Flathead Lake
Flathead Lake | ||
---|---|---|
člq̓etkʷ ( Primary inflows | ||
Primary outflows | Flathead River | |
Catchment area | 8,587 sq mi (22,240 km2) | |
Basin countries | United States | |
Max. length | 27.3 mi (43.9 km)[1] | |
Max. width | 15.5 mi (24.9 km)[1] | |
Surface area | 197 sq mi (510 km2)[2] | |
Average depth | 164.7 ft (50.2 m) | |
Max. depth | 370.7 ft (113.0 m)[1] | |
Water volume | 5.56 cu mi (23.2 km3)[1] | |
Residence time | 3.4 years | |
Shore length1 | 161.4 mi (259.7 km)[1] | |
Surface elevation | 2,894 ft (882 m) | |
Islands | Wild Horse Island; Cromwell, Bird, Bull, Little Bull, Melita, Shelter, Cedar, Mother-in-Law, Dream, Goose, Mary B, Rock Island; Douglas Islands | |
Settlements | 7 miles (11 km) south of Kalispell, Montana; Polson, Montana | |
1 Shore length is not a well-defined measure. |
Flathead Lake (
, United States.The lake is a remnant of the ancient, massive glacial dammed lake,
Geography
Located in the northwest corner of the state of Montana, 7 miles (11 km) south of Kalispell, it is approximately 30 miles (48 km) long and 16 miles (26 km) wide, covering 197 square miles (510 km2). It is a similar size as Minnesota's Mille Lacs Lake, but smaller than Red Lake. It is about half the area of San Francisco Bay (main bay). It is larger in surface area than Lake Tahoe, but it is much smaller in volume due to Tahoe's depth.[2] Flathead Lake has a maximum depth of 370.7 ft (113.0 m),[1] and an average of 164.7 ft (50.2 m). This makes Flathead Lake deeper than the average depths of the Yellow Sea or the Persian Gulf. Flathead Lake is in a scenic part of Montana, 30 miles (48 km) southwest of Glacier National Park and is flanked by two scenic highways, which wind along its curving shoreline. On the west side is U.S. Route 93, and on the east, is Route 35.
The lake is bordered on its eastern shore by the
production bordering or near the lake.The lake has an irregularly shaped shoreline and a dozen small islands cover 5.5 square miles (14 km2).
Geology
Flathead Lake lies at the southern end of a geological feature called the Rocky Mountain Trench. The trench, which formed with the Rocky Mountains, extends north into the southern Yukon as a straight, steep valley, which also holds the headwaters of the Columbia River. During the last ice age this trench was filled by an enormous glacier. As the glacier moved southward it carved out the trench. The Polson Moraine, near present-day Polson, Montana, marks the southernmost extent of the glacier during the last ice age and thus is the site of the glacier's terminal moraine.[9]
The large size of the Polson Moraine indicates that the glacier stalled here for many years before retreating. As the climate warmed, a portion of the glacier in the Mission Valley receded more slowly than the main body, which kept the lake basin from being filled with sediment. Eventually this ice also melted, forming a lake behind the moraine. Once the water reached the top of this
At one time, probably when the valley was partially filled by a glacier, the level of Flathead Lake was about 500 feet (150 m) higher and drained through the valley west of Elmo, Montana, which is at the end of Big Arm Bay, bottom center in the aerial photo above. Water carved out a wide, flat-bottomed pass with a deeper, narrow channel at the south edge of the pass. The deeper channel and traces of the dry riverbed are still visible from Route 28.[citation needed]
Management
The Flathead River and the
The lake is downstream of
History
Once known as "Salish Lake", this body of water was named for the
The summer of 2023 saw abnormally low water levels.[17]
Fauna
Flathead Lake is home to a number of native and non-native fishes, and is managed cooperatively by both Montana Fish, Wildlife and Parks and the Confederated Salish and Kootenai Tribes. The lake is inhabited by the native bull trout and cutthroat trout, as well as the non-native lake trout, yellow perch, and lake whitefish. Local residents have reported sighting other aquatic fauna in the lake as well, such as sturgeon and the Flathead Lake Monster.[18]
The non-native opossum shrimp, (Mysis diluviana), were introduced by Montana Department of Fish, Wildlife and Parks in the Flathead drainage basin to encourage production of larger kokanee salmon; they migrated into Flathead Lake and have altered the ecosystem.[19]
Fishermen had introduced lake trout 80 years prior[when?] but remained at low densities until the non-native Mysis became established. The bottom-dwelling mysids eliminated a recruitment bottleneck for lake trout by providing a deep water source of food where little was available previously. Lake trout subsequently flourished on mysids; this voracious piscivore now dominates the lake fishery. The formerly abundant kokanee were extirpated, and native bull and westslope cutthroat trout are imperiled. Predation by Mysis has shifted zooplankton and phytoplankton community size structure. Bayesian change point analysis of primary productivity (27-y time series) showed a significant step increase of 55 mg C m−2 d−1 (i.e., 21% rise) concurrent with the mysid invasion, but little trend before or after despite increasing nutrient loading. Mysis facilitated predation by lake trout and indirectly caused the collapse of kokanee, redirecting energy flow through the ecosystem that would otherwise have been available to other top predators (bald eagles).[20]
Like the majority of other nonnative species, the lake trout (Salvelinus namaycush) became established in the lake from the late 1800s-early 1900s. The introduction of lake trout has placed increased pressure on the ecologically similar threatened native bull trout (Salvelinus confluentus).[21] The semi-annual "Mack Days" Lake Trout fishing contest aims to reduce the non-native "Mackinaw trout" or lake trout populations, as well as educate people about the Flathead Lake Fisheries Management Plan.[22][23] Since the inception of this event in 2002, over 402,000 lake trout have been harvested.[24]
- Native
- Cutthroat Trout
- Northern Pikeminnow
- Bull Trout
- Mountain Whitefish
- Westslope Cutthroat Trout
- Nonnative
- Brown Trout
- Lake Trout
- Golden Trout
- Yellowstone Cutthroat Trout
- Brook Trout
- Rainbow Trout
- Kokanee Salmon
- Northern Pike
- Yellow Perch
- Largemouth Bass
- Smallmouth Bass
- Sturgeon (sp)
In addition to these commonly-pursued game fish, the lake is also home to other native species that currently[when?] are not actively managed by government fish and wildlife agencies, including the longnose sucker (Catostomus catostomus), redside shiner (Richardsonius balteatus), and slimy sculpin (Cottus cognatus).
Panorama
Notes
- ^ a b c d e f g "Flathead Lake Facts". Flathead Lake Biological Station. University of Montana. Retrieved July 18, 2023.
- ^ ISBN 978-0-87371-120-3.
- S2CID 129648399. Retrieved July 27, 2022.
- ^ "The Cordilleran Ice Sheet and Missoula Floods". USGS: Glacial Lake Missoula. Retrieved July 27, 2022.
- ^ Kerr Dam, PPL Montana Archived 2016-10-16 at the Wayback Machine
- ^ Flathead Lake & Watershed Overview, Flathead Lakers Archived 2015-03-22 at the Wayback Machine
- ^ "MELITA ISLAND WOODLAND REHABILITATION PROJECT". Montana Council, Boy Scouts of America. n.d. Retrieved July 27, 2022.
- ^ "About Melita Island". Archived from the original on May 12, 2008. Retrieved April 5, 2008.
- ^ ISBN 9780878424153.
- ^ Drew, Micah (April 3, 2024). "Energy Keepers Receives Approval for Flathead Lake Level Variation". Flathead Beacon. Retrieved April 5, 2024.
- ^ Mepham, Andy (July 13, 2023). "Dam operators: Beginning of pattern of ever-decreasing levels in Flathead River Basin". KPAX News. Retrieved July 15, 2023.
- ^ "Reclamation's operation of Hungry Horse Dam" (Press release). Bureau of Reclamation. July 7, 2023. Retrieved July 19, 2023.
- ^ "Federal Columbia River Power System Water Management". NOAA Fisheries. May 10, 2022. Retrieved July 19, 2023.
- ^ Drew, Micah (July 15, 2023). "Technical Team Rejects Request to Raise Flathead Lake Levels with Hungry Horse Release". Flathead Beacon. Retrieved July 19, 2023.
- ^ Baldwin, Matt (March 16, 2024). "Flathead Basin dam operators defend management decisions". Daily Inter Lake. Retrieved March 17, 2024.
- Montana: The Magazine of Western History. 1 (1): 37–47.
- ^ Heston, Kate (November 15, 2023). "Zinke introduces legislation to regulate Flathead Lake water levels". Daily Inter Lake. Retrieved November 15, 2023.
- ^ Fugleberg, Paul (April 5, 2015). "Flathead Lake sturgeon catch still controversial". Missoulian. Retrieved April 10, 2015.
- ^ Bosworth, Brendan. "How Non-Native Shrimp Transformed The Ecosystem at Montana's Flathead Lake". Retrieved December 15, 2016.
- PMID 21199944.
- .
- ^ Backus, Perry (September 23, 2017). "Fall Mack Days starts this weekend at Flathead Lake". Missoulian. Retrieved September 24, 2017.
- ^ "Lake Trout Fishing". Mack Days. Retrieved September 24, 2017.
- ^ "Lake Trout Biology". Mack Daysm. Retrieved September 24, 2017.
References
- Alt, David. "The Making of Flathead Lake" in Profiles of Montana Geology: A layman's guide to the Treasure State. Butte, MT: Montana Bureau of Mines and Geology, 1984.