"Microcystis aeruginosa Occurrence in the Klamath River System of Southern Oregon and Northern California"


Toxic blooms of the cyanobacteria Microcystis aeruginosa (MSAE) were documented in Copco and Irongate Reservoirs (the lowermost projects of PacifiCorp’s Klamath Hydropower Project-- KHP) in 2004 and 2005 (Kann 2005). The first documented toxic bloom occurred in Copco Reservoir on September 29th 2004 when 1.9 million cells/ml of MSAE were associated with a microcystin toxin concentration of 482 μg/L. Microcystin is a potent hepatotoxin capable of causing chronic liver damage and acting as a tumor promoter (Carmichael 1995; Chorus et al. 1999; Chorus 2001). Copco and Iron Gate Reservoir data clearly showed the occurrence of large and widespread blooms of MSAE and microcystin toxin levels in 2005 (Kann 2005: shown here in Fig 1). During the July-September period, cell density and toxin levels exceeded the World Health Organization (WHO) Moderate Probability of Adverse Health Effect Level (MPAHEL) often by 10-100’s of times; likewise, the Tolerable Daily Intake (TDI—see Kann [2005] for description) was also commonly exceeded by more than 10-100 times throughout the July- September period.


Water-quality impacts of wetland management in the lower Klamath national wildlife refuge, Oregon and California, USA

Extrait :

"Insufficient water supply and poor water quality are major problems in the Klamath Basin of southern Oregon and northern California, USA. Various land-management practices and competing demands for water in much of the basin have led to degraded environmental conditions and poor water quality (excessive nutrients, warm temperatures, high pH, low dissolved oxygen).


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