1. Cyanobacteria Blooms in Upper Klamath Lake
Lauren Senkyr
ESR 575 Limnology
November 23, 2009

2. Upper Klamath Lake Oregon’s largest lake Oregon’s largest lake:
Volume ~ 536 x 1036
Surface area ~275 km2
Shallow, hypereutrophic
Avg. depth 2.2 m
Mean depth 2 m
Max. depth 15.2 m

3. Management issues Water diversions ESA listed suckers
Agriculture- nutrient inputs + water use
Dams along Klamath River

4. Cycle of Water Quality Degradation in Upper Klamath Lake
↑ Algal Blooms
↑ Phosphorus
↑ pH
↑ Nutrient Loading
↑ Unionized Ammonia
Fish Die-offs
↓ Dissolved Oxygen
↓ Algal Blooms

5. Cyanobacteria Aphanizomenon flos-aquae dominant June-October
“Blue green algae”
Aphanizomenon flos-aquae
dominant June-October
1st appearance 1933
Collapse causes anoxic conditions that lead to fish kills
Commercially harvested
1 toxic species in UKL (Microcystis aeruginosa)

6. Basic Biology of AFA
Does not grow in pH < 7.1, water temperature < 11 degrees C
Yamamoto and Nakahara, Limnology (2005)

7. Current Conditions in Upper Klamath Lake Favor AFA
High pH
High water temperatures
Eilers et. al. 2004

8. Internal P Loading Internal load ~2/3 Total P in Upper Klamath Lake
Decrease in total P in top
2 cm of sediment before/
after bloom
(Simon et. al. 2009)

9. The Role of Wind
Very strong relationship between climate and water quality in Upper Klamath Lake
↑ wind speeds = ↓ water column stability
Wind induced mixing of
sediments= increased
nutrient availability
(Kann and Welch 2005)

10. Impacts of altered hydrology
Sedimentation
Nutrient retention
Greater internal loading
Wind control accentuated by lower water levels
Eilers. Et. al. 2004

11. Implications for wetland restoration and dam removal?