OWL WATER SAMPLING DATA ANALYSIS REPORT 2006
INTRODUCTION
Lake water quality samples were collected from June 21st through August 30th. Twenty volunteers collected twenty-five samples weekly for testing at the City of Auburn Waste Treatment Plant for Coliform and turbidity under Andy Roche's supervision. The volunteers also measured air and water temperatures and noted wind direction and relative strength. They recorded the sky condition, algae observations, 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 Tony 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 in the fall. This year the City of Auburn did not collect samples at their sites so that data is unavailable.
SUMMARY
The overall conclusion reached from an analysis of the data is that the bacterial water quality of Owasco Lake remains good. 2006 was another very wet year with most weeks recording 0.5 inches of rain or more throughout the testing period. Most of the lake sites gave low fecal Coliform numbers throughout the testing with <10 frequently determined. (<10 is set to 1 in the Data Sheet for graphical purposes; values of TNTC were set to 5000 again for graphical purposes.) The two Inlet sites, Dutch Hollow, and Sucker Brook seemed to lag a week behind the rainfall trends which may be related to the large area these streams drain and the amount of time it takes for the water to reach the sampling point after the rainfall. Turbidity data closely follow the rainfall curve with the exception of Sucker Brook, Dutch Hollow, and the two Inlet sites which lag about a week behind. Water temperatures in 2006 were a little lower than in 2005 with similar trends through the sampling season. Algae observations showed that their activity was present by the 21st of June at several sites and rose in incidence through July peaking in late July to early August before starting to slowly decline near the end of August. The distribution was heavier than in 2005 and the predominant color was Brown followed closely by Green. Some blue-green was also recorded.
DETAILED ANALYSIS
As had been done last year, 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 and 2. As was noted in 2005, the 2006 testing season was also wet with most weeks showing at least a half inch of rain and with a few weeks exceeding 1.5" to as much as 3.7". The fecal Coliform numbers showed some mild correlation with the rainfall with higher numbers occurring with higher rainfall amounts. The two Inlet sites and Dutch Hollow seemed to lag about a week behind the rainfall peaks with their fecal Coliform peaks. This may be related to the long length of their streams and the amount of time it takes to get the water to the sampling points after the rainfall event.
The turbidity data was also compared to the rainfall information and is presented in Data Sheet 2 and in Charts 3 through 6. The conclusions expressed above about the fecal Coliform data seem to be mirrored with the turbidity results. The two Inlet sites and Dutch Hollow again seem to lag by a week whereas the other sites seem to closely follow the rainfall data. Because the Inlet site numbers peaks were much higher than the other sites, these two sites were removed from the selected data sets and all the remaining selected sites were plotted in Charts 5 and 6 to more clearly depict the actual changes. A review of the data in these Charts reveals that a number of the sites do closely follow the rainfall trend but Dutch Hollow and Sucker Brook seem to lag by a week. As I hypothesized above, the long length and slow water movement to the sampling site may account for this lag. Also, it must be remembered that the rainfall data is summed for each week and does not discriminate between rain early in the week or at the end. This could also impact on the trend shift one way or the other over the course of the summer.
The water temperature data are presented in Data Sheet 3 and selected sites are shown graphically in Charts 7 and 8. The water temperature slowly rose to a peak at the beginning of August and then it began to decline. The highest temperature recorded was 31 C. (88 F.) at Sucker Brook on August 2nd. There is a slight tendency for the water temperature to slow it's rate of rise due to heavy rain and then resume the rate when the rainfall is less.
The air temperature at each site was also compared to the rainfall. The data is shown in Data Sheet 4 and selected sites are shown in Charts 9 and 10. The trends of the air temperatures are similar to the water temperatures although the data seem to jump around a bit more. It also seems to be more responsive to rainfall that the water temperature was. The time that the air temperature was taken also has a noticeable affect on the result. Many readings were taken at 6:00 AM while some of the data was not recorded until 10:00 AM or later when the sun was much higher in the sky.
Algae observations were again recorded by the volunteers during their samplings and are shown in Data Sheet 5. This year there appeared to be algae showing up earlier and much more broadly distributed. The first week 12 sites reported algae and by mid-July most of the sites were reporting algae. The predominant color was Brown followed closely by Green. Some blue-green was also seen.
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.
Joe Wasileski was the water testing program coordinator and made all the preliminary arrangements and contacts. In addition he made sure that all the samplers were on board and stocked with bottles and data sheets. He also made sure that the samples were picked up promptly and delivered to the testing facility. Andy Roche's invaluable assistance with supervising the testing at the Sewage Treatment Plant in Auburn is gratefully acknowledged. Anthony DeCaro's provision of the rainfall data from the Auburn weather monitoring site at the Swift Street Water Filter Plant 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