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Redfish Lake, Sawtooth Mountains, Idaho
Redfish Lake, located in the Sawtooth Mountains of Idaho (USA) is a popular recreation destination. The lake has very low productivity, and hence clear water: a 20-cm white Secchi disk can frequently be seen to a depth of 12-15 m (39-49 feet). A few endangered sockeye salmon spawn in the lake each year and the juveniles rear there for 1-2 years. The aid in their recovery, the lake is fertilized in some years to increase plankton growth, and hence the growth of the salmon that feed on these organisms.