Thanks to Gator Man and his long-archived Earthcache at this location for inspiration. This Earthcache has been approved by Paula Bratschi of the US Army Corps Of Engineers.
With an area of 730 square miles, Lake Okeechobee is the largest freshwater lake in the state of Florida. It is the seventh largest freshwater lake in the United States and the second largest freshwater lake contained entirely within the lower 48 states. At its capacity, the lake holds 1 trillion gallons. Depth varies from 1 to 13 feet (0.3 to 4 m).
Lake Okeechobee is thought to have been formed when ocean levels receded about 6,000 years. Originally salty, rainfall eventually changed the lake to fresh water. The lake basin is a concavity in the limestone bedrock of the Florida peninsula. The lake bottom was originally sandy. Much of the western and northwestern shore is still sandy. The eastern and southeastern part of the lake is mostly rock and marl (clays, carbonates, and shell remains). The southern part of the lake is mostly sawgrass peat. The northern and northeastern part of the lake is mostly mud, due to runoff from the Kissimmee River, Taylor Creek, and Nubbin Slough.
The lake is part of Florida's most famous water system: the lakes of the Orlando area drain into the Kissimmee River which flows south to Lake Okeechobee. Other natural sources of waterflow into the lake are Lake Istokpoga, Fisheating Creek, Taylor Creek and Nubbin Slough. As the lake has no natural river connections to the Atlantic Ocean or Gulf Of Mexico, more than two-thirds of the water exited via evapotranspiration (a combination of soil evaporation and plant transpiration) with the remainder being absorbed by the porous lake bottom or flowing into the vast marsh of the Everglades via distributaries, littoral marshes, and naturally-occurring flooding. This sheet flow from Lake Okeechobee to Florida Bay is nicknamed the River Of Grass. This flow was heavily altered during the 1900s. Numerous canals now run southeast from the lake to the Atlantic Ocean between Palm Beach and Miami. Other canals connect to the Caloosahatchee River in the west and the St Lucie River in the east. The lake's water level is controlled by water control structures connecting these canals to the lake, allowing for releases in periods of higher water levels (although nothing can be done to raise the lake's level during periods of severe drought). This has affected not deprived essential water from the Everglades, but also impacted both the Caloosahatchee and St Lucie Rivers: decreased salinity levels, severe decrease in water clarity, and alteration of the depth and makeup of the river bottom. These effects have had significant impact on the animal and plant life in those rivers.
The most famous alteration to Lake Okeechobee are not the canals that drain it and divert its waterflow, but the Herbert Hoover Dike that encircles it. The Hoover Dike was built in the 1930s after devastating hurricane-induced flooding in 1926 and 1928 and further improved in the 1960s. The dike keeps the lake from overflowing, but as the flooding is naturally occurring this impacts the nutrients in the soil around the lake and prevents water from flowing into the Everglades. The construction of the dike also vastly altered the lake's natural shoreline, both in appearance and location. Early visitors to the Lake in the 1880s noted that "the border line of the lake is in most places not absolutely defined owing to a continuous passage of the open waters into those of the Everglades."
The lake suffers from pollution issues mostly as a result of farm runoff, especially arsenic and phosphorous.
The current lake is can be divided it into three distinct zones: the littoral zone, the nearshore zone, and the pelagic zone. These zones vary along with the water levels of the lake. The littoral zone is mostly located along the western edge and around the islands in the southern part of the lake, covering a vastly smaller area than it did before the Hoover Dike was built. These marshy areas are the shallowest parts of the lake. The nearshore zone is adjacent to the littoral zone. Deeper than the littoral, this zone is most heavily affected by high water level in the lake. The pelagic zone is the deepest part of the lake, located mostly near its middle. This zone has a much higher turbidity and nutrition content than the rest of the lake. During periods of low water levels, this zone is unable to mix with the other two zones.
Required Tasks
To get credit for this Earthcache, you will need to answer some questions. Please send me the answers to the following questions to complete this Earthcache. Do not post answers or spoiler photos in your log. Failure to send answers to these questions is grounds for deletion of your log.
There are 4 flood gates that can be raised to release water from Lake Okeechobee. Each gate has a gauge (in feet) marked on the wall next to it.
1. According to their gauges, to what height are the gates currently open?
Walk down the Hoover Dike to the shore of the lake. Between the rocks (placed to decrease erosion) and the water there is a beach of sorts, but this beach is not made of the material you might expect.
2. What is the beach made of? Hint: not sand or mud.
Drive over to the kiosk about the Lake Okeechobee Scenic Trail (LOST). This trail encircles the lake, mostly atop the Hoover Dike. Thus the circumference of the lake will be a little smaller than the length of the trail.
3. According to the sign, how high is the Hoover Dike and how long is the trail?
Drive over to the trailhead for the Raphael Sanchez Trail. You do not need to hike the trail to complete this Earthcache, but doing so is encouraged.
4. According to the trailhead sign, what is the significance of this trail in regards to Lake Okeechobee?
(This is NOT anything to do with the person who donated the land for the trail.)
Optional Tasks
5) Post a picture of you and your GPS with the large Port Mayaca bridge in the background.
6) If you visit here near the end of the day, take a photo of the sunset over the lake and post it to your log.
