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87-456: The Collins Bridge was a bridge that crossed Biscayne Bay between Miami and Miami Beach, Florida . At the time it was completed, it was the longest wooden bridge in the world. It was built by farmer and developer John S. Collins (1837–1928) with financial assistance from automotive parts and racing pioneer Carl G. Fisher . Fisher, an auto parts magnate, loaned Collins $ 50,000 in 1911 ($ 1.6 million, adjusted for current inflation) to complete

174-557: A barrier island and Miami on the mainland , from Dumfoundling Bay on the north to the Rickenbacker Causeway to the south. Other municipalities on the western shore of the lagoon include Aventura (on Dumfoundling Bay), North Miami Beach, North Miami , and Miami Shores . Municipalities bordering the lagoon on the barrier islands north of Miami Beach include Sunny Isles Beach, Bal Harbour , Bay Harbor Islands , Surfside , and Indian Creek Village . North Bay Village

261-402: A dragline . This technique is often used in excavation of bay mud . Most of these dredges are crane barges with spuds , steel piles that can be lowered and raised to position the dredge. A backhoe/dipper dredger has a backhoe like on some excavators . A crude but usable backhoe dredger can be made by mounting a land-type backhoe excavator on a pontoon . The six largest backhoe dredgers in

348-490: A capacity of 6,000 cubic metres per hour (59,000 cu ft/ks). An even larger dredger, retired in 1980, was the U.S. Army Corps of Engineers Essayons , which was 525.17 feet (160.07 m) long. The Mallard II , a clamshell dredger that maintains levees in San Francisco Bay , has operated continuously since being built in 1936. Dredgers are often equipped with dredge monitoring software to help

435-614: A causeway and bridges connecting Key Biscayne to the Ragged Keys and beyond on the grounds that such construction would block the free outflow of storm surges from the bay across the flats to the ocean. It is believed that it does moderate the effects of storm surges on the bay. The transportation of sand southward along the Atlantic Coast of Florida by longshore drift ends in the area of the Safety Valve. The structure of

522-439: A few different types of dredge hoses that differ in terms of working pressure, float-ability, armored or not etc. Suction hoses, discharge armored hoses and self-floating hoses are some of the popular types engineered for transporting and discharging dredge materials. Some even had the pipes or hoses customised to exact dredging needs etc. Other times, it is pumped into barges (also called scows ), which deposit it elsewhere while

609-567: A few situations the excavation is undertaken by a specialist floating plant , known as a dredger. Usually the main objectives of dredging is to recover material of value, or to create a greater depth of water. Dredging systems can either be shore-based, brought to a location based on barges , or built into purpose-built vessels. Dredging can have environmental impacts: it can disturb marine sediments , leading to both short- and long-term water pollution , damage or destroy seabed ecosystems , and can release legacy human-sourced toxins captured in

696-527: A lagoon behind the ancient reef that became the Key Largo limestone, and is the same age as the Key Largo limestone. The limestone bottom of the lagoon is overlain by 1.2 to 4.6 metres (3.9 to 15.1 ft) of sand, carbonate mud, and coral rubble sediments. For purposes of discussion and analysis, Biscayne Bay is often divided into three sections: North Bay, Central Bay, and South Bay. The North Bay of Biscayne Bay principally lies between Miami Beach on

783-643: A location in the Florida Keys. Due to its distance from the open ocean and the restrictive passages between other components of Biscayne Bay, Manatee Bay experiences low tidal exchange, while the C-197 canal allows fresh water from the C-111 canal to flow into Manatee Bay. Salinity levels in Manatee Bay range from 14 parts-per-thousand (ppt) to 45 ppt (seawater has an average salinity of 35 ppt). In July 2023,

870-482: A long tube like some vacuum cleaners but on a larger scale. A plain suction dredger has no tool at the end of the suction pipe to disturb the material. A trailing suction hopper dredger (TSHD) trails its suction pipe when working. The pipe, which is fitted with a dredge drag head , loads the dredge spoil into one or more hoppers in the vessel. When the hoppers are full, the TSHD sails to a disposal area and either dumps

957-555: A maximum depth of 4 metres (13 ft). The eastern rim of the lagoon is based on an ancient coral reef which existed along the southeastern edge of the Florida Platform about 100,000 years ago. The ensuing Wisconsin glaciation lowered sea levels, leaving the reef above water. The dead reef became fossilized, forming the Key Largo Limestone (commonly called "coral rock"). Key Largo Limestone underlies

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1044-616: A point between North Miami Beach and Sunny Isles Beach south to the Arsenicker Keys and the Cutter Bank just to the east of those islands. Many discussions about the lagoon include Dumfoundling Bay, a small lagoon just north of North Miami Beach, as part of Biscayne Bay, and include Card Sound and Barnes Sound , in southern Miami-Dade County adjacent to Key Largo , as either part of a system of connected lagoons including Biscayne Bay, or as part of Biscayne Bay itself. The lagoon

1131-496: A process known as dewatering. Current dewatering techniques employ either centrifuges, geotube containers, large textile based filters or polymer flocculant /congealant based apparatus. In many projects, slurry dewatering is performed in large inland settling pits, although this is becoming less and less common as mechanical dewatering techniques continue to improve. Similarly, many groups (most notable in east Asia) are performing research towards utilizing dewatered sediments for

1218-652: 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

1305-411: A shipping channel through coral reefs . A bucket dredger is equipped with a bucket dredge, which is a device that picks up sediment by mechanical means, often with many circulating buckets attached to a wheel or chain . A grab dredger picks up seabed material with a clam shell bucket , which hangs from an onboard crane or a crane barge , or is carried by a hydraulic arm, or is mounted like on

1392-687: A small park. It is located on the John F. Kennedy (79th Street) Causeway in North Bay. The City of Miami has many parks fronting on the lagoon, the more important of which are Bayfront Park , Alice Wainwright Park , Margaret Pace Park , Maurice A. Ferré Park , Morningside Park, and Peacock Park . Public marinas on Biscayne Bay operated by the City of Miami include: Dinner Key Marina, Miami Marine Stadium Marina, and Miamarina at Bayside . The Biscayne Bay Aquatic Preserve includes most of Biscayne Bay (in

1479-512: A surface area of 221 square miles (570 km ). Various definitions may include Dumfoundling Bay, Card Sound, and Barnes Sound in a larger "Biscayne Bay", which is 60 miles (97 km) long with a surface area of about 271 square miles (700 km ). Hernando de Escalante Fontaneda related in the 16th century that a sailor from the Bay of Biscay called the Viscayno or Biscayno had lived on

1566-526: Is a bar or blade which is pulled over the seabed behind any suitable ship or boat. It has an effect similar to that of a bulldozer on land. The chain-operated steam dredger Bertha , built in 1844 to a design by Brunel and as of 2009 was the oldest operational steam vessel in Britain, was of this type. This is an early type of dredger which was formerly used in shallow water in the Netherlands. It

1653-447: Is at Black Point. Dredging Dredging is the excavation of material from a water environment. Possible reasons for dredging include improving existing water features ; reshaping land and water features to alter drainage , navigability , and commercial use; constructing dams , dikes , and other controls for streams and shorelines; and recovering valuable mineral deposits or marine life having commercial value. In all but

1740-596: Is bordered on its west by the mainland of Florida, and is separated from the Atlantic Ocean to the east by a string of barrier islands in the northern part of the lagoon, a large shoal in the central section, and the northernmost of the Florida Keys in the south. The lagoon is about 35 miles (56 km) long from Dumfoundling Bay (25° 58′ North latitude) (north of North Miami Beach) to Card Sound, and another 25 miles (40 km) to Jewfish Creek (25° 24′ North latitude), if Card Sound and Barnes Sound are included in

1827-400: Is located on two artificial islands in the middle of the lagoon. North Bay is the part of the lagoon that has been most modified by human works, including channels and other dredged areas, and spoil banks and artificial islands created with material dredged from channels. More than 40% of the area of North Bay had either been dredged or filled to form artificial islands, and more than half of

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1914-424: Is mainly used in harbours and other shallow water. Excavator dredge attachments The excavator dredge attachment uses the characteristics of cutter-suction dredgers, consisting of cutter heads and a suction pump for transferring material. These hydraulic attachments mount onto the boom arm of an excavator allowing an operator to maneuver the attachment along the shoreline and in shallow water for dredging. This

2001-442: Is now Fisher Island at the south end of Miami Beach . The opening of Government Cut in 1905 separated Fisher Island from Miami Beach and slightly shortened the barrier spit. The dredging of Baker's Haulover Inlet in 1925 across the barrier spit near the north end of the bay converted that part of the barrier spit where Miami Beach was located into a barrier island. Modification of the flow of fresh water through waterways, and

2088-491: Is the least affected by human activities, although it also suffers from the loss of natural fresh water flow. The Turkey Point Nuclear Generating Station is a significant presence on the mainland shore. Card Sound is an extension of Biscayne Bay to the south of South Bay. Little Card Sound is the next south, separated from Card Sound by Card Bank. The causeway of the Card Sound Bridge now separates Barnes Sound to

2175-410: Is usually sucked up by a wear-resistant centrifugal pump and discharged either through a pipe line or to a barge. Cutter-suction dredgers are most often used in geological areas consisting of hard surface materials (for example gravel deposits or surface bedrock) where a standard suction dredger would be ineffective. They can, if sufficiently powerful, be used instead of underwater blasting. As of 2024,

2262-486: The Leiv Eriksson are: 46,000 cubic metre hopper and a design dredging depth of 155 m. Next largest is HAM 318 ( Van Oord ) with its 37,293 cubic metre hopper and a maximum dredging depth of 101 m. A cutter-suction dredger's (CSD) suction tube has a cutting mechanism at the suction inlet. The cutting mechanism loosens the bed material and transports it to the suction mouth. The dredged material

2349-742: The Cutler Fossil Site , a sinkhole that is now a couple of kilometers from the bay. At the time of European contact, in the early 16th century, the area around the bay was occupied by the Tequesta . The Tequesta belonged to the Glades culture , which had been in place for about 2,000 years. The chief town of the Tequesta, also called Tequesta, was on the bay at the mouth of the Miami River, from about 1200. The Miami Circle , just south of

2436-481: The Nile were channelled and wharfs built at the time of the pyramids (4000 BC), there was extensive harbour building in the eastern Mediterranean from 1000 BC and the disturbed sediment layers gives evidence of dredging. At Marseille , dredging phases are recorded from the third century BC onwards, the most extensive during the first century AD. The remains of three dredging boats have been unearthed; they were abandoned at

2523-696: The University of Miami 's Rosenstiel School of Marine, Atmospheric, and Earth Science are located on the southern end of Virginia Key , the only part of that island bordering on Central Bay. Grove Isle , near the Miami neighborhood of Coconut Grove , is an artificial island in Central Bay. The large marina at Dinner Key is also in Coconut Grove. Central Bay has been adversely affected primarily by bulkheading, urban runoff discharged by canals, and

2610-808: The Biscayne Bay Aquatic Preserves. Card Sound and Barnes Sound lie within the Florida Keys National Marine Sanctuary . The Crocodile Lake National Wildlife Refuge on Key Largo includes 650 acres (2.6 km ) of open water in Card Sound and Barnes Sound. Lobsters are protected year-round in the Biscayne Bay-Card Sound Lobster Sanctuary. The sanctuary includes all of the lagoon from a line running from Cape Florida to Matheson Hammock County Park south to

2697-538: The Card Sound Bridge and causeway. The sea level at Virginia Key has been rising at an average rate of 2.97 millimetres (0.117 in) a year from 1931 to 2020, equivalent to 0.97 feet (0.30 m) a century. The islands adjacent to the lagoon are low-lying and threatened with significant flooding in the near future. Gas and oil exploration wells have been drilled near the lagoon, although none reached exploitable deposits. Canals and quarries have disturbed

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2784-539: The Eastern edge of the barrier islands and the shoals (Safety Valve) along the northern and middle part of the lagoon. It makes a brief appearance at Soldier Key , in the middle of the Safety Valve, and rises above sea level to the south to form the upper Florida Keys. The western side of the bay has characteristics of an estuary , with 16 waterways, the largest of which is the Miami River , flowing into it. All of

2871-468: The Florida Keys north of Key Largo, are within the boundaries of Biscayne National Park . A number of other state and local parks front on the lagoon, primarily on North Bay and the northern rim of Central Bay. Bill Baggs Cape Florida State Park is located on the southern part of Key Biscayne. Oleta River State Park is located on the south side of the Oleta River where it flows into the segment of

2958-484: The Intracoastal Waterway connecting Dumfoundling Bay and North Bay, fronting on North Bay as it widens to the south. Miami-Dade County operates a number of parks with frontage on Biscayne Bay. Haulover Park is on the barrier island running north from Baker's Haulover Inlet. Crandon Park covers the northern part of Key Biscayne. The Vizcaya Museum and Gardens are located on the mainland in Miami near

3045-588: The MacArthur Causeway have been created, in whole or in part, with material dredged from the lagoon bottom. Most of the islands, such as the Venetian Islands, are residential. Brickell Key , another residential island, is just south of the mouth of the Miami River. Dodge Island , across the main ship channel to the south of the MacArthur Causeway, was enlarged in the 1960s when the Port of Miami

3132-927: The Miami-Dade County-Monroe County line, and from the limit of Florida territorial waters in the Atlantic to the Intracoastal Waterway in Biscayne Bay. When the Biscayne National Monument was upgraded to a National Park, all waters in the National Park were removed from the Biscayne Bay-Cape Florida to Monroe County Line Aquatic Preserve. The remainder of that preserve consists of about 4,163 acres (16.85 km ) of submerged lands near Key Biscayne. The two preserves are known collectively as

3219-414: The Safety Valve has been stable for at least the last century. (The area was called Bocas de Miguel de Mora on Spanish maps and derroteros during the era of Spanish Florida . ) Stiltsville is a collection of buildings on pilings on several sand flats at the northern end of the Safety Valve. What is now Biscayne Bay was a freshwater basin 4,000 years ago. As the sea level rose, ocean water entered

3306-481: The basin, turning it into an estuary/lagoon. Before the 20th century, a coastal ridge west of and parallel to the bay caused most of the ground water west of the ridge to flow towards the Everglades and Florida Bay , while ground water on the narrow coastal strip east of the ridge flowed into the bay. Freshwater marshes were located all along the western shore of the bay, and fresh water springs were located along

3393-545: The bay was in the news when a bouy there recorded a water temperature of 101.1 °F (38.4 °C). The Safety Valve is a series of shallow sand flats separated by tidal flow channels, stretching about 8 miles (13 km) from the south end of Key Biscayne to the Ragged Keys just north of the Florida Keys . The term "safety valve" was applied to the tidal flats by Ralph Munroe , who argued against building

3480-690: The bedrock on the shores of the lagoon. Miami-Dade County operates a 300-acre (120 ha) landfill at Black Point adjacent to the lagoon. Miami-Dade County operates three wastewater treatment plants close to the lagoon. The oldest is the Central District Wastewater Treatment Plant on Virginia Key. The North District Wastewater Treatment Plant is in North Miami, and the South District Wastewater Treatment Plant

3567-532: The beds of streams. During the renaissance Leonardo da Vinci drew a design for a drag dredger. Dredging machines have been used during the construction of the Suez Canal from the late 1800s to present day expansions and maintenance. The completion of the Panama Canal in 1914, the most expensive U.S. engineering project at the time, relied extensively on dredging. These operate by sucking through

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3654-620: The bottom of the harbour during the first and second centuries AD. The Banu Musa brothers during the Muslim Golden Age in while working at the Bayt-Al-Hikmah (house of wisdom) in Baghdad, designed an original invention in their book named ‘ Book of Ingenious Devices ’, a grab machine that does not appear in any earlier Greek works. The grab they described was used to extract objects from underwater, and recover objects from

3741-508: The bridge had a steel lattice truss design, while the ends were primarily wooden, as well as the deck being wooden for the entire length. The original wooden causeway was replaced in 1925 by a series of arch drawbridges and renamed the Venetian Causeway . Biscayne Bay The part of the lagoon that is traditionally called "Biscayne Bay" is approximately 35 miles (56 km) long and up to 8 miles (13 km) wide, with

3828-470: The bridge when Collins' money ran out. Collins, then 75 years old, traded Fisher 200 acres (81 ha) of land on Miami Beach for the loan. The 2.5-mile (4.0 km) wooden toll bridge opened on June 12, 1913, providing a critical link to the newly established Miami Beach, formerly accessible only by a ferry service. The total cost of the Collins Bridge was in excess of $ 150,000. The middle of

3915-605: The construction industry. Dredging is a four-part process: loosening the material, bringing the material to the surface (together extraction), transportation and disposal. The extract can be disposed of locally or transported by barge or in a liquid suspension in pipelines. Disposal can be to infill sites, or the material can be used constructively to replenish eroded sand that has been lost to coastal erosion , or constructively create sea-walls, building land or whole new landforms such as viable islands in coral atolls . Ancient authors refer to harbour dredging. The seven arms of

4002-495: The dredge continues its work. A number of vessels, notably in the UK and NW Europe de-water the hopper to dry the cargo to enable it to be discharged onto a quayside 'dry'. This is achieved principally using self discharge bucket wheel, drag scraper or excavator via conveyor systems. When contaminated (toxic) sediments are to be removed, or large volume inland disposal sites are unavailable, dredge slurries are reduced to dry solids via

4089-482: The dredge operator position the dredger and monitor the current dredge level. The monitoring software often uses Real Time Kinematic satellite navigation to accurately record where the machine has been operating and to what depth the machine has dredged to. In a "hopper dredger", the dredged materials end up in a large onboard hold called a "hopper." A suction hopper dredger is usually used for maintenance dredging. A hopper dredge usually has doors in its bottom to empty

4176-425: The dredged materials, but some dredges empty their hoppers by splitting the two-halves of their hulls on large hydraulic hinges. Either way, as the vessel dredges, excess water in the dredged materials is spilled off as the heavier solids settle to the bottom of the hopper. This excess water is returned to the sea to reduce weight and increase the amount of solid material (or slurry) that can be carried in one load. When

4263-557: The environment, including the following: The nature of dredging operations and possible environmental impacts requires that the activity often be closely regulated and requires comprehensive regional environmental impact assessments alongside continuous monitoring. For example, in the U.S., the Clean Water Act requires that any discharge of dredged or fill materials into "waters of the United States," including wetlands,

4350-527: The form of a scoop made of chain mesh, and are towed by a fishing boat . Clam-specific dredges can utilize hydraulic injection to target deeper into the sand. Dredging can be destructive to the seabed and some scallop dredging has been replaced by collecting via scuba diving . As of June 2018, the largest dredger in Asia is MV  Tian Kun Hao , a 140-metre (460 ft) long dredger constructed in China, with

4437-447: The hopper is filled with slurry , the dredger stops dredging and goes to a dump site and empties its hopper. Some hopper dredges are designed so they can also be emptied from above using pumps if dump sites are unavailable or if the dredge material is contaminated. Sometimes the slurry of dredgings and water is pumped straight into pipes which deposit it on nearby land. These pipes are also commonly known as dredge hoses , too. There are

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4524-501: The lagoon. The lagoon is 8 miles (13 km) across at its widest point. The lagoon, from Dumfoundling Bay to the Arsenicker Keys, has a surface area of about 572 square kilometres (221 sq mi). The larger lagoon, including Card Sound and Barnes Sound, has a surface area of about 703 square kilometres (271 sq mi). It has an average depth of 1.8 metres (5.9 ft) and, except where channels have been dredged ,

4611-629: The loss of natural fresh water flow. South Bay is nearly as large as Central Bay, and is defined as extending from the Featherbed Bank to the Arsenicker Keys , or to Cutter Bank, which is to the east of the Arsenicker Keys. (Brown et al. define South Bay as consisting of Card Sound and Barnes Sound.) It is separated from the ocean by the northernmost of the Florida Keys , from Boca Chita Key to Old Rhodes Key . Fresh water sources for South Bay include Black Creek, Goulds Canal, North Canal, Florida City Canal, and Model Land Canal. Tidal exchange with

4698-511: The lower east coast of Florida for a while after being shipwrecked, and a 17th-century map shows a Cayo de Biscainhos , the probable origin of the name for Key Biscayne . The lagoon was known as "Key Biscayne Bay" in the 19th century, finally shrinking to "Biscayne Bay" late in the 19th century. The lagoon has been known by several names. Juan Ponce de León called it Chequescha in 1513, and Pedro Menéndez de Avilés called it Tequesta in 1565. Those names are variant spellings of " Tequesta ",

4785-469: The material could well suit the building industry, or could be used for beach nourishment. Dredging can disturb aquatic ecosystems , often with adverse impacts. In addition, dredge spoils may contain toxic chemicals that may have an adverse effect on the disposal area; furthermore, the process of dredging often dislodges chemicals residing in benthic substrates and injects them into the water column . Dredging can have numerous significant impacts on

4872-467: The material through doors in the hull or pumps the material out of the hoppers. Some dredges also self-offload using drag buckets and conveyors. As of 2008 the largest trailing suction hopper dredgers in the world were Jan De Nul 's Cristobal Colon (launched 4 July 2008 ) and her sister ship Leiv Eriksson (launched 4 September 2009 ). Main design specifications for the Cristobal Colon and

4959-500: The middle third of the island on the eastern side of Central Bay. Fresh water sources for Central Bay include the Coral Gables Waterway and Snapper Creek . Tidal flow between Central Bay and the ocean is through Bear Cut between Virginia Key and Key Biscayne and across the Safety Valve. The development that has so transformed North Bay has spread over much of the northern shores of Central Bay. Miami Seaquarium and

5046-467: The most powerful cutter-suction dredger in the world is DEME 's Spartacus , which entered service in 2021. The auger dredge system functions like a cutter suction dredger, but the cutting tool is a rotating Archimedean screw set at right angles to the suction pipe. Mud Cat invented the auger dredge in the 1970s. These use the Venturi effect of a concentrated high-speed stream of water to pull

5133-410: The mouth of the Miami River, has been proposed to be post holes for a structure. The site was abandoned in about 1200, when the town site north of the river was occupied. Juan Ponce de León visited Biscayne Bay in 1513, and Pedro Menéndez de Avilés did so in 1565. Early accounts by Spanish explorers indicated the existence of one or more inlets somewhere on the long barrier spit then separating

5220-406: The name of the people who lived around the lagoon at the time. The British, during their occupation of Florida (1763–1783), called the lagoon "Cape River", "Dartmouth Sound", and "Sandwich gulph". Biscayne Bay is a semi- or subtropical lagoon extending most of the length of Miami-Dade County , from North Miami Beach to the upper Florida Keys . Biscayne Bay, in the strictest sense, extends from

5307-426: The nearby water, together with bed material, into a pipe. An airlift is a type of small suction dredge. It is sometimes used like other dredges. At other times, an airlift is handheld underwater by a diver . It works by blowing air into the pipe, and that air, being lighter than water, rises inside the pipe, dragging water with it. Some bucket dredgers and grab dredgers are powerful enough to rip out coral to make

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5394-553: The north to the Featherbed Bank, which runs across the bay from Black Point to Boca Chita Key . It is separated from the Atlantic Ocean by Key Biscayne , the Safety Valve , and the Ragged Keys , the northernmost of the Florida Keys . It is bordered on the western shore by the municipalities of Miami , Coral Gables , Palmetto Bay , Cutler Bay , and a portion of unincorporated Miami-Dade County. Key Biscayne occupies

5481-526: The northern edge of Central Bay. Matheson Hammock Park , the Charles Deering Estate , and Chapman Field Park are on the mainland along the western shore of Central Bay. Black Point Park and Marina and Homestead Bayfront Park are on the mainland on the western shore of South Bay. Black Point, Crandon, Haulover, Homestead Bayfront and Matheson Hammock parks have public marinas . The county also operates Pelican Harbor Marina, which includes

5568-602: The northern end of Biscayne Bay from the ocean (one called "Boca Rattones" appears on the 1770s map by Bernard Romans), but such inlets open and close over time. At the beginning of the 19th century, there was no inlet through the barrier spit between the New River inlet in Fort Lauderdale and Bear Cut, at the south end of what is now Virginia Key . Hurricanes in 1835 and 1838 opened a new inlet, Narrows Cut (now known as Norris Cut), separating Virginia Key from what

5655-591: The ocean is through Baker's Haulover Inlet , Government Cut , and Norris Cut. Northeast 163rd Street , or Sunny Isles Boulevard, connects North Miami Beach and Sunny Isles Beach across the section of the Intracoastal Waterway running between Dumfoundling Bay and Biscayne Bay proper. Five causeways cross North Bay between Northeast 163rd Street and the Rickenbacker Causeway, including: More than 20 islands in North Bay north from

5742-417: The ocean occurs through Sands Cut, Caesar's Creek and Broad Creek. Boca Chita Key, Elliott Key , and Old Rhodes Key were all enlarged by dredging in the first half of the 20th century. Boca Chita Key was the site of some construction in the early 20th century. Mark C. Honeywell bought the key in 1937, and built a large retreat on the island, including a 65-foot (20 m) tall faux lighthouse. South Bay

5829-593: The opening of Government Cut and the Baker's Haulover Inlet during the 20th century increased the salinity of the lagoon. Dredging of the ship channel and turning basin for the Port of Miami and other navigation channels, including the Intracoastal Waterway , has resulted in the build up of artificial islands in the Northern Bay. As of 1981 more than 40% of the area of North Bay had either been dredged or filled to form artificial islands. Seawalls line almost all of

5916-667: The production of concretes and construction block, although the high organic content (in many cases) of this material is a hindrance toward such ends. The proper management of contaminated sediments is a modern-day issue of significant concern. Because of a variety of maintenance activities, thousands of tonnes of contaminated sediment are dredged worldwide from commercial ports and other aquatic areas at high level of industrialization. Dredged material can be reused after appropriate decontamination. A variety of processes has been proposed and tested at different scales of application ( technologies for environmental remediation ). Once decontaminated,

6003-527: The remaining lagoon bottom is barren. Coastal wetlands have been almost eliminated in North Bay. Turbidity is high in North Bay due to erosion from spoil islands and banks, and the lack of vegetation on the lagoon bottom. The spoil islands host large quantities of invasive plant species . North Bay is separated from the Atlantic Ocean by barrier islands . Freshwater sources flowing into North Bay include Oleta River , Arch Creek , Biscayne Canal, Little River and Miami River. Tidal flow between North Bay and

6090-479: The seabed to bring the sediment in suspension, which then becomes a turbidity current , which flows away down slope, is moved by a second burst of water from the WID or is carried away in natural currents. Water injection results in a lot of sediment in the water which makes measurement with most hydrographic equipment (for instance: singlebeam echosounders) difficult. These dredgers use a chamber with inlets, out of which

6177-469: The seabed with its hull out of the water. Some forms can go on land. Some of these are land-type backhoe excavators whose wheels are on long hinged legs so it can drive into shallow water and keep its cab out of water. Some of these may not have a floatable hull and, if so, cannot work in deep water. Oliver Evans (1755–1819) in 1804 invented the Oruktor Amphibolos, an amphibious dredger which

6264-628: The sediment. These environmental impacts can reduce marine wildlife populations in some cases, contaminate sources of drinking water and interrupt economic activities such as fishing. Dredging is excavation carried out underwater or partially underwater, in shallow waters or ocean waters . It keeps waterways and ports navigable, and assists coastal protection, land reclamation and coastal redevelopment, by gathering up bottom sediments and transporting it elsewhere. Dredging can be done to recover materials of commercial value; these may be high value minerals or sediments such as sand and gravel that are used by

6351-412: The shore and on the bottom of the bay. Ralph Munroe noted in the late 19th century that potable water could be pumped from one of those bay bottom springs. Springs can still be found in the bay, but the water from them is now brackish. People lived in the area that is now Biscayne Bay long before the bay was formed. Human bones, teeth, and artifacts that are almost 11,000 years old have been found at

6438-445: The shoreline of North Bay. The bay 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. The first bridge across Biscayne Bay

6525-480: The south of Key Biscayne on the east, and just to the south of Chicken Key, part of the Charles Deering Estate, on the west. The southern part of the preserve includes Card Sound. The preserve includes about 69,000 acres (280 km ) of submerged land owned by the state. The Biscayne Bay-Cape Florida to Monroe County Line Aquatic Preserve was created in 1975. That preserve ran from Cape Florida to

6612-506: The south of Little Card Sound. Manatee Bay is to the west of Barnes Sound. Card Sound and Barnes Sound are bounded on the east by Key Largo . South Biscayne Bay is sometimes defined as including Card Sound and Barnes Sound. Barnes Sound is connected to Florida Bay through a few small channels. Manatee Bay is partially separated from Barnes Sound by Short Key and Main Key. In 1994, it was described as having particularly undisturbed habitat for

6699-427: The water is pumped with the inlets closed. It is usually suspended from a crane on land or from a small pontoon or barge. Its effectiveness depends on depth pressure. A snagboat is designed to remove big debris such as dead trees and parts of trees from North America waterways. Some of these are any of the above types of dredger, which can operate normally, or by extending legs, also known as spuds, so it stands on

6786-469: The waterways have saltwater intrusion control structures, which restrict the flow of saltwater inland, and regulate the flow of fresh water into the lagoon. Some fresh water enters the lagoon as groundwater flow from the Biscayne Aquifer . All of the bedrock under the lagoon west of the ancient reef, and the adjacent mainland, consists of Miami Limestone , an oolitic limestone that formed in

6873-586: The wider sense) that is not in Biscayne National Park. The preserve was created by the Florida Legislature in 1974, and then included all of Biscayne Bay from the Oleta River to the southern end of Card Sound. The preserve was split into two parts when the Biscayne National Monument became Biscayne National Park. The northern part extends from the headwaters of the Oleta River to the northern boundary of Biscayne National Park, just to

6960-705: The world are currently the Vitruvius, the Mimar Sinan, Postnik Yakovlev (Jan De Nul), the Samson (DEME), the Simson and the Goliath (Van Oord). They featured barge -mounted excavators. Small backhoe dredgers can be track-mounted and work from the bank of ditches. A backhoe dredger is equipped with a half-open shell. The shell is filled moving towards the machine. Usually dredged material is loaded in barges. This machine

7047-446: Was America's first steam-powered road vehicle. These are usually used to recover useful materials from the seabed. Many of them travel on continuous track . A unique variant is intended to walk on legs on the seabed. Fishing dredges are used to collect various species of clams , scallops , oysters or mussels from the seabed. Some dredges are also designed to catch crabs, sea urchins, sea cucumbers, and conch. These dredges have

7134-468: Was a flat-bottomed boat with spikes sticking out of its bottom. As tide current pulled the boat, the spikes scraped seabed material loose, and the tide current washed the material away, hopefully to deeper water. Krabbelaar is the Dutch word for "scratcher". A water injection dredger uses a small jet to inject water under low pressure (to prevent the sediment from exploding into the surrounding waters) into

7221-506: 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 . Most of Central Bay and almost all of South Bay, as well as the Safety Valve and

7308-493: Was moved there from the mainland north of Bayfront Park. The Miami Marine Stadium was built on the north side of the Rickenbacker Causeway extending from the east side of Virginia Key in the early 1960s. There are also many undeveloped spoil islands in North Bay, such as Sandspur Island and the Picnic Islands . Central Bay is the largest part of the bay. It extends from the Rickenbacker Causeway and Virginia Key on

7395-473: 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

7482-576: 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

7569-543: 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 bridge

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