Back to High Normal

Lake Testing in 2009

In terms of human organisms – especially when a lot of them are analyzed and compared over a number of years – scientists speak in terms of natural variability to account for occasional wild swings in data. We all know someone who healthwise did everything wrong – smoked incessantly, drank too much, ate horrible food – yet lived to be 90. We also know someone who did everything right: ate wisely, didn’t drink alcohol, got lots of sleep and exercise – but died early of a heart attack.

That’s because there are multitudes of variables with regard to organisms. This is especially true of an organism as large and complex as a lake. In recent years, we have experienced some wild swings. In summer 2008, our Seechi disk readings – the device by which we measure clarity – were off the charts. We averaged almost 20 feet when the average over almost three decades has been a bit over 11 feet. At one point, you could see down, by official measurement, 36 feet.

Conversely, we had a bad summer in 2005. On the day after the Fourth of July, the Seechi disk reading was 3 feet. The average was 8.6 feet. Lots of pond scum accumulated, presumably because of the influx of zebra mussels.

But it seems that in terms of lake readings last summer, we are back to normal, whatever normal means. Our transparency average in 2009 was 14 feet, somewhat above the overall 20-year average of 12.0 feet. Our spring phosphorous reading was so low that the DEQ rated it as “a value less than the method detection limit.” In the fall, when water stratifies in terms of heat and bacterial growth, the reading was still a relatively low 8 parts per billion.

The same applies with chlorophyll testing. Five readings produced an average of 1.9 parts per billion. Our Carlson Trophic Index score was 37 which puts us (barely) into the oligotrophic category. That’s good.

2009 at a glance

A more exhaustive discussion (more information than you want to know) can be found in the updated Lake Testing Report.