Land-use change and increased development are the primary factors causing water quality and habitat degradation in Lake George and its watershed.  As the intensity of development and use of lake and watershed increases these impacts are ultimately measured in the lake.  Development pressures manifest themselves in the levels of these water quality factors.  Increased nutrient loading from development results in the expansion of habitats for invasive plants and animals.  Additionally, increased algal growth and consequent decrease in water quality and dissolved oxygen occurs.

Lakes are divided into three trophic categories: oligotrophic, mesotrophic, and eutrophic.  An oligotrophic lake is typically a large deep lake with crystal clear waters and a rocky or sandy shoreline.  Both planktonic and rooted plant growth are sparse, and the lake can support a coldwater fishery.  A eutrophic lake, on the other hand, is typically shallow with a soft, mucky bottom.  Rooted plant growth is abundant along the shores and out into the lake, and algal blooms are not unusual.  Water clarity is not good and the water often has a tea color.  If deep enough to thermally stratify, the bottom waters are devoid of oxygen. Mesotrophic is an intermediate trophic state with characteristics between the other two.

Lake George has historically been categorized as oligotrophic.  However, water quality monitoring data collected by the Darrin Fresh Water Institute has shown a recent trend towards mesotrophic.  This is a result of increased nutrients entering the waterbody from the surrounding watershed.

 Results from the water quality monitoring project using remotely-sensed data appear to support this assessment.  Chlorophyll data was used from the processed TM imagery from August 1993 and August of 2002 to calculate TSI based on Carlson’s TSI formula (TSI-C = 30.6 + 9.81 x ln(chl) < Chl in mg/m^3).  While results for the entire lake were comparable, 37.4 and 37.5 for respective years, there were shifts in the histogram values for the 2002 data indicating a larger number of pixels with high chlorophyll concentrations.  In 2002, 16,496 pixels were mapped as having the highest chlorophyll ranges compared to 7,913 pixels in 1993.  Repetitive, long-term monitoring of the waterbody using remotely-sensed data will give an accurate overview of eutrophication trends within the lake.

 Other parameters measured for this project such as colored dissolved organic carbon and suspended minerals were found to be in a normal range.  Values for colored dissolved organic carbon were low throughout the lake.  Suspended mineral values were also very low, but there were localized areas surrounding developed areas where it appears these land-uses are increasing sediment loading. Further study would be necessary to determine this causal relationship.