Tumbledown Pond
MIDAS 3512, Township 6 north of Weld, ME
One of western Maine’s most visited mountain ponds, Tumbledown Pond sits at just over 800 meters elevation between Tumbledown and Little Jackson summits. Our project has collected continuous water temperature data in Tumbledown Pond since the summer of 2007. We additionally collect thermal and dissolved oxygen profiles during each site visit, and collect samples for zooplankton and water chemistry analysis.
Water temperature data
General patterns in seasonal water temperature are similar in each year (e.g. consistent winter ice cover and stratified summer conditions), but the timing of major seasonal transitions and duration of the stratified periods and mixing events varies. Our high-resolution dataset allows us to evaluate this variability and understand the role of physiographic and climatic drivers that might explain the variation.
Water temperatures have been collected just below the surface and at the bottom of Tumbledown Pond every 30 minutes since the summer of 2007. These high-resolution temperature data allow us to capture the details of seasonal transitions and stratification patterns on the pond. For instance, temperature data from 2023 (below) illustrate winter and summer stratification, separated by periods of lake mixing in the spring and autumn. Following ice breakup in the spring, the surface waters warm quickly and then undergo subsequent warmer and cooler periods through the summer. The bottom of the lake warms during the summer, but temperatures remain lower than the surface and remain more stable until late September, when the first in a series of fall turnover events occurs. When ice cover is re-established on the pond, water at the bottom warms slowly from heat stored in the sediment, and winter stratification is re-established.
Site visit snapshot
Summer stratification and dissolved oxygen
Profile data collected during a field visit in June 2024 provide a snapshot of conditions in Tumbledown Pond. Water temperatures (left panel) show a warm surface and transition to cool temperatures at the thermocline. Dissolved oxygen (right panel) values show slightly higher concentrations below the thermocline, as one would expect in cooler water.
Year-to-year summer water temperature
Surface vs bottom variability
The daily average water temperatures at the surface and bottom of Tumbledown Pond from June-August across reveal different patterns across years. There is a lot of short-term variability in surface temperature, but most years share a similar overall trend. At the bottom of the pond, temperature trajectories vary quite a bit from year to year, and in some years, the lake bottom warms considerably. Abrupt changes in bottom temperature are usually the result of a wind-driven mixing event that brings surface water downward.
While regional air temperatures are broadly warming, it is important to note that the behavior of mountain ponds like Tumbledown are more complex. Neither the surface nor bottom show a clear warming trend from 2008 – present. The variation in the data suggest that additional factors including water clarity, wind, and pond depth play critical roles in shaping the thermal patterns of each mountain pond.
Maine Mountain Ponds 