Complex sentence: The North Fork St. Lucie River (NFSLR) Aquatic Preserve is a freshwater system upstream and a brackish system near the St. Lucie Estuary, Florida, and was designated as an aquatic preserve in 1972.
Split into simpler sentences: The North Fork St. Lucie River Aquatic Preserve (NFSLR) is a freshwater and brackish water system connected to St. Lucie Estuary in Florida. It was designated as an aquatic preserve in 1972.