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OWL WATER SAMPLING DATA ANALYSIS REPORT |
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OWL WATER SAMPLING DATA ANALYSIS REPORT |
INTRODUCTION
During 2008 water samples were collected from 28 sites by 20 volunteers around the lake from June 18th through August 27th. The sampling volunteers were assisted by James Soucy, an AmeriCorps volunteer, who picked up the samples around the lake each week as well as took the samples for the four City of Auburn sites. James transported the samples to the laboratory at the Auburn Sewage Treatment Plant and also did the actual testing of the samples for coliform and turbidity under Andy Roche's supervision. The sampling volunteers also measured air and water temperatures and noted wind direction and relative strength. They recorded the sky condition, algae citings, and also reported any unusual observations during the week. All of the information was entered in a computer spreadsheet for later analysis. Rainfall data was provided by Anthony DeCaro from the Auburn Weather Monitoring Station at the Water Filter Plant on Swift Street. The daily data was converted into weekly totals and entered into the database after the sampling season was done.
SUMMARY
The overall conclusion reached from an analysis of the data is that the bacterial water quality of Owasco Lake remains good. The summer of 2008 was another wet year which may be the reason that the fecal Coliform numbers are lower generally than previous years. The weed growth also was not as vigorous this year with the exception of the curly-leafed pond weed that peaked in the late spring displaying areas near the shore that looked brown in color. The Eurasian milfoil was not as prevalent this year as in past years. Algae were noted in a number of areas this year with the blue-green and brown predominating. Generally, if algae were seen at a particular site in June, they were present for the rest of the samplings. Water temperatures seemed to track the rainfall data with a 1 week shift frequently displayed. Even with all the rain recorded this year, the water temperature reached 28 degrees Centigrade on July 16th. Three sites reported that temperature on July 16th. The high temperatures seem to be at odds with the amount of rainfall but it was suggested that the rains came in short, heavy bursts generally followed by clear, sunny periods.
DETAILED ANALYSIS
As had been done in 2004, selected sites were plotted comparing fecal Coliform and weekly rainfall over the course of the collection period. The actual data is attached as Data Sheet 1 and the plots are presented as Charts 1, 2, and 3. The first thing that is revealed is that this past summer had a lot of rain with most weeks recording an inch or more of rain. Conversely, the fecal Coliform numbers generally were less than in previous years with only occasional numbers TNTC (too numerous to count) signified by a value of 5000 on the spreadsheet. Many sites routinely provided a fecal coliform number <10 which was entered on the spreadsheet as 1. From a fecal Coliform standpoint, 2008 was a very good year for the lake. The swimming beach at Emerson Park also provided low numbers. Chart 3 compares the West and East sides of the swimming beach. As was reported in 2004, the East side of the designated area has higher fecal Coliform numbers than the West side. You may recall that in 2004 Gary Duckett (Cayuga County Director of Parks and Trails) found that during heavy rain events that the area behind the Agricultural Museum flooded and large quantities of water were dumped into the Lake just east of the swimming area by two large drainage pipes running under Route 38A. The water discharging from the pipes routinely read high in fecal Coliform which directly affected the readings taken from the shore on the east side of the swimming area. Again in 2008 the data shows a higher fecal Coliform number for the East compared to the West side but the actual numbers are much lower that they were in 2004. The swimming area was not closed at all in 2008.
The turbidity data are presented in Data Sheet 2 and selected sites are shown graphically in Charts 4, 5, and 6. The turbidity seems to follow the rainfall data more closely than the fecal Coliform data did although it appears to lag behind the rainfall by a week.. The fact that the turbidity follows the rainfall trend is not surprising since higher rainfall amounts would tend to cause more erosion and thus result in higher suspended solids in the run-off. The higher numbers seen for the East side of the swimming beach compared to the West side (Chart 6) are another indicator of the strong influence that the pipes under Route 38A are causing on the east side of the swimming area. The water clarity continues to be high probably largely due to the action of the Zebra mussels. Surprisingly, this year the weed growth did not appear to be as prolific as in the past few years. However, in the late spring there was an explosion of curly-leafed pond weed around the lake such that there appeared to be "brown scum" on the surface of the water. The "brown scum" was actually the tops of the curly-leafed pond weed as it reached the surface of the lake. The weed soon died off and the weed level from then on was lower than in past years. This may be related to the lower water temperatures. The emergence of Eurasian milfoil seemed to be several weeks later this year. Again, the variability of the results from observations on the Lake demonstrate how inter-related all of the factors are with climate and weather and what a truly complex entity the Lake is.
A number of test sites reported algae in June. Generally, if algae were noted in June at a site, that site would report algae on each subsequent sampling. Blue-green and brown were the predominant species. The coverage of the algae at any given site seemed to remain relatively constant throughout the sampling based on the way the comments were recorded. Some additional sites began reporting algae as the testing season progressed while some sites remained free of algae throughout the year. Again, once algae were reported at a site, that site reported algae on each subsequent sampling.
The water temperature data referred to above is presented in Data Sheet 3 and selected sites are shown graphically in Charts 7 and 8. The maximum temperature recorded occurred on July 16th at 28 degrees Centigrade (82 F.) and was noted at three test sites. In 2004 the maximum temperature was 25 degrees Centigrade and it occurred on August 4th. It was noted in the 2004 report that that year was also a rainy year and the temperatures of the water were somewhat lower than other years when the weather was much drier. I believe that the rain came down heavily when it did rain in 2008 and that was followed by clearing and sun. That may explain the higher temperature trends in 2008 versus 2004. In any case, it is clear from the charts that the water temperature is unrelated to rainfall amount.
For comparison purposes, the air temperatures were also evaluated over the course of the sampling. The data is shown in Data Sheet 4 and the same sites plotted for water temperatures were plotted for air temperature. These are shown in Charts 9 and 10. The trends are very similar although the actual temperature values are different. One trend that emerged was the cool mornings recorded throughout August; values as low as 50 degrees Fahrenheit (10 degrees Centigrade) were frequently recorded. As with the water temperature results, the air temperature data was unrelated to the rainfall amount.
ACKNOWLEDGEMENTS AND RECOGNITION
Each year OWL hopes that it can learn a little more about the complex factors that are impacting Owasco Lake while at the same time realizing that there are inherent year-to-year variations superimposed on these study parameters. The invaluable assistance of the OWL Water Quality Monitors allows OWL to produce a vast amount of data to be studied and evaluated in an attempt to better understand our watershed. Only with the continued dedicated efforts of this special class of volunteers can OWL hope to achieve the level of knowledge and understanding that is sought. The additional assistance from Cayuga County Soil and Water and the Auburn Water Filtration Plant providing James Soucy (AmeriCorps volunteer) to do the sample pick-ups and testing is appreciated. Andy Roche's invaluable assistance with supervising the testing at the Sewage Treatment Plant in Auburn is also gratefully acknowledged. On behalf of the OWL Board, I want to personally thank the OWL volunteers for all of their fine efforts and to assure them that their contributions are deeply appreciated.
Submitted by:
Dick Coalson
Water Testing Group,
Environmental Committee