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Long Lake

View live data from LEA’s Long Lake Buoy in the North Basin of the Lake from May-November

Long Lake is the second largest water body in southern Maine and is part of the Presumpscot River drainage. It connects to Brandy Pond and Sebago Lake, making it popular with water-skiers and boaters. Activities on the Causeway in Naples include trips on the Songo River Queen paddleboat, seaplane rides, windsurfing and para-sailing.

Fishing

Long Lake supports a high quality black bass fishery and is one of the more popular lakes in southern Maine for bass angling tournaments. Other principal fisheries are landlocked Atlantic salmon, brown trout, chain pickerel, and white perch. Twelve other species also are present, including American eel, golden and common shiner, fallfish, white sucker, brown bullhead, burbot, lake and brook trout, pumpkinseed sunfish, yellow perch, and rainbow smelt. Each fall the lake is stocked with landlocked salmon and brown trout from the state hatcheries.

  • Lake Surface

    4,935 acres
  • Watershed

    33,871 acres
  • Max. Depth

    59 feet
  • Elevation

    267 feet

Water Quality: 2019

North Basin: The average Secchi disk reading for 2019 was 6.02 meters, fell into the moderately clear range, and was shallower than the long-term average of 6.19 meters. The average total phosphorus reading of 6.88 ppb fell into the moderate range and was less than the long-term average of 7.46 ppb. Deep water phosphorus values fell into the low range. The chlorophyll-a average of 2.75 ppb fell into the moderate range and was less than the long-term average of 3.01 ppb. Long-term trend analysis indicates chlorophyll–a concentrations in Long Lake’s north basin are stable, total phosphorus concentrations are stable, and clarity readings are stable. The average color reading for 2019 was 26 SPU, indicating that water in Long Lake’s north basin is highly colored. Suitable fish habitat was present through July but became unsuitable in August through September.

Middle Basin: The average Secchi disk reading for 2019 was 6.11 meters, fell into the moderately clear range, and was shallower than the long-term average of 6.30 meters. The average total phosphorus reading of 5.88 ppb fell into the moderate range and was less than the long-term average of 6.67 ppb. Deep water phosphorus values fell into the low range. The chlorophyll-a average of 2.63 ppb fell into the moderate range and was less than the long-term average of 2.92 ppb. Long-term trend analysis indicates chlorophyll–a concentrations in Long Lake’s middle basin are stable, total phosphorus concentrations are stable, and clarity readings are stable. The average color reading for 2019 was 27.89 SPU, indicating that water in Long Lake’s middle basin is highly colored. Suitable fish habitat was present through June but transitioned to marginal and then unsuitable habitat in July. Unsuitable fish habitat persisted through September.

South Basin: The average Secchi disk reading for 2019 was 6.34 meters, fell into the moderately clear range, and was shallower than the long-term average of 6.43 meters. The average total phosphorus reading of 5.75 ppb fell into the moderate range and was less than the long-term average of 6.32 ppb. Deep water phosphorus values fell into the low range. The chlorophyll-a average of 2.63 ppb fell into the moderate range and was less than the long-term average of 2.89 ppb. Long-term trend analysis indicates chlorophyll–a concentrations in Long Lake’s south basin are stable, total phosphorus concentrations are decreasing, and clarity readings are increasing. The average color reading for 2019 was 26.88 SPU, indicating that water in Long Lake’s south basin is highly colored. Suitable fish habitat was present through June, transitioned to marginal in July, and became unsuitable in August through September.

Water-testing summary

North Basin 2019 Quick Stats

Long Lake north basin surface water chlorophyll, phosphorus, and Secchi depth data summary. Colored boxes represent the long-term range of values, from minimum to maximum, obtained on Long Lake’s north basin. The line represents the long-term average value and the large dot represents 2019’s average value. The small red dots represent individual readings taken in 2019.

North Basin’s 2019 Average vs. Long-term Average:

Clarity: The average Secchi disk reading for 2019 was 6.02 meters, fell into the moderately clear range, and was shallower than the long-term average of 6.19 meters.

Chlorophyll: The chlorophyll-a average of 2.75 ppb fell into the moderate range and was less than the long-term average of 3.01 ppb

Phosphorus: The average total phosphorus reading of 6.88 ppb fell into the moderate range and was less than the long-term average of 7.46 ppb.

 

Middle Basin 2019 Quick Stats

 

Long Lake middle basin surface water chlorophyll, phosphorus, and Secchi depth data summary. Colored boxes represent the long-term range of values, from minimum to maximum, obtained on Long Lake’s middle basin. The line represents the long-term average value and the large dot represents 2019’s average value. The small red dots represent individual readings taken in 2019.

 

Middle Basin’s 2019 Average vs. Long-term Average:

Clarity: The average Secchi disk reading for 2019 was 6.11 meters, fell into the moderately clear range, and was shallower than the long-term average of 6.30 meters.

Chlorophyll: The chlorophyll-a average of 2.63 ppb fell into the moderate range and was less than the long-term average of 2.92 ppb.

Phosphorus: The average total phosphorus reading of 5.88 ppb fell into the moderate range and was less than the long-term average of 6.67 ppb.

 

South Basin 2019 Quick Stats

 

Long Lake’s south basin surface water chlorophyll, phosphorus, and Secchi depth data summary. Colored boxes represent the long-term range of values, from minimum to maximum, obtained on Long Lake’s south basin. The line represents the long-term average value and the large dot represents 2019’s average value.  The small red dots represent individual readings taken in 2019.

South Basin’s 2019 Average vs. Long-term Average:

Clarity: The average Secchi disk reading for 2019 was 6.34 meters, fell into the moderately clear range, and was shallower than the long-term average of 6.43 meters.

Chlorophyll: The chlorophyll-a average of 2.63 ppb fell into the moderate range and was less than the long-term average of 2.89 ppb.

Phosphorus: The average total phosphorus reading of 5.75 ppb fell into the moderate range and was less than the long-term average of 6.32 ppb.

Long Lake Project

This project aimed to significantly reduce erosion, sediment and phosphorus export into Long Lake. The grant began in the spring of 2006 and conservation practices that reduce erosion and polluted runoff were installed at over 27 sites throughout the watershed. Roads, beaches and residential properties were worked on during the project. A Youth Conservation Corp (YCC) was also formed which installed best management practices on numerous residential properties.

Long Lake TMDL report

A TMDL is a detailed watershed report with land use information and phosphorus loading estimates for a specific lake. The acronym TMDL stands for “Total Maximum Daily Load” and for Maine lakes it is used as a tool to assess and reduce phosphorus loading from within the entire watershed. Working with the Maine Association of Conservation Districts and Maine Department of Environmental Protection, LEA helped compile, organize and write a TMDL for Long Lake. The non-regulatory reports are intended to serve as a platform for future implementation work and watershed planning. It can also be used to compliment comprehensive planning updates. In addition to the land use inventory and phosphorus loading estimates, the reports contain water quality, fishery and soils information, a shoreline survey and recommendations for future best management practices in the watershed.

Watershed Soils

11 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.

58 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.

3 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.

2 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 23 percent of the watershed is taken up by the lake.

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