crater, and released lava and a great deal of ash . Fortunately, because of warnings, no one was killed, but several houses along area creeks were destroyed. Because of the eruptive activity, which continued through 1917, and the area's stark volcanic beauty, Lassen Peak, Cinder Cone and the area surrounding were declared

1683-522: A significant increase in volcanic activity be detected, the USGS will immediately deploy scientists and specially designed portable monitoring instruments to evaluate the threat. In addition, the National Park Service (NPS) has developed an emergency response plan that would be activated to protect the public in the event of an impending eruption. A downhill skiing site operating in the area

1782-666: A state water system geared primarily towards agriculture. A new study of California's water supplies by the Division of Water Resources (now California Department of Water Resources , DWR) was carried out under an act of the California State Legislature in 1945. In 1951, California State Engineer A. D. Edmonston proposed the Feather River Project, the direct predecessor to the SWP, which included

1881-580: A terrible height" and "burning lava running down the sides" in the area of Cinder Cone. As late as 1859, a witness reported seeing fire in the sky from a distance, attributing it to an eruption. Early geologists and volcanologists who studied the Cinder Cone concluded the last eruption occurred between 1675 and 1700. After the 1980 eruption of Mount St. Helens , the United States Geological Survey (USGS) began reassessing

1980-461: A third-party expert to improve the safety of the river valve outlet system (RVOS) and make it operational again. In 2014, DWR embarked on an accelerated refurbishment program to respond to concerns about operational needs during the ongoing drought. The system was mostly refurbished and was used during 2014 and 2015 to meet Endangered Species Act temperature requirements for the Feather River. Some additional refurbishments were being made to portions of

2079-419: A two-mile (3.2 km) wide caldera after it emptied its throat and partially did the same to its magma chamber in a series of eruptions. One of these eruptions occurred where Lassen Peak now stands, and consisted of fluid, black, glassy dacite , which formed a layer 1,500 ft (460 m) thick (outcroppings of which can be seen as columnar rock at Lassen's base). During glacial periods (ice ages) of

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2178-459: A variety of mouse species, long-toed salamander , skunk , and a wide variety of bat species. Areas such as Reflection Lake attract waterfowl, including Canada geese, great blue heron, snowy egret, and kingfisher. Lassen Volcanic Park is home to the Sierra Nevada red fox in particular, one of the rarest mammals in California. 20 individuals have been identified in the park, making it

2277-567: Is a cinder cone volcano and associated lava flow field that last erupted about 1650. It created a series of basaltic andesite to andesite lava flows known as the Fantastic Lava Beds. There are four shield volcanoes in the park; Mount Harkness (southwest corner of the park), Red Mountain (at south-central boundary), Prospect Peak (in northeast corner), and Raker Peak (north of Lassen Peak). All of these volcanoes are 7,000–8,400 feet (2,133–2,560 m) above sea level and each

2376-402: Is accessible via State Routes 89 and 44 . SR 89 passes north–south through the park, beginning at SR 36 to the south and ending at SR 44 to the north. SR 89 passes immediately adjacent to the base of Lassen Peak. There are five vehicle entrances to the park: the north and south entrances on SR 89; and unpaved roads entering at Drakesbad and Juniper Lake in the south, and at Butte Lake in

2475-533: Is also the southernmost non-extinct volcano of the Cascade Range (specifically, the Shasta Cascade part of the range). The 10,457 ft (3,187 m) tall volcano sits on the north-east flank of the remains of Mount Tehama , a stratovolcano that was a thousand feet (305 m) higher than Lassen and 11 to 15 mi (18 to 24 km) wide at its base. After emptying its throat and partially doing

2574-521: Is available. The pump-generators at Hyatt can lift up to 5,610 cubic feet per second (159 m /s) into Lake Oroville (with a net consumption of 519 MW), while the six turbines combined use a flow of 16,950 cu ft/s (480 m /s) at maximum generation. Since 1969, the Hyatt plant has worked in tandem with an extensive pumped-storage operation comprising two offstream reservoirs west of Oroville. These two facilities are collectively known as

2673-542: Is just north of Lassen Peak. Phreatic (steam explosion) eruptions, dacite and andesite lava flows and cinder cone formation have persisted into modern times. There are active hot springs and mud pots in the Lassen area. Some of these springs are the site of occurrence of certain extremophile micro-organisms, that are capable of surviving in extremely hot environments. [REDACTED]  This article incorporates public domain material from websites or documents of

2772-440: Is released. During the winter and early spring, Lake Oroville is required to have at least 750,000 acre⋅ft (240 billion US gal; 930 billion L), or a fifth of the reservoir's storage capacity, available for flood control. The dam is operated to maintain an objective flood-control release of 150,000 cubic feet per second (4,200 m /s), which may be further reduced during large storms when flows below

2871-458: Is still active with boiling mud pots , fumaroles , and hot springs . Lassen Volcanic National Park started as two separate national monuments designated by President Theodore Roosevelt in 1907: Cinder Cone National Monument and Lassen Peak National Monument. Starting in May 1914 and lasting until 1917, a series of minor to major eruptions occurred on Lassen. Because of the eruptive activity and

2970-472: Is studded with small lakes, but it boasts few streams. Warner Valley, marking the southern edge of the Lassen Plateau, features hot spring areas (Boiling Springs Lake, Devils Kitchen, and Terminal Geyser). This forested, steep valley also has large meadows that have wildflowers in spring. Lassen Peak is made of dacite , an igneous rock , and is one of the world's largest plug dome volcanoes. It

3069-745: Is the longest reinforced concrete bridge in the US. The North Fork is heavily developed for hydroelectricity generation and is impounded by five dams, as part of three hydroelectric projects – the Upper North Fork Feather River Project , the Rock Creek-Cresta Hydroelectric Project and the Poe Hydroelectric Project . The system is so extensive that it has been dubbed the "Stairway of Power". The Feather River Canyon

North Fork Feather River - Misplaced Pages Continue

3168-433: Is topped by a cinder cone volcano. During ice ages , glaciers have modified and helped to erode the older volcanoes in the park. The center of snow accumulation and therefore ice radiation was Lassen Peak, Red Mountain, and Raker Peak. These volcanoes thus show more glacial scarring than other volcanoes in the park. Despite not having any glaciers currently, Lassen Peak does have 14 permanent snowfields. The park

3267-701: Is well known for high winds. The "Jarbo Winds", named for nearby Jarbo Gap, often blow down the canyon from the northeast. These katabatic winds are caused by high-pressure air over the Great Basin seeking a path through the Sierra Nevada to the low-pressure voids on the California coast. The 2018 Camp Fire , the deadliest wildfire in California's history, was driven into Paradise by these winds. Meteorological records show 36 days since 2003 with gusts of 100 mph or more, up to 200 mph. The North Fork Feather Watershed (USGS Huc 18020121) extends from

3366-602: The Cascade Range . Lassen Volcanic National Park is one of the few areas in the world where all four types of volcanoes can be found: plug dome , shield , cinder cone , and stratovolcano . The source of heat for the volcanism in the Lassen area is subduction of the Gorda Plate diving below the North American Plate off the Northern California coast. The area surrounding Lassen Peak

3465-618: The Central Valley Project , a federal water project that would develop the Sacramento and San Joaquin River systems for irrigation of the highly fertile Central Valley . However, after the end of World War II in 1945, the state experienced an economic boom that led to rapid urban and commercial growth in the central and southern portions of the state, and it became clear that California's economy could not depend solely on

3564-731: The Great Basin Divide triple point of the Feather, Pit, and Susan Rivers . The divide arcs southeast to Pegleg Mountain and along 13 mi (21 km) of the Sierra Crest to the triple point with the East Branch North Fork Feather River on the east slope of Indicator Peak ( 40°00′43″N 120°11′15″W  /  40.012069°N 120.187554°W  / 40.012069; -120.187554 ). Downstream of Shasta and Lassen counties,

3663-498: The National Park Service took the advice of the USGS and closed the visitor center and accommodations at Manzanita Lake . The Survey stated that these buildings would be in the way of a rockslide from Chaos Crags if an earthquake or eruption occurred in the area. An aging seismograph station remains. However, a campground, store, and museum dedicated to Benjamin F. Loomis stands near Manzanita Lake, welcoming visitors who enter

3762-551: The National Park Service . Oroville Dam Oroville Dam is an earthfill embankment dam on the Feather River east of the city of Oroville, California , in the Sierra Nevada foothills east of the Sacramento Valley . At 770 feet (235 m) high, it is the tallest dam in the U.S. and serves mainly for water supply, hydroelectricity generation, and flood control. The dam impounds Lake Oroville ,

3861-779: The Oroville–Thermalito Complex . Water is diverted into the upper Thermalito reservoir (Thermalito Forebay) via the Thermalito Diversion Dam on the Feather River. During periods of off-peak power use, surplus energy generated at Hyatt is used to lift water from Thermalito's lower reservoir (the Thermalito Afterbay) to the forebay, which releases water back into the afterbay to generate up to 114 MW of power at times of high demand. The Hyatt and Thermalito plants produce an average of 2,200 gigawatt hours (GWh) of electricity each year, about half of

3960-615: The Sierra Nevada along with extensive volcanism generated huge lahars (volcanic-derived mud flows) in the Pliocene which became the Tuscan Formation . This formation is not exposed anywhere in the national park but it is just below the surface in many areas. Also in the Pliocene, basaltic flows erupted from vents and fissures in the southern part of the park. These and later flows covered increasingly large areas and built

4059-610: The anadromous migrations of Chinook salmon and steelhead trout in the Feather River. In 1967, in an effort to compensate for lost habitat, the DWR and the California Department of Fish and Game completed the Feather River Fish Hatchery. The Fish Barrier Dam, built in 1962, intercepts salmon and trout before they reach the base of the impassable Thermalito Diversion Dam and forces them to swim up

North Fork Feather River - Misplaced Pages Continue

4158-548: The emergency weir crest at 901 ft (275 m) and, at average storage capacity, the Lake Oroville level of 812 ft (247 m) . Lassen Volcanic National Park Lassen Volcanic National Park is a national park of the United States in northeastern California . The dominant feature of the park is Lassen Peak , the largest plug dome volcano in the world and the southernmost volcano in

4257-651: The 1950s prompted the 1957 passage of an emergency flood-control bill that provided sufficient funding for construction for a dam at Oroville – regardless of whether it would become part of the SWP. Groundbreaking on the dam site occurred in May 1957 with the relocation of the Western Pacific Railroad tracks that ran through the Feather River Canyon. The Burns-Porter Act of the California Legislature, which authorized

4356-452: The BOC are posted at the DWR web site. The independent forensic team (IFT) was selected to determine the cause of the spillways incident, including effects of operations, management, structural design and geological conditions. According to its 2017–18 operations plan, the DWR maintained Lake Oroville at a lower-than-normal level to reduce the possibility that the spillway would have to be used

4455-467: The Feather River around the dam site. One of the tunnels was located at river level and was to carry normal water flows, while the second one was only to be used during floods. In May 1963, workers poured the last of 252,000 cu yd (6.8 million cu ft; 193,000 m ) of concrete that comprised the 128 ft (39 m) high cofferdam , to protect the construction site from floods. This structure later served as an impervious core for

4554-493: The Feather River, after days of heavy rain, reached a peak flow of 250,000 cu ft/s (7,100 m /s) above the Oroville Dam site. The water rose behind the partially completed embankment dam and nearly overtopped it, while a maximum of 157,000 cu ft/s (4,400 m /s) poured from the diversion tunnels. This Christmas flood of 1964 was one of the most disastrous floods on record in Northern California, but

4653-560: The Feather's confluence with the Yuba River exceed 300,000 cubic feet per second (8,500 m /s). In the particularly devastating flood of 1997, inflows to the reservoir hit more than 331,000 cubic feet per second (9,400 m /s), but dam operators managed to limit the outflow to 160,000 cubic feet per second (4,500 m /s), sparing large regions of the Sacramento Valley from flooding. Oroville Dam completely blocks

4752-920: The North Fork headwaters south-southwest to the Lower Feather Watershed. The headwaters are in the Shasta Cascades and the northern Sierras along the Pit River and Eagle - Honey watersheds. The drainage divide for the headwaters begins in Shasta County at the Lassen Peak quadruple watershed point of East Sulpher Creek (Mill-Big Chico), Manzanita Creek (Upper Cow-Battle watershed), Lost Creek (Lower Pit River ), and Kings Creek (North Fork Feather). The headwater divide extends in an arc east to Lassen County , then to

4851-535: The RVOS and were expected to conclude in early 2017. The spillway cracked in 2013. A senior civil engineer with the DWR was interviewed by the Sacramento Bee , and explained, "It’s common for spillways to develop a void because of the drainage systems under them", and "There were some patches needed and so we made repairs and everything checked out." In July 2015, the state Division of Safety of Dams inspected

4950-439: The SWP, was not passed until November 8, 1960, and only by a slim margin. Engineer Donald Thayer of the DWR was commissioned to design and head construction of Oroville Dam, and the primary work contract was awarded to Oro Dam Constructors Inc., a joint venture led by Oman Construction Co. Two concrete-lined diversion tunnels, each 4,400 ft (1,341 m) long and 35 ft (11 m) in diameter, were excavated to channel

5049-426: The area's stark volcanic beauty, Lassen Peak, Cinder Cone, and the area surrounding were established as a National Park on August 9, 1916. The Atsugewi have inhabited the area since long before white settlers first saw Lassen. They knew that the peak was full of fire and water and thought it would one day blow itself apart. European immigrants in the mid-19th century used Lassen Peak as a landmark on their trek to

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5148-404: The area—more than $ 1.3 billion between 1987 and 1999. The dam stops fish migration up the Feather River and the controlled flow of the river; as a result, the Oroville Dam has affected riparian habitat. Multiple attempts at trying to counter the dam's impacts on fish migration have included the construction of a salmon / steelhead fish hatchery on the river, which began shortly after the dam

5247-526: The center of Tehama's now-gone cone. Other geothermal areas in the caldera are Little Hot Springs Valley, Diamond Point (an old lava conduit), and Bumpass Hell (see Geothermal areas in Lassen Volcanic National Park ). The magma that fuels the volcanoes in the park is derived from subduction off the coast of Northern California. Cinder Cone and the Fantastic Lava Beds , located about 10 mi (16 km) northeast of Lassen Peak,

5346-656: The climate is harsh and cold, with cool summer temperatures. Precipitation within the park is high to very high due to a lack of a rain shadow from the Coast Ranges . The park gets more precipitation than anywhere else in the Cascades south of the Three Sisters . Snowfall at the new visitor center near the southwest entrance at 6,700 ft (2,040 m) is around 430 in (1,090 cm) despite facing east. Up around Lake Helen , at 8,200 ft (2,499 m)

5445-439: The collision started a forest fire that burned 100 acres (40 ha) before it could be extinguished. The crash delayed construction of the dam by a week while the train wreckage was cleared. Overall, 34 men died in the construction of the dam. Oroville Dam was designed to withstand the strongest possible earthquake for the region, and was fitted with hundreds of instruments that serve to measure water pressure and settlement of

5544-489: The completed dam. With the cofferdam in place, an 11-mile (18 km) rail line was constructed to move earth and rock to the dam site. An average of 120 train cars ran along the line each hour, transporting fill that was mainly excavated from enormous piles of hydraulic mining debris that was washed down by the Feather River after the California Gold Rush . On December 22, 1964, disaster nearly struck when

5643-590: The country's largest underground power station . Since its completion in 1968, the Oroville Dam has allocated the flow of the Feather River from the Sacramento-San Joaquin Delta into the SWP's California Aqueduct , which provides a major supply of water for irrigation in the San Joaquin Valley , as well as municipal and industrial water supplies to coastal Southern California , and has prevented large amounts of flood damage to

5742-583: The crater in the main spillway was carried downstream, and caused damage to the Feather River Fish Hatchery due to high turbidity . Although engineers had hoped that using the damaged spillway could drain the lake enough to avoid use of the emergency spillway, they were forced to reduce its discharge from 65,000 cu ft/s (1,800 m /s) to 55,000 cu ft/s (1,600 m /s) due to potential damage to nearby power lines. Shortly after 8:00 pm on February 11, 2017,

5841-672: The dam spillway visually "from some distance" and did not walk it. The rainy season of 2016–2017 was Northern California's wettest winter in over 100 years . Heavy rainfall resulted in record inflows from the Feather River, and the spillway was opened in January to relieve pressure on Oroville Dam. After a second series of heavy storms in February, the spillway flow was increased to 50,000 cu ft/s (1,400 m /s), and on February 7, DWR employees noticed an unusual flow pattern. This halted spillway outflow, and DWR brought engineers onto

5940-545: The dominant vegetation community is the mixed conifer forest. ponderosa and Jeffrey pines , sugar pine , and white fir form the forest canopy for this rich community that also includes species of manzanita , gooseberry , and Ceanothus . Common wildflowers include iris , spotted coralroot , pyrola , violets , and lupin . Above the mixed-conifer forest is the major community of the red fir forest. Between elevations of 6,500 and 8,000 feet, red fir, western white pine , mountain hemlock , and lodgepole pine dominate

6039-560: The earth fill used in its construction, earning it the nickname "the dam that talks back". (A M L 5.7 earthquake in the Oroville area in 1975 is believed to have been caused by induced seismicity from the weight of the Oroville Dam and reservoir on a local fault line. ) The embankment was finally topped out on October 6, 1967, with the last of 155 million short tons (140.6 million tonnes ) of material that took over 40,000 train trips to transport. On May 4, 1968, Oroville Dam

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6138-401: The emergency spillway began carrying water for the first time since the dam's construction in 1968. The water flowed directly onto the earthen hillside below the emergency spillway, as designed. However, headward erosion of the emergency spillway threatened to undermine and collapse the concrete weir . On February 12, an evacuation was ordered for low-lying areas, due to possible failure of

6237-403: The emergency spillway to sustain significant damage." At around 7:30   am on July 22, 2009, several workers were deep below the reservoir operating flow controls to test a river valve chamber in the Oroville Dam. When the flow reached 85%, suction pulled a breakaway wall downstream into a 35-foot (11 m) diversion tunnel, cutting lights and nearly sending three workers to their deaths in

6336-422: The emergency spillway. The flow over the main spillway was increased to 100,000 cu ft/s (2,800 m /s) to try to slow erosion of the emergency spillway. By 8:00 pm on the evening of February 12, the increased flow had lowered the water level, causing the emergency spillway to stop overflowing. On February 14, the sheriff of Butte County lifted the mandatory evacuation order. On May 19, 2017,

6435-424: The fertile Sacramento Valley . One of the guides to these immigrants was a Danish blacksmith named Peter Lassen , who settled in Northern California in the 1830s. Lassen Peak was named after him. Nobles Emigrant Trail was later cut through the park area and passed Cinder Cone and the Fantastic Lava Beds . Inconsistent newspaper accounts reported by witnesses from 1850 to 1851 described seeing "fire thrown to

6534-545: The fire entered Lassen Volcanic National Park near Juniper Lake and the entire park was closed for safety. The town of Mineral , including park headquarters, was forced to evacuate. Structure loss occurred at the Drakesbad Guest Ranch and at cabins near Juniper Lake. The Dixie Fire's advance northward was slowed by the 2012 Reading Fire footprint, but the Dixie Fire ultimately burned 73,240 acres within

6633-486: The following winter. In a second phase of spillway repairs in 2018–19, temporary repairs on the main spillway done during phase one were being torn out and replaced with steel-reinforced structural concrete. On April 2, 2019, due to heavy rainfall upstream, the DWR began releasing water over the newly reconstructed spillway at a rate of 8,300 cubic feet per second (240 m /s). Releases were increased to 25,000 cubic feet per second (710 m /s) on April 7 to test how

6732-409: The future. Due to the low precipitation in the catchment area, water levels were below normal beginning in 2020. In August 2021, the Hyatt power plant had to be shut down because the water level fell below its water inlets. After falling to a record low of 22% capacity by September 30, winter storms increased the lake level by December and the plant was restarted on January 4, 2022. Construction of

6831-442: The future. On November 1, 2017, DWR director Grant Davis said, "Lake Oroville's main spillway is indeed ready to safely handle winter flows if needed". While this completes phase 1 of the construction, there remained a phase 2 to be completed in 2018. The second phase would include rebuilding the top section of the spillway (which was not rebuilt this season), putting slabs over the roller compacted concrete section, and constructing

6930-453: The incomplete dam was able to reduce the peak flow of the Feather River by nearly 40%, averting massive damage to the area. Ten months later, four men died in a tragic accident on the construction rail line. On October 7, 1965, two 40-car work trains, one fully loaded and the other empty, collided head-on at a tunnel entrance, igniting 10,000 US gallons (38,000 L) of diesel fuel, completely destroying two locomotives. The burning fuel from

7029-563: The largest known Sierra Nevada red fox population. A repopulation of wolves in California began in late December 2011. A northwestern wolf pack originally from Oregon known as the Lassen Pack inhabits the forest surrounding this national park. Other residential California wolves are the Beckwourth and Whaleback packs. The Shasta pack, which formerly was in the forest near this park, no longer appears to be extant. In 2024,

7128-480: The lava dome pushed its way up, it shattered overlaying rock, which formed a blanket of talus around the emerging volcano. Lassen rose and reached its present height in a relatively short time, probably in as little as a few years. Lassen Peak has also been partially eroded by Ice Age glaciers, at least one of which extended as much as 7 mi (11 km) from the volcano itself. Since then, smaller dacite domes formed around Lassen. The largest of these, Chaos Crags ,

7227-944: The majority of the North Fork Feather Watershed area is in Plumas County . The west divide of the watershed is along the Mill-Big Chico Watershed, southward to the West Branch Feather River triple point. The southeast divide of the North Fork Feather Watershed is the watershed of the East Branch to the triple point with the Middle Fork Feather River . The lowest elevations of the North Fork Feather Watershed are in Butte County , with

7326-638: The northeast. The park can also be accessed by trails leading in from the Caribou Wilderness to the east, as well as the Pacific Crest Trail , and two smaller trails leading in from Willow Lake and Little Willow Lake to the south. The segment of SR 89 through the park is typically closed during the winter due to very heavy snowfall and snowpack. According to the Köppen climate classification system, Lassen Volcanic National Park has

7425-461: The park features great lava pinnacles (huge mountains created by lava flows), jagged craters, and steaming sulfur vents. It is cut by glaciated canyons and is dotted and threaded by lakes and rushing clear streams . The eastern part of the park is a vast lava plateau more than one mile (1.6 km) above sea level. Here, small cinder cones are found (Fairfield Peak, Hat Mountain, and Crater Butte). Forested with pine and fir , this area

7524-613: The park from the northwest entrance. After the Mount St. Helens eruption, the USGS intensified its monitoring of active and potentially active volcanoes in the Cascade Range. Monitoring of the Lassen area includes periodic measurements of ground deformation and volcanic-gas emissions and continuous transmission of data from a local network of nine seismometers to USGS offices in Menlo Park, California . Should indications of

7623-451: The park via in-road inductive loops at all vehicle entrances. Buses and other non-reportable vehicles are subtracted from the vehicle count, which is then multiplied by three, an estimate of the number of visitors per vehicle. The park is located near the northern end of the Sacramento Valley , near the cities of Redding and Susanville . It is located in portions of Shasta , Lassen , Plumas , and Tehama counties. The western part of

7722-432: The park—approximately 69% of the park's total area. 12,845 acres, or 18% of that area, burned at a severity that left the landscape unchanged. 34,450 acres, or 49% of the burned area in the park, burned at a low-to-moderate severity. The remaining 23,493 acres, or 33% of the area burned by the Dixie Fire in Lassen Volcanic National Park, burned at a high severity. The NPS tracks Lassen visitors by counting vehicles entering

7821-564: The potential risk of other active volcanic areas in the Cascade Range . Further study of Cinder Cone estimated the last eruption occurred between 1630 and 1670. Recent tree-ring analysis has placed the date at 1666. The Lassen area was first protected by being designated as the Lassen Peak Forest Preserve. Lassen Peak and Cinder Cone were later declared as U.S. National Monuments in May 1907 by President Theodore Roosevelt . Starting in May 1914 and lasting until 1921,

7920-627: The power necessary to drive the pumps that lift the water in the aqueduct from the delta into the valley, and then from the valley over the Tehachapi Mountains into coastal Southern California. Water and power from the dam contribute to the irrigation of 755,000 acres (306,000 ha) in the arid San Joaquin Valley Westside and municipal supplies to some 25 million people. At least 2.8 million acre⋅ft (910 billion US gal; 3.5 trillion L) of water

8019-480: The present Wisconsinan glaciation , glaciers have modified and helped to erode the older volcanoes in the park, including the remains of Tehama. Many of these glacial features, deposits and scars, however, have been covered up by tephra and avalanches, or were destroyed by eruptions. Roughly 27,000 years ago (older data gave an age of 18,000 years), Lassen Peak started to form as a dacite lava dome quickly pushed its way through Tehama's former north-eastern flank. As

8118-550: The right. The East Branch North Fork Feather River , the North Fork's largest tributary, comes in next to Caribou Rd (40°00'49.9"N 121°13'32.4"W). It then flows southwards, through several hydroelectric dams, into the north arm of Lake Oroville. The fork's portion of the Feather River Canyon is notable as part of the Feather River Route , and the railroad's North Fork Bridge near the river's mouth

8217-511: The roaring current. One of the workers who was badly injured survived by clinging to a bent rail, where he was struck by tools and equipment being sucked into the tunnel. He was hospitalized for four days with head trauma, a broken leg and arm, cuts, and bruises. The California Division of the Occupational Health and Safety Administration (Cal OSHA) concluded opening the valves without an energy-dispersion ring, which reportedly

8316-424: The same to its magma chamber in a series of eruptions, Tehama either collapsed into itself and formed a two-mile (3.2 km) wide caldera in the late Pleistocene or was simply eroded away with the help of acidic vapors that loosened and broke the rock, which was later carried away by glaciers. Sulphur Works is a geothermal area in between Lassen Peak and Brokeoff Mountain that is thought to mark an area near

8415-485: The second-largest reservoir in California, capable of storing more than 3.5 million acre-feet (1.1 × 10 ^  US gal; 4.3 × 10  m ). Built by the California Department of Water Resources , Oroville Dam is one of the key features of the California State Water Project (SWP), one of two major projects passed that set up California's statewide water system . Construction

8514-495: The snowfall is around 600–700 in (1,520–1,780 cm), making it probably the snowiest place in California. In addition, Lake Helen gets more average snow accumulation than any other recording station located near a volcano in the Cascade range, with a maximum of 178 in (450 cm). Snowbanks persist year-round. According to the A. W. Kuchler U.S. Potential natural vegetation Types, Lassen Volcanic National Park has

8613-491: The southwestern part of the park's area. The park by this time was a relatively featureless and large lava plain. Subsequently, the Eastern basalt flows erupted along the eastern boundary of what is now the park, forming low hills that were later eroded into rugged terrain. Pyroclastic eruptions then started to pile tephra into cones in the northern area of the park. Mount Tehama (also known as Brokeoff Volcano) rose as

8712-449: The spillway failure, including a faulty drainage system, variations in concrete thickness, and corrosion in the structure's rebar". For 2018 the DWR planned to demolish and reconstruct the portion of the spillway which was undamaged by the flood, but which also has been identified as structurally defective. In addition, crews worked to extend a cutoff wall under the emergency spillway to prevent erosion should that structure be used again in

8811-445: The spillway performed in higher flows. They were decreased to 15,000 cubic feet per second (420 m /s) on April 9. The DWR released an assessment, dated October 1, 2020, concluding that Oroville Dam was suitable for continued safe and reliable operation. Meanwhile, the Federal Energy Regulatory Commission has demanded that California submit a plan by September 2022, for addressing the issue of greater amounts of rain predicted in

8910-450: The spillway to inspect its integrity. The engineers found a large area of concrete and foundation erosion. This erosion feature was too massive to repair without diverting water to the emergency spillway, and halted outflow along the main spillway for a period to fix the hole. High inflows to Lake Oroville forced dam operators to continue using the damaged spillway, causing additional damage. The spillway hole continued to grow. Debris from

9009-464: The spillway was shut down for the summer, to allow demolition and repair work to begin. The total cost of the repair was projected to exceed $ 400 million, with the $ 275 million primary contract awarded to Kiewit Construction . FEMA was expected to cover a large portion of the expenses. According to an independent forensics team led by John France, the exact cause of the spillway failure remains uncertain, though they identified "24 possible causes for

9108-507: The total power produced by the SWP's eight hydroelectric facilities. Water released from Oroville Dam travels down the Feather River before joining with the Sacramento River , eventually reaching the Sacramento-San Joaquin Delta , where the SWP's California Aqueduct diverts the fresh water for transport to the arid San Joaquin Valley and Southern California. Oroville–Thermalito hydroelectric facilities furnish about one-third of

9207-411: The underground Edward Hyatt Pump-Generating Plant was finished shortly after the completion of Oroville Dam. At the time, it was the largest underground power station in the United States, with three 132- megawatt (MW) conventional turbines and three 141 MW pump-generators for a total installed capacity of 819 MW. The Hyatt Powerplant is capable of pumping water back into Lake Oroville when surplus power

9306-441: Was absent, "created water flow with such great turbulence that it blocked an air vent and created a vacuum". It sanctioned the DWR with six citations, including five classified as serious, and the department was initially fined $ 141,375. Two of the "serious" citations were overturned on appeal. This river valve system was one of the first parts of the dam to be built when the dam project started in 1961, because its initial purpose

9405-687: Was closed in 1992. The last remaining part was the Lassen Chalet, located near the southwest entrance, which was finally demolished in 2005. The new Kohm Yah-mah-nee Visitor Center opened to the public at the same location in 2008. It was so named after the Mountain Maidu name for Lassen Peak. In 2021, the Dixie Fire burned large portions of the National Park, becoming the largest wildfire in park history. On August 5, 2021,

9504-538: Was completed. In February 2017, the main and emergency spillways threatened to fail , leading to the evacuation of 188,000 people living near the dam. After deterioration of the main spillway largely stabilized and the water level of the dam's reservoir dropped below the top of the emergency spillway, the evacuation order was lifted. The main spillway was reconstructed by November 1, 2018, and water releases were successfully tested, up to 25,000 cu ft/s (710 m /s), during April 2019. In 1935, work began on

9603-482: Was initiated in 1961, and despite numerous difficulties encountered during its construction, including multiple floods and a major train wreck on the rail line used to transport materials to the dam site, the embankment was topped out in 1967 and the entire project was ready for use in 1968. The dam began to generate electricity shortly afterwards with completion of the Edward Hyatt Power Plant , then

9702-456: Was officially dedicated by the state of California. Among the notable figures present were California governor Ronald Reagan , who spoke, Chief Justice (formerly California governor) Earl Warren , Senator Thomas Kuchel , and California Representative Harold T. "Bizz" Johnson . The dedication was accompanied by a week of festivities in nearby Oroville, attended by nearly 50,000 people. On October 17, 2005, three environmental groups filed

9801-407: Was to divert the river while the dam was under construction. After that, it served various purposes, including as a possible emergency release valve. Since the accident, DWR had implemented a standing order that prohibited the operation of the river outlet system and significantly limited access to the river valve chamber. Following the accident, DWR entered into a 2012 agreement with Cal OSHA to hire

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