Eightmile Lake is a reservoir

lake A lake is an area filled with water, localized in a basin, surrounded by land, and distinct from any river or other outlet that serves to feed or drain the lake. Lakes lie on land and are not part of the ocean, although, like the much large ...

located on the eastern slope of Eightmile Mountain, in Chelan County in

Washington Washington commonly refers to: * Washington (state), United States * Washington, D.C., the capital of the United States ** A metonym for the federal government of the United States ** Washington metropolitan area, the metropolitan area centered o ...

. It is a reservoir lake formed along the beginning route of Eightmile Creek as it exits Jack Ridge. The lake is located approximately 10 miles from the city of

Leavenworth, Washington Leavenworth is a city in Chelan County, Washington, United States. It is part of the Wenatchee− East Wenatchee Metropolitan Statistical Area. The population was 2,263 at the 2020 census. The entire town center is modeled on a German Bavarian ...

. It is accessed by a 3.5-mile trail (USFS Trail No. 1552) that starts at USFS Road 7601 as it crosses over Eighmile Creek and makes a turn towards the Stuart and Culchuck Lake Trailhead where the road ends. Self-issued Alpine Lake Wilderness permit required for transit within the Eightmile Lake area.

Geography

Geology

Eighmile lake sits in a basing consisting of rocky soils and igneous

tonalite Tonalite is an igneous, plutonic ( intrusive) rock, of felsic composition, with phaneritic (coarse-grained) texture. Feldspar is present as plagioclase (typically oligoclase or andesine) with alkali feldspar making up less than 10% of the total ...

geology. The bedrock is about 3 feet from the surface. There is a large landslide area with boulders and other mass-wasting deposits located at the northeast shore of the lake. The trail to the lake consists of sandy loam and boulders. Eightmile Lake sits on a highly

glaciated A glacier (; ) is a persistent body of dense ice that is constantly moving under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires distinguishing features, such as ...

and semibarren alpine basin, surrounded by heather and other wildflowers and a coniferous presence primarily

larch Larches are deciduous conifers in the genus ''Larix'', of the family Pinaceae (subfamily Laricoideae). Growing from tall, they are native to much of the cooler temperate northern hemisphere, on lowlands in the north and high on mountains fur ...

pines.

Climate

Eightmile lake has a

hemiboreal Hemiboreal means halfway between the temperate and subarctic (or boreal) zones. The term is most frequently used in the context of climates and ecosystems. Botany A hemiboreal forest has some characteristics of a boreal forest to the north, and ...

climate. The average temperature is 2° C. The warmest month is August, with an average temperature of 17° C, and the coldest month is January, at an average of −10 ° C. The average rainfall is 705 millimeters per year. The wettest month is December, with 111 millimeters of rain, and the least in July, with 16 millimeters of rain.

Uses

Eightmile Lake is managed by the Icicle and Peshastin Irrigation Districts (IPID) to provide water storage for

irrigation Irrigation (also referred to as watering) is the practice of applying controlled amounts of water to land to help grow crops, landscape plants, and lawns. Irrigation has been a key aspect of agriculture for over 5,000 years and has been devel ...

. The lake captures water runoff from a 3,800-acre

drainage basin A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, ...

which gives the lake a high potential for refill, even during dry years. The reservoir is contained by a small

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use ...

consisting of a rock and masonry structure with stop logs and an earthen embankment section that extends from the rock-masonry/concrete structure to the hillside north of the dam. The dam is fitted with a low-level outlet pipeline and a slide gate at the outlet of the lake. Stop logs were first placed in a notch in the concrete portion of the dam up to the spillway crest to allow the lake to fill to an elevation of approximately 4,671 feet. This infrastructure allows for controlled releases of stored water to supplement flows into

Icicle Creek Icicle Creek is a nonNavigable stream in the U.S. state of Washington. It originates at Josephine Lake near the crest of the Cascade Range and flows generally east to join the Wenatchee River near Leavenworth. Icicle Creek's drainage basin is mo ...

and increase the water supply available during low flow periods, which typically occur during the late summer.

2017 fire

On August 11, 2017 lightning caused by a cold frontal passage that tracked through the

Alpine Lakes Wilderness The Alpine Lakes Wilderness is a large wilderness area spanning the Central Cascades of Washington state in the United States. The wilderness is located in parts of Wenatchee National Forest and Snoqualmie National Forest, and is approximately b ...

started a fire about 15 miles southwest of

. The fire expanded into the Stuart Lake and Eightmile drainages burning to the shoreline of Eightmile Lake damaging a large percentage of the lake's watershed. The fire has caused a potential change in runoff into the lake.

Restoration

In 2016, Chelan County and the

Washington State Department of Ecology The Washington State Department of Ecology (sometimes referred to simply as "Ecology") is the state of Washington's environmental regulatory agency. Created in February 1970, it was the first environmental regulation agency in the U.S. predating t ...

had proposed the Icicle Strategy plan to resolve the shortage of water supply that threatened

, fish habitat and passage, and

tribal The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide usage of the term in English is in the discipline of anthropology. This definition is contested, in part due to conflic ...

and non-tribal fisheries in the

subbasin region. The plan also managed to improve streamflow and water availability into the subbasin affected by the subsequent 2017 forest fires. In 2018, the plan was approved by the

. The Icicle Strategy also restored the dam infrastructure at Eightmile Lake, permitting higher levels of water storage. Although there were concerns for flooding in and around the areas surrounding the lake and the possibility of damaging trails and vegetation, the positive impacts outweighed the risks; habitat protection, fish passage, fish screening, and water conservation efficiencies. The earthen embankment portion of the dam was restored to reposition from erosion around the north side of the rock-masonry dam which had reduced its capacity of impounding water to the full level for which it was designed and at which it historically operated. Restorations raised the water level to an elevation of approximately 4,667 feet.

References

External links

* {{authority control Lakes of Chelan County, Washington Lakes of the Alpine Lakes Wilderness Okanogan National Forest