A view of Miami South channel in the afternoon.
Biscayne Bay (Bahía Vizcaína in Spanish) is a lagoon that is approximately 35 miles (56 km) long and up to 8 miles (13 km) wide located on the Atlantic coast of South Florida, United States. It is usually divided for purposes of discussion and analysis into three parts: North Bay, Central Bay, and South Bay. Its area is 428 square miles (1,110 km2). The drainage basin covers 938 square miles (2,430 km2)
The North Bay of the Biscayne Bay lies between Miami Beach barrier island and Miami on the mainland. It has been severely affected over the last century by raw sewage releases, urban runoff, shoreline bulkheading, dredging, the creation of artificial islands and the loss of natural fresh water flow into the bay. However, water quality has steadily improved since regular monitoring began in 1979. North Bay accounts for only 10% of the water area of the bay.
Central Bay is the largest part of the bay. It is separated from the Atlantic Ocean by the Safety Valve. It has been adversely affected primarily by bulkheading, urban runoff discharged by canals, and the loss of natural fresh water flow.
South Bay is nearly as large as Central Bay, and is the least affected by human activities, although it also suffers from the loss of natural fresh water flow. South Bay is separated from the Straits of Florida by the northernmost of the Florida Keys, and includes Card Sound and Barnes Sound. It is connected to Florida Bay through a few small channels.
The first bridge across Biscayne Bay was the 2.5-mile (4.0 km) wooden Collins Bridge built in 1912 by John S. Collins and his son-in-law Thomas Pancoast, who formed the Miami Beach Improvement Corporation; financing was provided by Carl G. Fisher and the Miami banker brothers John N. Lummus and James E. Lummus. Construction began on July 22, 1912. Although the cost of the project was initially $75,000, the construction project faced delays and cost overruns. The budget was partially completed in 1913. The bridge was "hailed as the longest wooden vehicle bridge in the world, and opened up the area as a luxury winter resort and playground." The bridge terminated at the Dixie Highway, built by Carl G. Fisher. The bridge was a toll bridge; in 1920, the toll was reduced from 20 cents each way (for two-seat cars) to 15 cents one way (and 25 cents round-trip). The bridge was sold to the Biscayne Bay Improvement Association, which developed five artificial islands that became known as the Venetian Islands: Biscayne and San Marco in Miami, San Marino, Di Lido, and Rivo Alto in Miami Beach. The bridge was torn down in 1925 and replaced with the "more substantial" Venetian Causeway the next year.
The Lummus brothers lobbied for the county commission's support for a second causeway connecting Miami to the barrier islands of Miami Beach, and the County Causeway later the MacArthur Causeway opened on February 17, 1920. In 1925, Biscayne Point was created in Miami Beach's north end. In 1929, a third causeway crossed Biscayne Bay at Normandy Isle, which developer Henri Levy had created several years earlier by dredging and filling the south half of Meade Island. The Julia Tuttle Causeway was built in 1959.
Other causeways are the John F. Kennedy (79th Street) and Broad causeways (connecting the Miami mainland), and the Rickenbacker Causeway (connecting Miami to Key Biscayne). The Card Sound Bridge connects the mainland in the Homestead, Florida area to the northern part of Key Largo.