 | Flathead Lake is one of the 300
largest natural lakes in the world and is the largest natural
freshwater lake in the western United States. Of those large lakes,
Flathead is one of the cleanest. Studies at the Biological Station
show that water quality in Flathead Lake is among the best in the
world. |
| The Lake's major tributaries are
the Flathead and Swan Rivers. |
| Numerous small streams flow
directly into the Lake at its shoreline, particularly on the wetter
East Shore. |
| Kerr Dam is located at the outlet
of Flathead Lake in Polson, at the southern end. Regulation of
outflow by the dam maintains the Lake's level between 2,883 and 2,893
feet above sea level. If runoff conditions in the mountains don't
warrant flood threats, the Lake level is brought to 2,890 feet by the
end of May and to full pool by June 15. |
| Maximum flow in the Flathead
River generally occurs during spring freshet between May 15 and June
10, creating a plume of sediment that covers the Lake surface.
|
| Due to its massive volume and
normally active winds over the surface, Flathead Lake does not freeze
over most winters, although the bays often have winter ice cover. The
Lake did freeze over in the winters of 1978-79 (all winter), 1987-88
(all winter), 1988-89 (March only) and 1989-90 (January only).
|
| Open space on the shoreline
includes the National Wildlife Refuge on the North Shore and State
land managed by the Biological Station as a refuge on the South Shore
(Polson Bay). |
| Wildhorse
Island, near Big Arm Bay, is the largest island in the lake, at 2,100
acres, and managed by the Montana Department of Fish, Wildlife and
Parks as a wildlife refuge. It is noted for its herd of Rocky
Mountain Bighorn sheep and several wild horses. Native grasses and
flowers are abundant. |
| The Bird Islands near The Narrows
are State owned and are managed jointly by the Montana Department of
Fish, Wildlife and Parks and the Biological Station as a bird refuge.
Geese, osprey, herons and eagles frequent the Bird Islands.
|
| The name Yellow Bay was
derived from the yellow rock outcrop on the point which is Precambrian
without fossils. The outcrop belongs to the Algonkian substrata,
which also outcrops Glacier Park. |
| Flathead Lake Biological Station
was established in Bigfork in 1899 by Dr. Morton J. Elrod. The
Biological Station was moved to its present location in 1912 and is
currently operated as a year-round academic and research facility
mainly dealing with aquatic studies. |
| The first wagon trail (1880's)
from Polson to the north end of the Lake followed the west side of the
lake and was steep and hazardous. At some places, wagons had to be
lowered by ropes. |
| In 1911, work started from the
south end of the Lake to build an east shore road with the work
primarily done by convict labor. It was not completed until
September, 1946. |
| Flathead Lake is currently
described as oligomesotrophic (oligotrophic means being deficient in
plant nutrients while mesotrophic means having a moderate amount of
dissolved nutrients). |
| In spite of its renowned purity,
studies at the Bio Station show that water quality of Flathead Lake
has declined over the last decade due to the combined effects of
increased pollution from human sources, erosion of the shoreline
caused by dam operations and introduction of non-native biota (flora
and fauna). |
| Average surface temperatures of
the lake range from 2.3° C (36°F) in mid-January, to 13.5°C (56°F) in
mid-June, to 20.3°C (68°F) in mid-August. |
| Of the 25 fish species most
commonly found in the Flathead River-Lake ecosystem, 10 species are
native and 15 have been introduced. The native species include
redside shiner, peamouth minnow, squawfish minnow, largescale sucker,
longnose sucker, sculpin, bull trout, cutthroat trout, pygmy whitefish
and mountain whitefish. Lake trout, lake whitefish and yellow perch
are the most common non-natives and have increased in abundance since
1970 whereas native species have declined. |
