The Story of St. Joe Bay – Apalachicola Bay Watershed
Over seventy five years ago the Army Corp of Engineers, with help from our more industrial minded forefathers, connected the saltwater environments of St. Joe Bay and East Bay to the freshwater ecosystems of Lake Wimico via the Inter-coastal waterway (ICW) and the Gulf County Industrial Canal. Lake Wimico and its surrounding wetlands and tributaries are a major source of freshwater for the Apalachicola Bay ecosystem, and they collect, store, filter and feed this freshwater into the Apalachicola Bay ecosystem via the Jackson River.
This direct connection of a once pristine, zero flow, freshwater drainage basin ecosystem with the saline environments of St. Joe Bay and East Bay is now causing catastrophic damage to the Lake Wimico watershed and the Apalachicola River system, its marshes and Apalachicola Bay. The reverse is also happening, with High river flow causing unrestrained runoff into St Joe Bay, resulting in extreme sedimentation of the entire bay floor and increased turbidity causing damage to seagrass beds and the marine life that depends on them.
Core Samples From St. Joe Bay Floor
Jim Woodruff Dam Construction
Since the construction of Jim Woodruff Dam the Corp has maintained navigational depth (approx. 9 ft at Blountstown) in the Apalachicola River. As long as the flow rate was adequate to maintain these depths the effect of salinization were minimal.
These river levels maintained enough freshwater in the Lake Wimico drainage basin and the Apalachicola River Marsh to keep the saltwater from St. Joe Bay largely pushed back. Since 1988, however, the Corp has no longer consistently managed navigational depth in the Apalachicola River. (See the attached information paper from the Corp) This has resulted in longer and more drastic low flow periods, especially in the summer months. This extreme low river flow creates a gradient (especially in high tide events, tropical weather systems, and sustained west winds) that allows salt water from St. Joe Bay and East Bay to enter the ICW, into Lake Wimico, through the Jackson River, into the Apalachicola River and into the Apalachicola river marsh and Apalachicola Bay.
Reverse Runoff Effects
The reverse is also happening. During periods of high river flow (usually during the winter and spring) the nutrient and sediment rich waters of the Apalachicola floodplain are back flowing into St Joe Bay and depositing the rich sediment that is so desperately needed by the oysters in Apalachicola Bay, but is catastrophic to sea grass health in St. Joe Bay. Control of storm water runoff has been a critical and valuable asset to improving coastal water quality nationwide, yet here in St. Joe Bay we have a massive, uncontrolled, man-made runoff occurring every time there is high river flow! The World Resources Institute has documented eutrophication and Hypoxia in St. Joe Bay since the 1990’s. St. Joe Bay is one of the few completely Saltwater Bays in Florida. Unlike the majority of our Bays that are formed by rivers or creeks running through them to reach the Gulf or Atlantic, St. Joe Bay never had any freshwater effluent running into it until we connected St. Joe Bay with the Apalachicola River floodplain through the ICW and the Gulf County Industrial Canal. Over the years this uncontrolled runoff has deposited over FIVE FEET of river sedimentation on to the floor of St Joe Bay in many areas. (See photos of core samples from the floor of St. Joe bay )
Flow & Sediment Calculations
Our calculations show over 5 BILLION GALLONS of freshwater are being dumped into St. Joe Bay every 24 hours with a 20 ft river reading at Blountstown. Flow is easy to calculate, Sediment is a very difficult thing to quantify. Using Data from the US department of the interior for Dam construction, and other sediment numbers derived from flood events on the Mississippi River shows up to ONE HUNDRED THOUSAND TONS of sediment could be dumped into St. Joe Bay each 24 hour period at this river reading! Imagine TEN THOUSAND DUMP TRUCKS lined up each day to dump their loads into St. Joe Bay! Every gallon of this valuable fresh water and ton of this nutrient rich silt belongs in Apalachicola Bay, NOT St. Joe Bay. Our calculations show that between 10% to 12% of TOTAL RIVER FLOW is being lost from Apalachicola Bay into St. Joe Bay at this river reading! We also know that local rainfall contributes a lot of water to our watershed. One inch of rain on one acre of land produces around 27000 gallons of water. Multiply this by 75000 (the number of acres in the Wimico Drainage Basin) and you get roughly 2 Billion gallons for every inch of rain in the Wimico watershed. Apalachicola Bay is supposed to get EVERY DROP of this water. If the River is at 5 ft and it’s low tide in St. Joe Bay, how much water is Apalachicola Bay losing? We contend that much of this precious water is becoming runoff into St. Joe Bay. While these calculations are important, it is essential to remember that the control number, the number it USED TO BE, is ZERO! There should be ZERO gallons of freshwater and ZERO tons of sediment leaving the Apalachicola River Floodplain, and ZERO gallons of freshwater and ZERO tons of sediment entering ST. Joe Bay from the Apalachicola River floodplain.