 Currently the largest freshwater marsh in Orange County, the San Joaquin was once severely polluted and degraded, having being used first as the Newport salt works and then as farmland.During the 1950s and 1960s, San Diego Creek followed a much shorter, channelized course to the bay, bypassing the marsh entirely.In 1972 the Irvine Company leased the marsh to hunting clubs, which restored the creek's original, longer course to the bay and built levees to create duck ponds.