Northwest Florida Water Management District

Transcription

1 Looking at Northwest Florida Water Management District

2 The Northwest Florida Water Management District and SWIM

3 About the St. Marks Watershed When it rains in the Tallahassee area, water runs from the paved streets and red clay hills, down the Cody Scarp, to the Woodville Karst Plain. A watershed, or drainage basin, drains water to a common point in this case, the St. Marks River. The St. Marks watershed covers 1,170 square miles from the hills of Monticello to the Apalachee Bay. The northern portion of the St. Marks watershed includes hardwood/cypress river swamps and several lakes in and near Tallahassee, such as Lafayette, Munson and the Bradford Brook Chain of Lakes, as well as the more rural Miccosukee. Much of the southern portion of the St. Marks watershed is distinguished by its karst topography, in this area known as the Woodville Karst Plain. A karst plain is a porous landform, with conduits dissolved in limestone, and is thinly-covered in a low sand hill veneer. The many conduits, or solution features, of a karst plain quickly absorb water and funnel it along cracks and tunnels in the limestone. Solution features of karst plains include sinkholes, sinkhole lakes, disappearing rivers, springs and caverns. These features are created over millions of years as slightly acidic rainwater percolates downward and dissolves limestone, gradually increasing openings. Large tunnel-like caverns may result and are often filled with water. Notable karst features in the St. Marks watershed include Wakulla Springs, Spring Creek, Leon Sinks, River Sinks and Natural Bridge where the St. Marks River is swallowed to re-emerge a short distance later. Wakulla Springs is a first magnitude spring. It pours forth an average 2,900 gallons per second from a vent 140 feet deep. Divers have mapped 16 caves, some with rooms 45 feet high and 120 feet wide and some 1,800 feet long. Karst Topography In many areas of Leon, Jefferson and Wakulla counties, limestone is at or near the land surface and, as a result, the Floridan Aquifer may be recharged quickly. Recharge is the process by which water is added to the aquifer by seeping through the overlying soils. Rain water percolates into the aquifer and can easily become contaminated by nonpoint pollution as well as by careless dumping of oil, gas, household and industrial wastes.

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5 One of the most effective methods of protecting water quality has been the public purchase of natural lands. Public conservation areas in the St. Marks watershed currently include the Apalachicola National Forest, St. Marks National Wildlife Refuge and Wakulla Springs State Park. The Floridan Aquifer is the source of drinking water for most of northwest Florida. Ninety percent of the water we drink in Florida comes from the ground. Generally the water supply in the St. Marks area has been plentiful and of high quality, requiring little treatment for public use. The concern is that pollution from point and One gallon of gasoline spilled nonpoint sources will impact water supplies in the carelessly can contaminate a area, as well as the ecology of surface waters million gallons of water! downstream of the spring discharge. Because limestone lies so close to the surface in this area, surface water moves quickly into the Floridan Aquifer. Once water reaches the aquifer, potential for filtration, absorption and biological removal of contaminants is limited. Nonpoint source pollution is primarily carried by stormwater runoff. Impurities and contaminants can come from fertilizer, pesticides or chemicals used by households. They include sediments from construction sites or other cleared areas and spills from service stations. Point source pollution is discharged from a single, identifiable source, such as an industrial or sewage treatment plant. Contaminants from both point and nonpoint sources can harm fish and other organisms, degrade natural habitats and reduce the water s quality. Threatened and Endangered Species in the St. Marks Watershed Plants: southern milkweed, scare-weed, Flyr s brickell-bush, Godfrey s privet, Washington thorn, poppy mallow, spoon-leaved sundew, trout lily, heartleaf, wiregrass gentian, mountain laurel, Florida anise, corkwood, Godfrey s blazing star, panhandle lily, hummingbird flower, Ashe s magnolia, pyramidal magnolia, green adder s mouth, Indian cucumberroot, narrowleaf naiad, Chapman s butterwort, bent golden aster, yellow fringeless orchid, wild coco, white-flowered wild petunia, gopherwood buckthorn, mock pennyroyal, Mexican tear-thumb, Alabama rhododendron, orange azalea, Chapman s rhododendron, chaffseed, karst pond xyris, Miccosukee gooseberry, Florida willow, variable leaved Indian plantain Reptiles: Kemp s ridley turtle, American alligator, eastern indigo snake, loggerhead turtle, green turtle, leatherback turtle Fish: Gulf sturgeon Invertebrates: purple bankclimber, Ochlockonee moccasinshell, oval pigtoe, shiny-rayed pocketbook Birds: piping plover, peregrine falcon, southeastern American kestrel, bald eagle, wood stork, red-cockaded woodpecker, least tern Mammals: gray bat, manatee, Florida black bear The many plants, animals and habitats within the St. Marks watershed and surface waters are natural treasures that are all too sensitive to human impacts. Preservation and protection of this valuable heritage cannot be measured in dollars. Risk to the Florida environment is extreme. Nonetheless, parts of Florida, including the St. Marks watershed, still have large natural areas that support critical species, such as black bear, woodstork, red-cockaded woodpecker and manatee. Our conservation efforts are of global importance. Senator Bob Graham

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