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Keoka Lake

Keoka Lake was originally called Thomas Pond, after Thomas Chamberlain who supposedly hid under a rock along the shore when he was chased by Native Americans. The northwestern side of the lake was settled in the late 1700s and soon became known as “The Flat.” Today, the lake is enjoyed by boaters, anglers, swimmers and sightseers.


Keoka Lake’s gravel and boulder shoreline provides excellent habitat for both smallmouth and largemouth bass. Although brook trout are stocked annually, oxygen levels in the deep, cool water during August and September are often below levels needed to sustain a healthy trout population. Keoka also supports populations of yellow perch, chain pickerel, hornpout, smelt, eel, white sucker, minnows and pumpkinseed sunfish.

  • Lake Surface

    460 acres
  • Watershed

    3,808 acres
  • Max. Depth

    42 feet
  • Elevation

    492 feet

Water Quality: 2022

The average Secchi disk reading for 2022 was 6.8 meters, which falls into the moderately clear range. The
average total phosphorus reading of 6.1 ppb falls into the moderate range. The average deep water phosphorus value was not significantly above surface water phosphorus values, which suggests phosphorus recycling is not problematic. The chlorophyll average of 3.5 ppb falls into the moderate range. Long-term trend analysis indicates chlorophyll concentrations in Keoka Lake are stable, total phosphorus concentrations are decreasing, and clarity readings are increasing. The average color reading for 2022 was 23.4 SPU, indicating that water in Keoka Lake is moderately colored.

2022 Water-testing summary

Keoka Lake’s surface water chlorophyll (ppb), phosphorus (ppb), and Secchi depth (meters) data comparison. Colored areas represent the long-term range of values, from minimum to maximum. Area thickness indicates frequency of measurements at that value. Area thickness increases as more measurements are reported at that value. The vertical black line represents the long-term average value. The large red dot represents 2022’s average value. The small red dots represent individual readings taken in 2022.

2022 average vs. long-term average

  • Clarity: Keoka Lake's 2022 average water clarity was within the 'moderately clear' range. Keoka Lake's long-term clarity trend is increasing, indicating deeper clarity readings over time.
  • Chlorophyll: Keoka Lake's 2022 average chlorophyll concentration was within the 'moderate' range. Keoka Lake's long-term chlorophyll trend is stable, indicating that chlorophyll concentrations in the water are neither higher nor lower over time.
  • Phosphorous: Keoka Lake's 2022 average phosphorous concentration was within the 'moderate' range. Deep water phosphorus values were not significantly above surface water phosphorus values indicating that phosphorus recycling was not an issue for Keoka Lake in 2022. Keoka Lake's long-term total phosphorus trend is decreasing, indicating less phosphorus in the water over time.

    Keoka Lake Watershed Project

    The Keoka Lake Watershed Project involved surveying, documenting and then fixing areas within the Keoka Lake Watershed that were eroding and causing a negative impact on Keoka’s water quality. During the survey portion, volunteers from the Keoka Lake Association and residents from within the watershed as well as staff from the Department of Environmental Protection, the Soil and Water Conservation District and LEA helped locate, map out and document 65 sites where erosion was occuring. This information was then compiled into the Keoka Lake survey report which functions as a landowner handbook and reference for future mitigation work. Based on evaluations made in the survey, priority sites were chosen and then construction and mitigation work began on these sites to correct ongoing erosion. As part of this project, water quality improvements were completed on Plummer Hill Road, Mill Hill Road, the Johnson Road, Loon Echo Drive, Kimball Trail, Keoka Campground, the Hawk Mountain access road, at the boat launch and on individual lots.

    Watershed Soils

    4 percent of soils in the watershed are type A soils. Type A soils tend to be well drained sands, loams, and gravels. When vegetation is removed and the soil is exposed they can be susceptible to erosion. Because they are often coarse with ample pore space, there is low runoff potential and water will not usually pool on them. These soils can be good places to site leach fields or infiltrate stormwater from a home or residence.

    2 percent of soils in the watershed are type B soils. B soils have moderate infiltration rates and fine to moderate texture and soil size. They are usually made up silts and loams. Although not as well drained as A soils, they can also be good places to site leach fields and infiltrate stormwater.

    71 percent of soils in the watershed are type C soils. C soils have low infiltration rates and typically have a layer that impedes the movement of water. These soils are made of sands, clays, and loams and are one of the most common soil types in western Maine.

    2 percent of soils in the watershed are type D soils. D soils have a high runoff potential and very low infiltration rates. Soils with a high water table, clay or other impervious layer near the surface are typically D soils. These soils are often associated with wetlands.

    10 percent of soils in the watershed are type C/D soils. C/D soils are a mix of these two soil types. They have fairly high runoff potential and low infiltration rates and often pool water.

    The remaining 11 percent of the watershed is taken up by the lake.

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