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great sacandaga lakeDFWI Research:

Great Sacandaga Lake


Executive Summary

In 2009, the Great Sacandaga Lake Assessment Program focused on bacterial water quality as an indicator of the suitability of the lake waters for contact recreation (i.e. swimming and wading) and invasive species as a result of the introduction of an invasive crustacean zooplankter, the Spiny waterflea.  Results of these two components of the assessment program for the basis of the current report.

The Great Sacandaga Lake Coliform Monitoring Program (GSLCMP) collected water samples from suspected contamination sources and heavily used recreational venues throughout the lake basin.  The purpose of these collections was to locate possible sources of bacterial contamination to Great Sacandaga Lake and provide the information, in a timely fashion, to local and state regulatory agencies for remedial action.  Twelve to 15 shoreline locations were sampled during each samplingcycle.  Sample collection occurred monthly in July and August.  The time interval coincides with the period of maximum population density and intensity of recreational use.  Two primary measurements were made for each sample: Total Coliform (TC) and Fecal Coliform (FC) Bacteria.  These bacteria serve as indicators of the presence of animal or human waste.  Thepresence of elevated levels of these bacteria indicates potentially disease-causing protozoans, bacteria and other microorganisms may be present in the water. 

Interim reports on the bacterial testing programs were released approximately monthly throughout the sampling season.  Results from the current study indicate that bacterial levels in Great Sacandaga Lake are more than adequate for all intended uses.  Elevated bacterial levels, however, were observed in 2009 in Kennyetto Creek at its’ intersection with NYS Route 30.  While none of the 2009 bacterial samples from Kennyetto Creek exceeded single sample standards set by the NYS Dept. of Health standards for swimming or wading, all samples exceeded the 5 sample average limits.  Follow-up investigations along Kennyetto Creek are warranted to determine the source or sources for the bacteria.  In 2008, a NYS DEC investigation concluded that no single source was responsible, but a diffuse group of non-human sources were likely.  Overall, bacterial results indicated exceptionally high water quality throughout Great Sacandaga Lake.

In the Fall of 2008, the Spiny waterflea, (Bythotrephes cederstroemi) an invasive member of the zooplankton community was first reported in Great Sacandaga Lake.  This small crustacean invaded the Great Lakes in the mid 1980’s, where it competes with native zooplankton for available resources.  Zooplankton are the base of numerous food webs, including those which control the growth and abundance of gamefish such as trout, perch and walleyed pike.  While the effect the Spiny waterflea are having on the ecosystems of the Great Lakes region is uncertain, these crustaceans compete directly with young perch and other small fish for food, such as native zooplankton.  Fishermen are already having problems with this animal clogging reels and rod guides.  Spiny water fleas also reproduce rapidly. During warm summer conditions each female can produce up to 10 offspring every two weeks.  As temperatures drop in the fall, eggs are produced that canlie dormant all winter, but are ready to hatch in the Spring. 

Spiny waterflea were encountered throughout Great Sacandaga Lake in 2009. These invasive zooplankton were present in small numbers at most locations, with the outlet area near Conklingville Dam producing the fewest.  The majority of specimens were found in deeper waters from 6 to 8 meters depth in July and 8 to 10 meters depth in August.  The distribution of spiny waterflea appears to be limited by lack of dissolved oxygen in the deeper waters of the lake, where less than 2 ppm dissolved oxygen is present from August thru September at depths greater than 12 meters.  Native zooplankton abundance, biomass and average size were substantially lower in 2009 when compared to results from 2003 and 2004.  While the sample size is very limited to reach conclusions, this decline may be attributed to theinvasion of Great Sacandaga Lake by the Spiny waterflea, a species known to prey on other zooplankton.  Perhaps the most encouraging result of the zooplankton survey was the extremely limited numbers of Spiny waterflea reported at the Conklingville Dam or outlet site.  Lack of large numbers of this invasive species in the outlet area may signal limited release of this species to other waterbodies.  The ultimate impact of the spiny waterflea on native populations will only be confirmed by future assessments. 

 

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