Decreasing Open Water

A Day in the Life at Chicopee Lake

Editor’s Note: Don Lane, Elachee Teaching Naturalist and retired environmental scientist will provide insight, each month throughout 2022, about different environs and species in, and around Chicopee Lake, located in Georgia’s Chicopee Woods Nature Preserve, in south Hall County.

Don Lane’s Journal Entry: May 2022
Pond/Lake Succession: Chicopee Lake through the Years

If you have visited the lake over the course of a few years, you may have noticed it is getting smaller. That is, the area of open water is decreasing. It is, and here is why.

Lakes and ponds (whether natural or man-made) go through a succession.  Succession is a natural process by which a pond/lake changes over time. 

As Walnut Creek flows in a generally southward direction, it picks up sediment. The water velocity in Walnut Creek is sufficiently fast enough to allow many of the sediment particles to ‘defy gravity,’ and not fall to the streambed. However, when the fast-flowing water of Walnut Creek encounters the still water of Chicopee Lake gravity takes over. The heavier-than-water sediment particles drop and begin to settle at the bottom of the lake. This is the mechanism that contributes to pond/lake succession. 

The accepted model of pond/lake succession is: Pond/Lake >> Marsh >> Dryland/Grasses >> Shrubs >> Forest.

How fast this happens is dependent on two things: the rate of sedimentation and human intervention. For instance, if there is a lot of land disturbance upstream and proper sedimentation controls are not used, then more sediment than normal can reach the lake. Thus, speeding succession.

Humans can extend the life of a pond or lake by dredging. Dredging removes the bottom sediments allowing for more water in the pond/lake. Dredging is expensive and comes with the big problem of what to do with the dredged material. Chicopee Lake was last dredged in September of 2007.

According to lakesonline.com, which appears to get its information from the National Inventory of Dams, the dam was constructed in 1973 with a stated purpose of flood control. The owner of the dam is listed as the Upper Chattahoochee Soil and Water Conservation District. The surface area of the lake (the area of open water) was to be 20 acres. The current area of open water is estimated to be 8 acres.

Without human intervention, Chicopee Lake will continue its successional journey to forest.  How long will this take?  There are many complex factors involved such as extremely dry or extremely wet seasons, land disturbance upstream, human intervention such as dredging, and others.  However, based on my analysis of sedimentation rates, Chicopee Lake could be dry land by 2047.

Google Earth can be a useful tool to understand how an area changes over time using satellite images. The following set of pictures depict Chicopee Lake from 1993 to 2021.
Figure 1:  1993 A full 20 years after the construction of the dam. I estimated the open water to be about 15 acres.  The blue outline could be the size of the lake before sediment accumulated eliminating the open water from this section. Coincidentally, the blue area is about 20 acres.
Figure 2:  1999 The yellow highlighted box shows Walnut Creek meandering through the area that may have once been submerged but has transitioned to land.  The circle denotes what may be the predecessor of the beaver pond discussed in the April 2022 blog.
Figure 3:  2000 No significant changes. The open water area is approximately 13 acres.
Figure 4:  2005 Small ‘islands’ have formed. Open water is about 11 acres.
Figure 5:  2006 No notable change from a year ago.
Figure 6: 2007 The ‘islands’ from the 2005 image have seemed to disappear. This could be because the image was taken during high water or the fact that the lake was dredged in September of this year.
Figure 7:  2008 The image appears to have been taken in the winter, so it shows the lake a full year after the dredging operation. The left arrow points to Walnut Creek while the right arrow points to what may be another channel that formed because of dredging.
Figure 8:  2009 No notable change.
Figure 9:  2010 Note the peninsula forming where Walnut Creek enters the lake.  Open water is estimated to be about 9 acres.
Figure 10:  2012 No notable change in two years.
Figure 11:  2013 The peninsula continues to develop.
Figure 12:  2014 More sediment entering the lake has contributed to peninsular formation.
Figure 13:  2015 Open water (blue outline) is at current size of about 8 acres.
Figure 14:  2016 The beaver pond appears abandoned. Peninsula continues to develop.
Figure 15:  2017 No apparent change from last year.
Figure 16:  2019 Vegetation appearing on the peninsula.  This indicates the deposited soil is stable enough for plants to take root.
Figure 17:  2020 The peninsula continues to grow and migrate towards the dam.  Vegetation is now firmly established.
Figure 18: 2021 The peninsula continues to develop and migrate towards the dam and may eventually bisect the pond.