OWL WATER SAMPLING DATA ANALYSIS REPORT 2007

INTRODUCTION

Lake water quality samples were collected from June 20th through August 29th on a staggered time basis prompted by budgetary constraints at the testing laboratory. Twenty volunteers collected twenty-five samples 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. Again this year the City of Auburn did not collect samples at their sites so that data is unavailable. Since the samples were not collected each week, the charts showing trends are spotty with few points connected. The rainfall data is contiguous so that a line is plotted on the charts for it.

SUMMARY

The overall conclusion reached from an analysis of the data is that the bacterial water quality of Owasco Lake remains good. 2007 was a year with some wet periods and some dry periods Most of the lake sites gave low fecal Coliform numbers throughout the testing with <10 frequently determined. Surprisingly, the high rainfalls during the July 18th and 25th weeks did not appreciably change the fecal Coliform numbers excerpt at Rounds Lane and to a lesser extent Long Hill Road on the Inlet. No plausible explanation could be found for these observations. Turbidity data start high and then decline and remain fairly low for the rest of the sampling period. The high rainfall in mid to late July had little effect on the turbidity which defied explanation. Water temperatures in 2007 showed the normal trend with the values slowly rising to late July to early August and then declining in late August. The air temperature data followed a similar curve. Both data sets showed a drop in late July when high rainfall was recorded over a two week period and then the temperatures returned to the normal curve. This year there appeared to be algae showing up earlier and much more broadly distributed. The first week 9 sites reported algae and by mid-July 16 of the sites were reporting algae. Brown was dominant followed closely by Green. Some blue-green was also noted. Decreasing the sampling frequency has definitely limited the conclusions that can be drawn from the data set. Subtle but important changes and trends may have been missed because of the gaps in the data. It is hoped that it will be possible to return to weekly sampling in 2008.

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. The samples were collected on June 20th and 29th, July 11th and 25th, and August 8th, 22nd, and 29th. The fecal Coliform data shows high values on June 20th at a number of sites and then low numbers on the 29th. Reviewing the rainfall data for the entire month of June showed that there was no rain from June 8 until June 19th when 0.75 inches of rain were recorded. That deluge purged the lands and streams quickly which resulted in the high values recorded. The remainder of the sampling period produced low fecal Coliform numbers at most of the lake sites with many readings being <10. Surprisingly, the high rainfalls during the July 18th and 25th weeks did not appreciably change the fecal Coliform numbers excerpt at Rounds Lane and to a lesser extent Long Hill Road on the Inlet. No plausible explanation could be found for these observations.

The turbidity data are recorded in Data Sheet 2 and the plots are shown in charts 3 and 4. The turbidity starts high at a number of sites on June 20th and then remains low until August 22nd when it again jumps up somewhat. It does not respond very much to the high rainfalls near the end of July. I am again at a loss to explain this behavior.

The water temperature data shows a much better correlation to the rainfall data than the Coliform or turbidity data did. The data is shown in Data Sheet 3 and Charts 5 and 6. Even though the data is spotty, it is clear that the temperature generally rose from late June through July to early August and then declined in late August. The heavy rainfalls the weeks of July 18th and 25th resulted in a noticeable drop in the water temperatures recorded on July 25th but then the temperatures had recovered by August 8th. A high temperature of 30 C. was recorded at two sites on that date. The air temperature data are shown in Data Sheet 4 and Charts 7 and 8 and they show exactly the same trends as the water temperature data. The same drop on July 25th from the rainfall was seen with the air temperature data. As has been noted in previous reports, the air temperature data shows more variability than the water temperature data due to the variation in when the data is recorded with many samplers recording at 6:00 AM while some are after 10:00 AM. Also, the air temperature reacts much more quickly to a change in weather patterns.

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 9 sites reported algae and by mid-July 16 of the sites were reporting algae. The predominant color was Brown followed closely by Green. Some blue-green was also seen.

In closing it is noted that the abbreviated sampling schedule used this season has definitely impacted the overall value and integrity of the data and has made the interpretation much more difficult. It is hoped that the sampling will be able to be put back on a weekly schedule in 2008 and that the sampling will commence earlier in June.

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

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