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Effects of Drought on Lake Almanor Water Quality
Dr. Gina Johnston and Mr. John McMurtry
California State University, ChicoOctober 21, 2014
Effects of Drought on Lake Almanor Water Quality
Three Major Effects Have been Observed since 2009: • Increase in abundance of algae, especially blue-green algae
(cyanobacteria)
• Increase in temperature of the surface water (epilimnion) in the summer
• Decrease in dissolved oxygen in the summer throughout
the water column
Blue-green algae (Cyanobacteria)Blue-green algae (Cyanobacteria) are very small, structurally simple plants that occur naturally in aquatic environments. Some can produce toxins potentially harmful to humans and other animals.
When conditions are right, algae can reproduce rapidly in what is known as an algal bloom. Blooms can cause visible surface scum to form, produce noticeable tastes and smells, and harm other aquatic life. A cyanobacterial bloom is especially dangerous due to the possible toxins produced by many species.
Conditions that increase the chances of an algal bloom:• Little water movement, in terms of both horizontal flow and vertical mixing• High levels of nutrients – phosphorus and nitrogen• Warmer water temperatures
Some B-G Genera Found in Lake Almanor: Lyngbya
Some B-G Genera Found in Lake Almanor: Anabaena
When there are too many algae – a bloom
Algal Surface Scums and Odors
Lake Almanor Algal Populations 2009-2014
Summer Water Temperature and Dissolved Oxygen: 2009-2014
2009:Look at T and O in 8-12 meter range
0 2 4 6 8 10 12 14 16 18 20 22 240
2
4
6
8
10
12
14
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24
Temperature and Dissolved Oxygen at LA-01, July 7, 2009
Temp(ºC)
DO (ppm)
Degrees Celsius or Parts Per Million
Dep
th (
m)
Summer Water Temperature and Dissolved Oxygen: 2009-2014
2009:Look at T and O in 8-12 meter range
0 2 4 6 8 10 12 14 16 18 20 22 240
2
4
6
8
10
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22
24
Temperature and Dissolved Oxygen at LA-01, July 7, 2009
Temp(ºC)
Degrees Celsius or Parts Per Million
Dep
th (
m)
0 2 4 6 8 10 12 14 16 18 20 22 240
2
4
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24
Temperature and Dissolved Oxygen at LA-01, July 21, 2014
Temp(ºC)
Degrees Celsius or Parts Per Million
Dep
th (
m)
Summer Water Temperature and Dissolved Oxygen: 2009-2014
• 2014: Look at T and O in 8-12 meter range
0 2 4 6 8 10 12 14 16 18 20 22 240
2
4
6
8
10
12
14
16
18
20
22
24
Temperature and Dissolved Oxygen at LA-01, July 21, 2014
Temp(ºC)
DO (ppm)
Degrees Celsius or Parts Per Million
Dep
th (
m)
Environmental Requirements of Brown Trout
• Temperature: 5° C – 20° C (Best growth in cool water)
• Oxygen: greater than 5 ppm
(reduction in growth rate below 5 ppm)
Trout Habitat, July 2009, Lake Almanor
0 2 4 6 8 10 12 14 16 18 20 22 240
2
4
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Temperature and Dissolved Oxygen at LA-01, July 7, 2009
Temp(ºC)
DO (ppm)
Degrees Celsius or Parts Per Million
Dep
th (
m)
Trout Habitat, July 2014, Lake Almanor
0 2 4 6 8 10 12 14 16 18 20 22 240
2
4
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22
24
Temperature and Dissolved Oxygen at LA-01, July 21, 2014
Temp(ºC)
DO (ppm)
Degrees Celsius or Parts Per Million
Dep
th (
m)
Effects of Drought on Lake Almanor Water Quality
• Increase in algae, especially cyanobacteria, due to warmer water temperature
• Decrease in acceptable trout habitat in summer, due to warmer water temperature and lower dissolved oxygen
