Although thirteen species of fish were native to the lake, only the Utah sucker and the critically endangered June sucker remain. The dominant species in the lake is the common carp, introduced in 1883 as an alternative to the overharvested native fish. The carp is now estimated at 90% of the biomass of the lake and is contributing to a decline in native fish populations by severely altering the ecosystem. Pollution has also caused problems with the lake's ecosystem. Raw sewage was dumped into the lake as late as 1967. Pollution problems still remain; the lake's phosphorus and mineral salt levels are in violation of the Clean Water Act. In recent years, the lake has been prone to harmful algal blooms or HABs.