Recent studies in Thai reservoirs have found blooms of toxin-producing algae in the
water bodies (Peerapornpisal, 2006). Earlier studies in the Mae Kuang Udomtara Dam
reservoir in Chiang Mai found proliferation of the blue-green algae Microcystis
aeruginosa, which secretes the potent liver toxin microcystin. The explosive growth
of this alga is related to nutrient enrichment, particularly phosphates (Peerapornpisal
et al 1999). In 2001 and 2002 the toxic blue-green algae Microcystis aeruginosa was
found in every sample taken in Mae Kuang Udomtara reservoir in Chiang Mai,
although at lower concentration than the indicative of a harmful bloom (Chanttara et
al 2002).