§ 33B-13. Description of the area

(a)

Boundaries of area.

Begin at the southwest corner of Section 18, Township 59 South, Range 38 East, Miami-Dade County, Florida; thence run north along the west line of Township 59 South, Range 38 East, and the west line of Township 58 South, Range 38 East, to the southeast corner of Section 36, Township 57 South, Range 37 East; thence run west along the south line of said Section 36 to the southwest corner of said Section 36; thence run north along the west line of Sections 36, 25, and 24 of Township 57 South, Range 37 East, to the northwest corner of said Section 24; thence run west along the south line of Sections 14, 15, 16, 17 and 18 of Township 57 South, Range 37 East, to the southwest corner of said Section 18; thence run north along the west line of Township 57 South, Range 37 East, the west line of Township 56 South, Range 37 East, and the west line of Township 55 South, Range 37 East to the northwest corner of Section 6 of said Township 55 South, Range 37 East; thence run northeasterly along the west line of Hiatus Lot 6 lying between Township 55 South, Range 37 East and Township 54 South, Range 37 East, to the southwest corner of Section 31, Township 54 South, Range 37 East; thence run north along the west line of Township 54 South, Range 37 East, to the point of intersection with the center line of U.S. Highway No. 41 (Tamiami Trail) in Section 7, Township 54 South, Range 37 East; thence run easterly along the center line of U.S. Highway No. 41 (Tamiami Trail) to the point of intersection with an imaginary extension of the center line of Levee L-31-N in Section 11, Township 54 South, Range 38 East; thence run south on the center line of Levee L-31-N through Sections 11, 14, 23, 26 and 35 of Township 54 South, Range 38 East; thence deflect southwesterly along the center line of Levee L-31-N in Hiatus Lot 2 lying between Township 54 South, Range 38 East, and Township 55 South, Range 38 East; thence deflect southerly along the center line of Levee L-31-N through Sections 2, 11, 14, and 23 of Township 55 South, Range 38 East; thence deflect southwesterly along the center line of Levee L-31-N through Sections 26 and 34, Township 55 South, Range 38 East; thence deflect southerly along the center line of L-31-N through Section 4, Township 56 South, Range 38 East; thence deflect southwesterly along the center line of Levee L-31-N through Sections 9, 17, and 18, Township 56 South, Range 38 East; thence deflect southerly along the center line of Levee L-31-N through Sections 19, 30 and 31, Township 56 South, Range 38 East, and Sections 6 and 7 of Township 57 South, Range 38 East to a point in said Section 7 where Levee L-31-N meets Canal C-111; thence continue south along the center line of Canal C-111 through Sections 7, 18, 19, 30 and 31 of Township 57 South, Range 38 East and through Section 6, Township 58 South, Range 38 East to the southeast corner of said Section 6; thence continue south along the said center line of Canal C-111 and along the east lines of Sections 7 and 18, Township 58 South, Range 38 East, to a point of deflection of the center line of Canal C-111 on the east line of said Section 18; thence deflect southeasterly along the center line of Canal C-111 through Sections 17, 20, 21, and 22, Township 58 South, Range 38 East to a point of intersection with the center line of Canal C-111E in said Section 22; thence run north on the center line of Canal C-111E to the midpoint of Section 22, Township 58 South, Range 38 East; thence run east across the midlines of Sections 22, 23, and 24 of Township 58 South, Range 38 East, and the midline of Section 19, Township 58 South, Range 39 East to a point of intersection with the center line of U.S. Highway No. 1 in said Section 19; thence run southeasterly along the center line of U.S. Highway No. 1 to a point of intersection with the south line of Section 17, Township 59 South, Range 39 East; thence run west along the south line of Sections 17 and 18, Township 59 South, Range 39 East and the south line of Sections 13, 14, 15, 16, 17, and 18, Township 59 South, Range 38 East, to the southwest corner of said Section 18, the same being the point of beginning, all the above lying and being in Miami-Dade County, Florida.

(b)

Environmental description and characteristics.

(1)

General. This area of critical environmental concern is located to the west of the urbanized part of the County contiguous to the Everglades National Park and encompasses approximately two hundred forty-two (242) square miles. Urbanized areas approach to within four (4) miles of its eastern boundary. Significant roads within the area are the Ingraham Highway (SR-27), Grossman Drive (SW 237 Avenue), U.S. Highway No. 1, the Context Road, Richmond Drive (SW 168 Street), Howard Drive (SW 136 Street), and Tamiami Trail (U.S. Highway No. 41).

(2)

Geology. The geology of the area is characterized by a highly transmissive water-bearing unconfined limestone formation known as the Biscayne Aquifer. The Biscayne Aquifer extends from the Broward-Palm Beach County boundary southward through all of Miami-Dade County. It is the sole source of potable water in Miami-Dade and Broward Counties and one of the most permeable aquifers in the world. The U.S. Environmental Protection Agency has recognized the importance of the Biscayne Aquifer by designating it as a sole source aquifer under the provisions of the Safe Drinking Water Act of 1974. The aquifer is exposed at the surface in must of the area or is covered by a thin mantle of soil and/or plant material. Within the aquifer, limestones make up approximately eighty (80) percent of the volume of the formation. Water levels within the rock formation annually rise to the surface in response to summer and fall precipitation, inundating vast portions of the designated area.

(3)

Groundwater. Groundwater flow in this area is generally in a southeasterly and southerly direction. Infiltrating rain in the western portion of the aquifer is the source of waters that flow into the deeper, eastern portions of the aquifer. As subterranean flows proceed eastward, shallower groundwater strata are replenished by direct percolation of precipitation and by infiltration from canals.

(4)

Physiography. The designated critical area is comprised of four (4) physiographic areas. From north to south they are: (a) The Shark River Slough, (b) the Rocky Glades, (c) Taylor Slough, and (d) the Southeast Saline Everglades.

a.

The Shark River Slough, also known as the Upper Shark River Basin, is a shallow surface water basin with an elevation of approximately six (6) feet above mean sea level. The slough has a northeasterly to southwesterly orientation and surface water flows in a southwesterly direction into the Everglades National Park during the wet season. During the rainy season, the water rises to a level of more than two (2) feet above much of the land surface. This part of the critical area contains some of the most significant areas of true "sawgrass everglades" that are found in South Florida. The overall slope of the land is very slight (two-tenths (0.2) feet per mile). The occurrence of three (3) basic vegetative communities within this region is indicative of very small differences in elevation of the terrain and average period of water inundation. The three (3) community types are (1) hammock forest/marsh thicket; (2) the sawgrass-rush-maidencane marsh; and (3) the rush-sawgrass-maidencane marsh. The forest and thicket communities occur as "islands" on discrete areas where the ground is a few inches higher than the surrounding marshes. The sawgrass-dominated marsh community is distributed over peat deposits, but at slightly lower elevation than the tree and shrub community. The wet prairie dominated by rush is found at slightly lower elevation than the sawgrass and usually corresponds with shallow soil deposits and a longer period of inundation.

Soils in the Shark River subarea are primarily accumulations of peat and muck which grade into rockland and outcrops of limestone in the south and southeast portions of the area. The peat soils are primarily the result of decaying sawgrass and other indigenous vegetation. Much of the Shark River Slough is covered by a periphyton or algal mat which is a complex biotic community consisting primarily of the blue-green and green algae, diatoms, desmids and other microscopic plants and animals. This periphyton community is understood to be the basis of the Everglades food web. The periphyton mat is dependent upon the maintenance of the natural hydroperiod for its continuation. In addition to its role as the primary producer in the Everglades food chain, the periphyton mat precipitates calcium carbonate which forms marl soil deposits. These marl deposits sometimes act to "cap" the rock surface in areas of the gladeland floor, thereby allowing the ponding of water which in turn aids in the formation of peat and muck soils.

Wildlife species that nest or feed in the Shark River Slough include the wood ibis, snowy and American egrets, Everglades kite, Everglades mink, round-tailed muskrat, white-tailed deer and American alligator. This area is especially valuable as a feeding area for a large population of wading birds during the early part of the dry season in South Florida.

b.

The Rocky Glades is the area between the Shark River Slough to the north and west, and Taylor Slough to the south. The Rocky Glades is not a discrete drainage basin, rather it is an area of "indeterminate drainage." Land elevations in the Rocky Glades range from eight and five-tenths (8.5) feet to five and five-tenths (5.5) feet above mean sea level (MSL). The land is characterized by rough, rocky outcroppings of limestone which has been eroded into pinnacle rock. Soils are primarily of the Rockland series and are principally comprised of eroded limestone with pockets of unconsolidated soil material. The natural vegetation in the area is a complex of muhly-sawgrass-rush and muhly-beardgrass prairies interspersed with small tree islands. Wildlife common to the prairies in Taylor Slough and Everglades National Park inhabit this area.

The Rocky Glades area plays a significant role in the recharge of groundwater and as a water storage area. Precipitation collects in depressions in the eroded limestone and percolates downward into the water table where it adds to the fresh water. The Rocky Glades is an important recharge area to groundwater flows toward public and private well fields in the vicinity of Homestead and Florida City.

c.

The portion of Taylor Slough within the East Everglades is the headwaters basin for a popular aquatic environment in Everglades National Park. The elevation in this subarea ranges from seven (7) to five and five-tenths (5.5) feet above MSL. The soils in Taylor Slough include perrine marls and rockland types. The predominant plant communities are the Muhly-sawgrass-rush, muhly-beardgrass and muhly prairies. Numerous small tree islands are also found in the headwaters of Taylor Slough. The wildlife in the Taylor Slough include some of the bird populations which are seem in Shark River Slough as well as those which are common in the prairies of the Rocky Glades. A large portion of Taylor Slough has been designated by the Secretary of the Interior as critical habitat for the Cape Sable sparrow, an endangered species.

Taylor Slough is one (1) of the three (3) principal drainage basins found in Everglades National Park. Because the headwaters of Taylor Slough are located in the East Everglades, the environmental characteristics of this subarea are critically important to downstream areas.

d.

The southeast Saline Everglades is the fourth distinct physiographic province in the designated area. Historically, fresh water flowed during the rainy season as a vast sheet from the vicinity of Florida City southward to the coastal estuaries. Although this flow pattern has been influenced by water management works in recent years, the Southeast Saline Everglades remains critically linked to the functioning of the brackish water estuaries of Florida Bay—the nurseries for infant shrimp and fish and other marine animals. Basic to the immense productivity of South Florida's estuaries is the inflow of fresh water from this subarea which moderates estuarine salinities and transports detrital material and other food sources for the juvenile marine organisms. Salinity is one of the most important factors affecting biological productivity in estuaries. Estuarine salinity is greatly influenced by upstream water levels. Maintenance of a broad brackish zone and a gradual salinity gradient in the coastal estuaries is a critical function of the sheet flow from the Southeast Saline Everglades. This salinity regime must be maintained if the high productivity of commercial fisheries is to be maintained. The soils of this area are marls and peats, often in overlying layers. Portions of the Southeast Saline Everglades have been designated by the Secretary of the Interior as critical habitat for the American crocodile. Other portions have been designated as critical habitat for the Cape Sable sparrow. An active eagle nest is also established in this subarea.

(5)

Topography. Land elevations in the area of critical environmental concern range from eight and one-half (8.5) feet above mean sea level (MSL) in the eastern part of the Rocky Glades subarea to five (5) feet above MSL in the Shark River Slough to less than one (1) foot above MSL in the Southeast Saline Everglades south and southwest of Canal 111. The groundwater table frequently rises to, or above, the land surface during the wet season. Water depths of three (3) feet are not uncommon in parts of the Shark River Slough, while in the Rocky Glades some areas remain dry except during water level peaks. Although surface flow in each of the physiographic areas is affected by distinct topographic characteristics, the maintenance of flow characteristics in each subarea is dependent upon maintenance of water levels in the other subareas.

(c)

Reasons for critical area designation. There are a number of significant reasons for designating the East Everglades as an area of critical environmental concern:

(1)

Recharge of Biscayne Aquifer. The area forms a part of the recharge zone of the Biscayne Aquifer and is directly upgradient from wellfields which provide irrigation and drinking water for Miami-Dade and Monroe Counties. High groundwater levels in the area maintain a groundwater gradient which provides for a subterranean flow of water, uncontaminated by development runoff and/or seepage, toward the major wellfields in Miami-Dade County and toward the Everglades National Park. In addition, the high groundwater levels in the area provide an essential freshwater head which prevents the intrusion of salt water into the base of the aquifer.

(2)

Surface water supply to Everglades National Park. Surface water within the area of critical environmental concern flows directly into Everglades National Park. The complex Everglades ecosystem is dependent upon a seasonal supply of high quality water flowing overland across the park and into Florida Bay. The continued supply of high quality fresh water to the intertidal nursery zones of Florida Bay and the Ten Thousand Islands is essential to the maintenance of paneid shrimp, oyster, menhaden and other fisheries of the Florida coast, the Gulf of Mexico and the Atlantic Ocean. In addition, overland freshwater flows are literally the lifeblood of the Everglades National Park, a resource of national and international importance. Furthermore, waters within Everglades National Park have been designated by the United States Environmental Protection Agency as national resource waters. Federal regulation prohibits any degradation of water quality of national resource waters.

(3)

Flood storage capacity. The area of critical environmental concern has historically functioned as an area that retains large quantities of surface water during highwater periods and releases water gradually by both surface flow and groundwater recharge. Although the East Everglades has been influenced by water management projects for other areas in recent times, the floodwater retention capacity is relatively unimpaired.

(4)

Water quality maintenance. The existing natural system within the area maintains a high quality water system that conveys essential nutrients downstream. This supply of high quality water and nutrients assures a diverse and dynamic micro and macro biota which are essential to the sustenance of the life cycles in the Everglades through the changing seasons. The ecosystem also provides a clean ground water supply for recharging the Biscayne Aquifer. Introduction of excess nutrients and other chemicals through development can quickly overload the natural assimilative capacity of the system.

(5)

Protection of economic vitality of Miami-Dade County. The large public expense that occurs when remote wetlands are converted to rural residential development is well known. In recognition of this condition, the Miami-Dade County Comprehensive Development Master Plan specified that public services should not be provided to the East Everglades at least through the year 2000. The public cost of development in the East Everglades would be much greater than in other remote areas due to the unresolvable conflict between protecting regional water supplies and providing flood protection to the area. The public health and nuisance problems that accompany residential development of floodplains and wetlands will create conditions that will require public investment in an attempt to provide flood control. In addition to the cost of the flood control projects, the threat to regional water supplies will jeopardize the future economic growth of Miami-Dade County in areas where such growth has been provided with flood protection and public services. Furthermore, the loss of existing and future agricultural land in the East Everglades will jeopardize the economic diversity and vitality of Miami-Dade County.

(6)

Vegetation, wildlife, and other natural features. The vegetation, wildlife and geologic qualities of the East Everglades make this an area of very high value to Miami-Dade County and the South Florida Region. Nearly fifty (50) types of vegetation communities have been identified, several of which contain unique or rare plant species. Many of the plant species are on State and Federal lists as endangered or threatened. Approximately three hundred fifty (350) animal species are known to occur in the area. A total of thirty (30) wildlife species on the endangered/threatened list occur in the East Everglades, including several of the nation's rarest and most unique animals. Along with Everglades National Park, the East Everglades serves as an important nesting and feeding area for migrating bird species of international significance. Portions of the East Everglades have been designated by the United States Secretary of the Interior as critical habitat for two (2) endangered species, the Cape Sable sparrow and the American crocodile. In addition to the important vegetation and wildlife values, the most significant pinnacle rock formations known to exist in the South Florida region are found in the East Everglades.

(d)

Dangers resulting from uncontrolled development of the area.

(1)

Pollution of groundwater supply. Uncontrolled development within the area poses a serious threat to the quality of water recharged to the Biscayne Aquifer. The placement of septic tanks or sewers at rural residential densities in floodplains and wetlands is expected to create a serious health hazard for present and future residents of Miami-Dade County. Similarly, runoff from developed areas, including streets, is a serious threat to the quality of groundwater. Chemicals and other products such as pesticides, fungicides and fertilizers used in agricultural operations in areas noted as suitable for farming use in the East Everglades pose similar hazards to the surface water supply in the Biscayne Aquifer.

(2)

Pollution of surface water to Everglades National Park. Septic tanks, sewers, suburban runoff and agri-chemical applications outside those areas noted as suitable for farming use in the East Everglades pose similar hazards to the surface water supply of Everglades National Park. Once in the surface water, excess nutrient loads, disease pathogens, heavy metals, PCB's, pesticides and other pollutants generated by development act to reduce diversity and productivity, short-circuiting the natural cycles of life at the base of the food chain. The potential impact on the nursery grounds for Gulf of Mexico and Atlantic fisheries, numerous bird species, and other Everglades fauna is significant.

(3)

Reduction of surface water flow to Everglades National Park. Equally critical to the health of the Park wildlife and fisheries recourses are historic seasonal fluctuations of water levels. The reduction of ground and surface water levels that accompanies residential and inappropriate agricultural development would result in a stress on the Park's existing life systems and begin a process of alteration of the Park biota, generally favoring undesirable exotic species.

(4)

Reduction of groundwater recharge to Biscayne Aquifer. The increase in surface water runoff from impervious cover and reduction in surface and groundwater levels by flood control works that historically have accompanied development of wetlands would pose a serious threat to the groundwater recharge of the Biscayne Aquifer if uncontrolled development is allowed to occur in the area. A reduction in groundwater levels within the area would reduce the water available for drinking and irrigation and would reduce the freshwater head that prevents saltwater encroachment.

(5)

Reduction of flood storage capacity. The creation of compacted roads, parking lots, roofs and ancillary impervious and semi-impervious works, along with any attempts to remove ground or surface water to protect residences or crops would act to impair the historic function of the area as a floodwater retention basin. Removal of water from the East Everglades would cause increases in downstream flood levels. Impairment of surface flow would increase flood stages upstream of the restriction, thereby affecting existing use of upstream lands.

(6)

Danger to development from flooding. Only a very small portion of the East Everglades has flood protection. Residential development in floodplains and wetlands creates public health and nuisance problems. The danger from storm surge in the southern portion of the area is an additional threat to the safety of future residents.

(7)

Danger to development from fire. Periodic fires are a natural and unpreventable part of the East Everglades environment. The area is inaccessible for most fire equipment, and the drainage and exaggerated dry conditions that would accompany development would make fire a serious threat to life and property in the area.

(8)

Loss of vegetation, pinnacle rock, wildlife. Uncontrolled development would irretrievably destroy the pinnacle rock outcrops present in parts of the area. Clearing of vegetation would result in a decrease in native wildlife habitat and has historically facilitated the spread of noxious exotic vegetation species. The loss of habitat would result in further decline in wading bird populations and threaten the survival of two (2) endangered wildlife species.

(9)

Loss of agricultural land. The management plan for the East Everglades identified important existing and future agricultural lands within the study area. Uncontrolled development of these lands will result in the loss of these valuable lands for agriculture, thereby jeopardizing the economic diversity and vitality of the Miami-Dade County economy.

(e)

Advantages to be achieved by development in a coordinated manner. Careful development in a coordinated manner will protect the historic function of the area as an essential source of high quality water to drinking and irrigation wells in South Miami-Dade County and to the Everglades National Park. The area will continue to act as a floodwater retention basin, as a water filter, and as a freshwater head against salt water intrusion into the Biscayne Aquifer. Hazard to human health and safety from coastal flood surge and seasonal flooding can be mitigated. Critical habitats for rare and endangered wildlife species can be protected, as well as other important habitats for native wildlife and plants.

Management of land uses within the area can prevent the imposition of direct and indirect economic, social and environmental cost on private individuals and the public at large by land developers. Property owners in the area will be allowed a reasonable use of their property, making public acquisition unnecessary. However, the use of transferable development rights will be evaluated and, if found to be appropriate, will be applied to all portions of the area as an alternative economic use so that owners may benefit from ownership and leave their land in its natural state.

(f)

Environmental findings. The Board of County Commissioners hereby declares that description and characteristics set forth in subsections (b), (c), (d), and (e) of this section constitute environmental findings and further declares and finds that:

(1)

Protection of the Biscayne Aquifer, its related surface waters and ecosystems, is vital to the continued health, safety and welfare of the present and future residents of Miami-Dade County, Florida.

(2)

The continuing service to the people of Miami-Dade County of the Biscayne Aquifer, its related surface waters and ecosystems, is threatened by uncoordinated development of the area described in this section by:

a.

Decreasing available aquifer recharge area and water quantity;

b.

Degrading the quality of aquifer recharge water;

c.

Decreasing groundwater levels;

d.

Decreasing natural water retention capability;

e.

Decreasing groundwater supply, especially during drought;

f.

Adversely altering surface and subsurface water flows (i.e., quantity, quality and periodicity) to Everglades National Park;

g.

Adversely affecting the contribution of fresh water to adjoining estuarine systems, thereby diminishing their productivity; and

h.

Destruction of vegetation, thereby destroying wildlife habitat.

(3)

The regulation of land use in a coordinated manner within the area of critical environmental concern as described in this section, will minimize the dangers to human health, safety and welfare and to the functioning of the Biscayne Aquifer, its related surface waters and ecosystems, by:

a.

Providing protection against alterations of the natural drainage systems;

b.

Providing protection against coverage of natural water retention and recharge areas with excessive impermeable surfaces;

c.

Providing protection against substantial alteration of the form and function of the natural ecosystem;

d.

Providing protection against deterioration of water quality, both surface and ground;

e.

Providing protection for the continuation of slow, natural overland flow of surface waters into Everglades National Park and the biotic and estuarine communities dependent on such flows;

f.

Providing protection for the biological filtering capabilities of the wetland areas; and

g.

Providing criteria for the method of elevation of structures above the level of seasonal, one hundred-year and storm surge flood levels.

(Ord. No. 81-1, § 1, 1-15-81)