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2019 Pre-Season Water Sampling
Posted on Apr 17th, 2019
Mike Bergin and I took our first 2019 pre-season water samples on Friday, 4/12/2019 Between 9:16 am and 9:31am , during a light rain.
#1 Dock 13 cfu
Lake water temperature was 67-68F/19.4-20C at the time of the sampling. The SECCI clarity reading was 30 inches. The afternoon before the sampling, the lake water near the shore was 71F. Two weeks before this sampling, the lake water was 53.6F (12C), a week prior to the test, the lake water was 62F (16.7C), The SECCI readings have been consistently around 29-32 inches.
At this time of year, the lake water can warm quickly enough for comfortable wading or shallow swimming on a warm sunny afternoon.
Our protocol discourages sampling immediately after any significant rainfall because the results can be influenced by the volume of runoff (diluted) and any surface contamination that may have been flushed off of the ground in the upstream watershed (concentrated). So results taken after a rainfall are less accurate, and less representative of the overall condition of the water in the lake.
The day before the sampling, there were very noticeable bands of yellow-green pollen visible all over the lake surface, and a moderate concentration of two or three species of large waterfowl including Canada Geese, and Cranes. There were also several types of smaller birds on the shore and in the lake. The rain had just started about 10-15 minutes before we took the first sample, and it was pushing the visible bands of floating pollen back towards the retaining walls that border most of the lake.
The lake level was high at the time of sampling, about 1 inch was flowing over the full width of the top of the spillway. The weekend rainfall produced enough water to replace the entire volume of the lake, although the hydro-dynamics of water flow probably did not result in all of the lake water getting displaced. I got 3.85 inches of water in my backyard rain gauge during that time. I am near the North boundary of the watershed. After we completed the last lake restoration excavation in 2003, we were told that a hard rain of about 2.5 inches on partly saturated ground would refill the lake. This was not a particularly accurate estimate; it wound up taking between 3.5 inches and 4 inches of rain over a three week period to fully refill the lake back up to the lowest step in the spillway. The recent rainfall produced the same amount of water in 2.5 days.
Last fall’s fish bounty brought several new species of birds to Eastwood Lake. Some of those birds are still foraging there now. It will be interesting to see how many, if any, of these new visitors become permanent residents. Over the years, our man-made lake has developed its own evolving ecosystem. In the 1970s and early 1980s, the area where the Booker Creek forebay now occupies a space in the middle of a wooded wetland, there was a meadow with a baseball field, bordered along the creek by Bradford Pear trees. Between that and the West end of the lake was a fairly thin wooded border. That area became the present wetlands, mostly due to the efforts of some imported beavers. During that same period of time, flocks of migratory Canada Geese became year round residents.
This is a good time for our seasonal reminder about using “lake margin” fertilizer along the shore areas, and along our tributary creeks. Make sure to “water it in” so it does not get flushed into the lake. Do not fertilize before any expected rain. Fertilizer of any sort, in the lake, contributes “nutrients” to an annual algae cycle that can get out of hand under the right weather conditions. An annual algae bloom is usually not dangerous to the health of the lake, and it is not particularly “abnormal”, but can make the water unpleasant, and if there is enough of it, it can stain swimwear and irritate skin.