Unusually low dissolved oxygen killed fish in the ocean adjacent to the Hobe Sound National Wildlife Refuge. The low oxygen levels could be related to recent nutrient-rich freshwater discharges from Lake Okeechobee. Almost 1.5 million dead fish were found dead in the C-24 Canal in late June after heavy rains caused an increase in polluted runoff which lowered the amount of dissolved oxygen in the waterway. There were no further sightings of dead fish in the ocean after the freshwater discharges into the St. Lucie stopped.