In 200 AD, prehistoric people living near Lake Okeechobee constructed the earliest-known canal in North America. According to archaeologists, early Native American societies such as the one living nearly 2,000 years ago in what is now known as Ortona, Florida, constructed canals for fishing and transportation. Canals constructed by Florida land developers during the twentieth century provided similar benefits for contemporary citizens.
Today, thousands of miles of canals and their water-control structures are carved into Florida's landscape, especially in the southeastern parts of the state. Canals are artificial waterways that modify existing rivers or streams; or are dug into wetlands or uplands for navigation, drainage and flood control, irrigation, access, and recreation. Florida canals range from a few feet to hundreds of feet wide, and from a few feet to as deep as 35 feet.
Canals provide many benefits—without them, the state from Orlando southward would be unable to accommodate the millions of residents and enterprises that now call south Florida home.
However, canals also present many challenges to aquatic plant managers who must keep waters flowing. Without regular and frequent management, aquatic plants would quickly clog these systems, rendering them useless for flood control, navigation, and recreation.
River and stream channels that have been widened, deepened, or straightened are forever changed. Altering water flow, bank slope, oxygen and light levels, and bottom composition and structure affects fish and wildlife as well as plant growth. Canals constructed in wetlands or uplands quickly fill with both native and non-native aquatic plants. Managers must decide how and to what extent aquatic plants should be managed to accommodate the functions of these artificially constructed waterways.
Canals in Florida serve many purposes: drainage, flood control, irrigation, navigation, and recreation. They also create waterfront home sites.
Florida rainfall averages nearly 60 inches per year. Therefore, drainage is a major function of canal systems. Canals hold excess surface water and protect tens of thousands of homes and businesses and millions of acres of agriculture. Canal systems are operated by water management districts, special drainage districts, other local governments, and property owners.
Florida is a frequent target for tropical storms and hurricanes from the Atlantic Ocean and Gulf of Mexico. These tropical cyclones may drop 20 inches or more of rain in a single day. Flood control
Florida has a rich history of agriculture which boomed with the construction of canals that drained fertile land, controlled seasonal flooding, and provided reliable irrigation. Farmers can drain water from their farms during the wet season and retrieve stored water during the dry season. Major economic crops dependent on south Florida's water control systems include sugarcane (first planted in 1917), peanuts and potatoes (1920s); beans, tomatoes and peppers (1930s); rice (1950s); and St. Augustine grass (1950s). Major citrus groves moved south after devastating freezes in central Florida during the 1970s and 1980s. Cattle became a major industry in the area in the 1950s.
Navigation throughout Florida is facilitated by canal systems that provide navigable waterways for commercial and recreational boating.
Unlike central and northern Florida, the southern part of the state has relatively few natural freshwater recreation areas. Canals are home to a variety of freshwater game fish, offer thousands of acres of surface area, and are easily accessible for boat and shore fishing.
Residential property in Florida has relatively greater real estate value when adjacent to canals. Canals provide boating access to coastal waters and to most of Florida's large public lakes and navigable waters. Canals which are privately owned provide valuable local taxes, part of which are used for plant-management activities in the canals. Residential canals provide drainage and flood control, and their spoil is spread next to the canals to raise the elevation of surrounding areas, providing an extra measure of flood protection.
|Dams prevent rivers from draining during dry season, enabling navigation throughout the year. River water flows into pools created by the dam and excess water runs over the dam into the next pool.|
|Locks are concrete chambers that enable boats to travel from one dammed pool to the next. Gates open and close when the water level is equal on both upstream and downstream sides of the lock. Filling and emptying of the lock is conducted by valves within its walls. No pumping is necessary as water flows in and out of the chambers by gravity.|
|Culverts are buried pipes that conduct water underneath roadways or into canals. Channels are navigable pathways in waterbodies that are at least nine feet deep.|
|Weirs are crested overflow structures built over canals as a means of measuring water discharge.|
Virtually all canals in Florida are susceptible to serious weed infestations that interfere with navigation, flood control
Plant destroying and harvesting machines (described on the mechanical controls page) can provide immediate relief for clogged canals. However, harvesters work slowly and are restricted to the central channel. Sterile grass carp (are plant-eating fish used as a biological control for submersed plants in canals. However, the non-native grass carp must be confined, which is difficult in canals. The most efficient means of aquatic weed control in canals is the use of herbicides (described on the chemical control page).
Despite the adverse effects of various plant management techniques, maintaining the proper functioning of canals is essential in Florida.
Canals are now permanent features of Florida's landscape. Although necessary, canals have negative environmental effects.
Very long and/or dead-end canals usually do not have adequate water circulation which leads to inadequate flushing and water turnover in many canals. Such conditions result in decreased dissolved-oxygen concentrations, increased pollution loading, decreased plant photosynthesis