Eutrophication

Eutrophication is the long-term over-enrichment of a water body with dissolved nutrients — primarily phosphorus and nitrogen — from runoff, septic seepage, atmospheric deposition, and decaying vegetation. Eutrophic water bodies experience chronic algae blooms, oxygen crashes, fish kills, and shifts from clear-water to turbid-water states. Florida's Lake Okeechobee, Lake Apopka, and many smaller lakes are textbook eutrophic systems. Reversal requires nutrient-load reduction at the source — treating the bloom does nothing for the underlying state.