Water quality from Magma Shading Trials

The purpose of the trial is to examine the effect of a 95% shade cloth cover over a canal. Our goal is to determine if this level of light reduction is capable of lowering the numbers of blue green algae in the canal. Our hypothesis is that by reducing the number of algae cells in the canal, we may also reduce the production of MIB and geosmin. These compounds impart unpleasent taste and odors to drinking water.


Photo of shade screen
Close-up photo of shade screen
Photo of shade screen and canal

Date Location Time pH Temp
(C)
DO
(mg/L)
TDS
(mg/L)
Nitrate
(mg/L)
Ortho-
Phosphate
(mg/L)
Total
Phosphate
(mg/L)
May 7, 98 Before Screen 12:40 NS 22.5 8.9 560 0.19 0.08 0.66
May 7, 98 End of Screen 12:50 NS 22.4 9.0 560 0.19 0.10 0.68
April 22, 98
Initial
Pre-screen
middle of site
12:00 NS NS NS NS 0.21 0.04 0.57


Algae counts for
April 22, 1998
Phytoplankton
(cells/ml)
Periphyton
(cells/ml)
Cyanophytes
Aphanotheca 4,333.33 241.18
Microcystis 18,000 553.37
Spirulina 666.367 none recorded
Lyngbya none recorded 62.22
Chlorophytes
Ankistrodesmus 1333.3 none recorded
Chlorella 3333.33 none recorded
Scenedesmus 4000 none recorded
Rhizoclonium none recorded 116.65
Schroederia none recorded 139.86
Ulothrix none recorded 209.79
Chrysophytes
Amphipleura 666.67 none recorded
Cocconeis 2000 489.51
Cymbella 2666.67 273.25
Fragilaria 1333.33 318.65
Gomphonema 666.67 88.35
Navicula 3333.33 227.86
Diatoma none recorded 46.62
Synedra 3333.33 167.49
Tabellaria 666.67 none recorded
Gyrosigma none recorded 55.89
Melosira none recorded 122.73
Cyanophytes
Aphanothece 4333.33 241.18
Microcystis 18,000 553.37
Spirulina 666.367 none recorded
Lyngbya none recorded 62.22