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Lakes Alive

Lakes Alive

Jerry Weiland and I started monitoring Lake Kegonsa and Lake Mendota. Each week he collects samples and I test water parameters. The lakes are known to go through seasonal transformations including the bothersome algae blooms. We aim to correlate data, with plant and algae performance. What analogies can we draw between "big" aquatic ecosystems and small ones of the home aquarium?

Here is an example of a weekly report. Though we won't present specific profiles every week, we'll share our observations periodically and venture some analysis.

L. Kegonsa 5/8/03

PH 7.98
N = 1.2 ppm, down from 7.04 ppm 5/2/03
Fe = 0.03 ppm, same
P = 1.25 ppm, up from GH 14 = 250.6 ppm, down from GH16 = 286.4 ppm
KH 11.5 = 205.85 ppm, down from KH 13 = 232.7 ppm
Conductivity = 247.5 ppm TDS(Total Dissolved Solids), down from 265 ppm

L. Mendota 5/8/03

PH 7.89
N = 4.4 ppm, down from 12.32 ppm
Fe = 0.03 ppm, down from 0.17 ppm
P = 0.25 ppm, slightly up from 0 ppm
GH 12 = 214.8 ppm, same
KH 11.5 = 205.85 ppm, up from KH 10 = 179 ppm
Cond. = 197.5 ppm TDS, ~ same

Comments:

Lake Kegonsa water was slightly yellow and contained debris suspensions. One suspects disruptive effects of rain squalls on a shallow lake would account for this, to a degree. Nitrogen was reduced a lot and P increased a lot. GH & KH went down and conductivity went down a small amount, probably because of recent rains.

The previous ratio of P to N was good (P 0.5 to N 7.04). 5/8/03 reading of (P 1.25 to N 1.2) isn’t a good sign. As phosphate increases, expect to see the algae season begin. Source of increasing phosphate? One suspects runoff from agricultural lands, and leaking septic systems.

With warmer temperatures and increase of daylight, aquatic plants grow swiftly. This may account for the reduction of nitrogen in both lakes.

Mendota is a larger and deeper lake. The water sample was very clean. Nitrogen was reduced and Fe, very much so. Phosphate showed a modest increase.

So, which lake will make a blooming algae mess first?