In 2005, the Carpenteria Valley Water District in Carpinteria, California, raised water quality concerns when "leopard spots" approximately 5 to 10 cm. in diameter appeared on the water surface under a newly constructed aluminum reservoir cover.
While the floating material was not toxic, it was recommended that movement of the water surface be induced so that quiescent conditions would be avoided which would eliminate the primary condition for calcite raft formation [REF].