Water Management in the Everglades FINAL
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The Everglades are one of the most unusual subtropical wetland ecosystems in the world. Historically, they consisted of a broad shallow Òriver of grassÓ covering about 11,000 m2 extending from the Kissimmee River to Lake Okeechobee and finally to the Florida Bay (Perry, 2004). The term Òriver of grassÓ describes the abundance of sawgrass throughout this ecosystem. This ecosystem is characterized by its shallow sheet flow, low nutrient levels, and temporal patterns of water flow (Chimney, 2006). The everglades once consisted of sawgrass marshes, wet prairies, sloughs, tree islands, and mangrove estuaries (Chimney, 2006). The variety of different habitats allowed for a diverse group of organisms to survive there such as alligators, several species of wading birds, manatees and many others. Due to human development the Everglades are one of the most endangered ecosystems in the country.
The formation of the Everglades was dependent on the natural occurrences of rain and fire. The hydrologic cycle was also naturally maintained. 90% of the water that is contained in the Everglades is derived from the rainfall in southern Florida (Chimney, 2006). The original flow of the Everglades started with the rainfall that was collected into the Kissimmee River, flowed down to Lake Okeechobee, and then meandered through the Everglades until it reached the Florida Bay. Starting in mid-May and going on through October is considered the wet season. This is when approximately 75% of the annual precipitation occurred (Kushlan, 1987). During this time the water level throughout the ecosystem rose. However, during the dry season evaporation exceeded rainfall so the water level would decrease. This is when there were high chances of fire which also helped shape this ecosystem. Today, large amounts of water are compartmentalized and highly regulated as to when water will be released (Kushlan 1987). As a result of this the hydrological regime has been greatly altered. Alteration of this ecosystem by humans for agriculture and development has caused these fires to shift to the winter. The timing and size of these fires had a direct impact on the plants surrounding the Everglades.
The motives behind the water management of this ecosystem have greatly changed throughout the years. The management of this ecosystem has been dependent on the problems and needs of the inhabitants of southern Florida. As the needs for water and land use changed so did the water management practices. Water management in the Everglades can be characterized into four distinct eras. The first era focused on draining the Everglades in order to use the land for agricultural and urban development (Davis, et al, 1994)). The attention then shifted to constructing elaborate canals and levees to control and help prevent flooding. Next the water management was focused on drought management and the problem of water shortages. Currently the management is focused on restoring the ecosystem and fixing the problems created by past water management policies.
Efforts began in the early 1900Õs to manage the surface water of the everglades by diverting the flow and draining the water of the Everglades after a devastating flood occurred in 1903 (Davis et al, 1994). The flood had drastic effects on the crops and agriculture of southern Florida. Plans were put into action and four major canals were dug that dissected the Everglades from Lake Okeechobee to the Atlantic Ocean (6). These canals later became the core of a water control system for flood control (Davis et al, 1994)). These canals diverted the water flow and made the region dry enough for crops and farms to survive and they also opened the land up for urban development. To fund and manage these large scale projects the Florida Drainage District was created. However, in the 1940Õs financial problems caused the construction to stop (Davis et al, 1994).
During the years of 1926 and 1928, two large hurricanes bombarded southern Florida causing large floods and claiming many lives. This natural disaster caused a major shift from drainage of the Everglades to flood control. In 1948 the US Army Corps of Engineers was authorized by Congress to construct a plan to provide flood control for Southern Florida. This plan was called the Central and South Florida project and the major goal was to remove water by conveying the majority of the rainfall to the east or west coast of the state. The four canals previously built provided the backbone for this plan (Davis et al, 1994)). In order for this goal to be accomplished over 1000 miles of canals, 720 miles of levees, 16 pumping stations, and 200 control structures were built to stabilize the water levels and allow for them to be regulated (Perry 2004). While controlling the flooding of the Everglades, 70% of the original water flow was completely lost as a result of the canals that were built (Perry, 2004). This water was diverted to surrounding estuaries without even entering the Everglades ecosystem.
This project also resulted in the creation of specific land use areas, the Everglades Agricultural Area (EAA), Water Control Areas (WCA), and the Everglades National Park (ENP). The EAA is a 700,000 acre region in the northern Everglades that was drained in the early 1900Õs and is used for agriculture, primarily sugar cane and vegetables (Anderson, 1995). The WCAÕs are shallow reservoirs that were used to prevent flooding during the wet season and retain water during the dry season (Kushlan, 1987). Throughout the Everglades there are a total of five WCAÕs. The ENP is a portion of the everglades that is devoted to protecting and maintaining their original quality. As a result of attempting to strictly regulate the flow of the everglades, the natural hydrologic regime was substantially altered. The water that flows through the WCAÕs is directed through canals where it is then stopped and held behind levees to raise water levels. In some areas the water level difference between WCAÕs can be over 1 meter (Palaseanu, 2007). The water that is held in WCAÕs is then released at biologically inappropriate time which causes many problems for the organisms that live in this ecosystem (Kushlan, 1987). The water that flows into the ENP has been limited to four gated structures. The water then is split up and flows in two different directions through the state. It can be seen that the water flowing through this ecosystem is no longer flowing on its natural path and this had many effects on the ecosystem. As a result of the drainage, there was an increased amount of land available for agricultural and urban development. This caused the size of the Everglades to be reduced by 50%. It also allowed for the population of Florida to increase tremendously.
The combination of 70 years of drainage and drought control of the Everglades and a large increase in the population in southern Florida led to severe concerns about the water supply. As a result of this Florida created the Water Resources Act. This piece of legislation created 5 regional water management districts. The purpose of these districts was to protect the water supply, ensure flood control, and improve the quality of the water (Anderson, 1995). One of the 5 districts is The Southern Florida Water Management District (SFWMD) which includes Lake Okeechobee and the Everglades (Anderson, 1995). This district in particular plays a very large role in the restoration of the Everglades. One of the jobs of the SFWMD is to manage the hydrology of the Everglades through one of the worldÕs largest and most complex draining systems consisting 2400 km of canals and levees, 125 major water control structures, 18 major pump stations and hundreds of smaller structures (Chimney, 2006). Another important job of the SFWMD is to explore and create new hydrological simulation models to help restore the natural water flow (Walters, 1992).
The past water management policies have greatly affected the health of the ecosystem. There has been a significant loss in the habitats of the everglades as well as large declines in the population of wildlife in the area (2). There has also been many exotic invasive species that have made the Everglades their home and this has had drastic effects on the native organisms. The overall water quality of the ecosystem has greatly declined.
The significant loss of habitats and declines in native organismsÕ population is a result of the unnatural hydrologic regime of the Everglades. When the water management practices were focused on providing drought control the water levels were kept abnormally high which lead to a decline in the plant species. When the water levels were kept low, during the flood control era, the habitats of many of the wading birds of the Everglades were greatly altered or destroyed. The effects of water control can be directly seen when looking at specific species such as the American Alligator (Alligator mississippiensis). The reproductive success of this organism depends on the water levels during the nesting season (Kushlan, 1990). If the water levels are too high the nest will flood and the eggs die. This has repeatedly happened and it is a direct result of the water management (Kushlan, 1987). It has also been shown that there has been a significant decrease in the population of wading birds in the area of the Everglades (Ogden, 1994)
In addition to the decline in habitats and wildlife, the quality of water has greatly declined. As previously stated with the creation of the Central and South Florida project there was a creation of different land areas. These specific land use areas added to the problems that were occurring in the Everglades. Most of the EAA runoff flows directly into the WCAÕs. This water carries elevated concentrations of nutrients, such as phosphorus, as a result of the fertilizers that were being used for farming. This increased level of phosphorus caused eutrophication in the WCAÕs which led to great algal blooms. In response to all of these problems The Florida legislature passed The Florida Surface Water Improvement and Management (SWIM) (Anderson, 1995). The purpose of SWIM was to implement plans to help restore the health of the Everglades. One the plans that was put into action by SWIM was the his plan required the agriculture to implement best management practices (BMP) to reduce the phosphorus loading of the Everglades which would help prevent eutrophication (Anderson, 1995). The SWIM act set of phosphorus concentration limitations to decrease the amount of phosphorus in the EAA runoff (Anderson, 1995).
Based on the problems that the past water management practices have caused, it is obvious that drastic changes need to be made in order to protect this ecosystem. With the health of the ecosystem in a constant decline the overall concern about the Everglades led to the formation of the Comprehensive Everglades Restoration Plan (CERP). The CERP is a modification to the already existing Central and South Florida Project and was part of the Federal Water Resources Development Act of 2000. This plan is described as one of the worldÕs largest ecosystem restoration projects and is estimated to cost $8 billion and take place over a 30 year period of time (Perry, 2004). The plan has many components but overall it contains a framework to restore, protect and preserve the water resources of southern Florida, mainly the Everglades. One of the main goals of the plan is to restore the natural flow of water through the Everglades while increasing the quality of the water. To do this many of the existing canals and levees will be removed to help improve the overland flow of the water.
It can be seen that the quality of the Everglades has been changing ever since water management practices have began. What was once a free flowing Òriver of grassÓ that was sustained by the natural occurrences of rainfall and fires in the area, now consists of a complex system of canals and levees in order to control the water of the Everglades. The need for the management of the water has changed over time yet the effects are undeniable. The motives have shifted from flood control, to drought and water supply management, to finally where the situation stands today, restoring the Everglades. Over the years many different plans have been implemented which led to the construction of the many different water control structures that exist in the Everglades today. With the help of the United States government and the state of Florida this ecosystem is in the process of being restored, but it is not a simple task
Works Cited
Anderson, DL. Flaig, EG. (1995) Agricultural Best Management Practice and Surface Water Improvement and Management. Water Science and Technology. 31(8), 109-121.
Chimney, MJ, Goforth, G. (2006). History and Description of the Everglades Nutrient Removal Project, a Subtropical Constructed Wetland in South Florida (USA). Ecological Engineering. 27(4), 268-278.
Chimney, MJ, Nungesser, MK. (2006). A Hydrologic Assessment of the Everglades Nutrient Removal Project, a Subtropical Constructed Wetland in South Florida (USA). Ecological Engineering. 27(4), 331-334.
Davis, M., Ogden, J., Park, W. (1994). Everglades: the ecosystem and its restoration. CRC Press
Kushlan, JA. (1987). External Threats and Internal Management: They Hydrologic Regulation of the Everglades, Florida, USA. Environmental Management. 11(1), 109-119.
Kushlan, JA, Jacobson, T. (1990) Environmental Variability and the Reproductive Success of Everglades Alligators. Journal of Herpetology. 24(2). 176-184.
Ogden, JC. (1994) A comparison of wading bird nesting colony dynamics (1931-1946 and 1974-1989) as an indication of ecosystem conditions in the southern Everglades. 530-570.
Palaseanu, M., Pearlstine, L. (2007). Estimation of Water Surface Elevations for the Everglades, Florida. Computers and Geosciences. 34, 815-826.
Perry, W. (2004). Elements of South FloridaÕs Comprehensive Everglades Restoration Plan. Ecotoxicology. 13, 185-193.
Walters, C et al. (1992). Experimental Policies for Water Management in the Everglades. Ecological Applications. 2(2), 189-202.
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