Heather M. Townsend
The purpose of this project is to find out if the oxbows of the Caloosahatchee River have been filling in with sedimentation since the last study in 1978. An oxbow is a meander of a river which has extreme curvature such that only a small island is left between the new river channel and the old river (Webster 1613). The hypothesis states that the Caloosahatchee River oxbows have been filling in with sedimentation and increasing in width since the study in 1978. This study will help to inform the people of Southwest Florida as to whether or not the remains of the Old Caloosahatchee River will survive.
The time between 1978 and 1996 is the focus of the project. This period of time should show that the oxbows of the Caloosahatchee River are either accumulating sedimentation or that they're not collecting sediment.
The total area of each oxbow is being measured in order to determine if as a whole the oxbows are filling in with sedimentation. In each oxbow there are certain cross-sections that are measured. Every 3.048 meters the depth is taken along a select cross-section of the oxbow. Later during the analysis of the project the mean average of every two depths are averaged for each cross-section. Next, all of the averages for the cross-section that are being analyzed are added together and multiplied by ten. This process will eventually determine if any of the oxbows are accumulating sediment. The width is also being measured to find out if the oxbows have become narrower or wider since 1978. The depth by itself will be looked at alone. It is also being measured for a comparison against the 1978 data to determine if they're collecting sediment.
The recent 1996 data was collected in much the same way as the data that was taken on the oxbows in 1978. The results of each year's data was then compared. The project that took place in 1978 was inconclusive as to whether or not sedimentation had formed in the oxbows of the river because the researchers, had nothing to compare their data with. The 1978 data was collected so that the Florida Water Management District could monitor the water flow of the oxbows. The district however did not continue the study (Draft Report- 8758).
There are many things that are questionable about the future study of the oxbows. The main question is: Will anyone do another study about the oxbows in possibly 15 to 20 years, or will the beautiful fragments of the Old Caloosahatchee River be forgotten?
This project was selected because of interest in the Caloosahatchee River. The beauty and environmental impact of the oxbows also played an important role in the selection of this project. The idea of working in the oxbows came from attending the Caloosahatchee River Forum Meetings. It was also inspired by Dr. John Capece, a scientist from the Institute of Food and Agricultural Sciences (IFAS). He is assisting in the project from its beginning to its completion.
The river originally began as a waterfall that at one time fell into the river from its source at Lake Flirt. From there it twisted and meandered all the way to the Gulf of Mexico. For over twenty million years the snakelike Caloosahatchee River slowly flowed with its beautiful clear water through natural vegetation along the river's banks. In 1880, the governor of Florida decided that there needed to be a Southwest Florida Water System. He made a contract with a young rich Philadelphia saw manufacturer named Hamilton Disston. The contract stated that Disston would widen and deepen the Caloosahatchee to eight feet. He also agreed to blast a canal through the marshes connecting the river with Lake Okeechobee.
Hamilton Disston's headquarters for the dredging project was based out of Fort Myers, Florida. The man that Disston hired to supervise the project was Captain J. Fred Menge. Captain Menge came to Fort Myers from New Orleans, Louisiana.
The dredging of the Caloosahatchee began on September 21, 1881. Governor Broward was the first person to begin digging the dredge. This dredge would forever change the path and the future of the Caloosahatchee River. It would be the first of five major dredgings of the river.
When the dredge arrived at Lake Flirt, the source of the river, it plowed right through the shallow five mile length of it causing the small lake to disappear into the path of the new river. In August of 1883, the last piece of land was plowed through to Lake Okeechobee. This changed the beautiful, clear, and winding river into a dark murky one. The reason it changed so drastically was because Lake Okeechobee began to dump large amounts of silt into the river.
On June 25,1910, the Rivers Harbor Act passed giving 121,000 dollars to again deepen and improve the river channel from Punta Rassa to Fort Thompson just east of Fort Denaud. During the last one and a half years of this dredge J. L. Lofton worked on deepening the channel to ten feet from the Gulf of Mexico to Fort Myers. This project wasn't completed until 1913.
The Army Corps of Engineers dredged the river three times. The first time was in 1936, they dredged it to a depth of six feet. The next time was in 1950, and the river was then deepened to eight feet and also straightened from its mouth to Lake Okeechobee. The last dredging began in 1961 and ten years later was completed, in 1971. The purpose of this project was to control flooding in the river. After the final dredging, the river from Moore Haven to the Franklin Lock had an average depth of twenty-five feet and a width of ninety feet. From the Franklin Lock to the Gulf of Mexico the average depth of the river is twenty-two feet, and after the Edison Bridge, the channels width becomes 100 feet across.
There are three locks along the river which were built to control flooding. The first lock, Moore Haven Lock, was finished in 1935, followed by the Ortona Lock which was built in 1937. The last lock built was the W. P. Franklin Lock near Olga which was completed in July of 1964.
Today many people no longer realize that the Caloosahatchee was once a beautiful and winding river. The river is now a channel that is 75 miles in length from its source, Lake Okeechobee, all the way to its mouth, the Gulf of Mexico. Its total drainage is 1378 square miles. The water-type of the river at this time is classified as blackwater. Blackwater is a result of both organic and tannic acids. The sources of the acids are the forests that run along the river's banks and Lake Okeechobee.
The methods to accomplish this project include two people getting into a rowboat and row to the mainland shore where the 1978, researchers collected their data. At that place, hammer one of the stakes into the ground and attach the rope that is flagged to the stake or tie the rope to a strong branch that is on the shore for the zero measurement. String the flagged rope across the oxbow by rowing to the island shore of the oxbow. At that place hammer a stake into the ground or find another strong branch along the shore and attach the other end of the rope to it. Row back to the other shore of the island and on the way measure the depth of the oxbow using the tape measure with a weight on it every 10 feet or every 3.048 meters according to the already marked rope. Every time a measurement is taken call the depth out to the recorder on the boat and that person records the information. If an extra recorder is not available then write down the information. When all of the measurements have been taken across that point of the oxbow take out the stakes that were hammered into both shores or untie the ropes that were tied to branches along the shores. If needed, the stakes will be used again at the next point in the oxbow where the measurements are to be taken. Repeat this procedure at the next given point of the oxbow. When all of the points of the oxbow have been measured, go to the next documented oxbow and repeat this procedure. When all of the measurements have been taken compare them to the already previously taken measurements from 1978.
The oxbows of the Caloosahatchee River each have a unique design, but all have twisting routes. The open oxbows tend to have a lot less vegetation than the closed oxbows. The open ones also appear to have more water flowing through them, where as the closed oxbows appear to be still.
Many of the oxbows, especially the closed ones, have bubbles that rise to the surface because of the decaying sediment. The decaying sediment is sometimes quite deep. It also causes a sulfur smell. These types of conditions are not good for the fish in the oxbows because it deoxygenates the water.
One important thing that was found was that Oxbow #31 was not included in the 1978 draft report of the oxbows. It is assumed that it was lost sometime during the period that it remained in the South Florida Water Management Office. Oxbow #31 was however measured this year but was not included in the report because it could not be compared to previous data.
The purpose of the project was to find out if the oxbows of the Caloosahatchee River have been filling in with sedimentation. The maximum depth of the oxbows has not significantly changed between 1978 and 1996 according to statistical analysis (Figure 1). The width of the different oxbow cross-sections, however, has changed significantly since 1978 according to the data taken and the t test (Figure 2). The oxbows have become wider according to the statistical analysis. The statistical analysis also shows that the areas of the cross-sections in the oxbows have not changed significantly between 1978 and 1996 (Figure 3). See Table 1 for a summary of the statistical analysis.
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The research hypothesis can not be supported for the maximum depth of the oxbows because there were not significant differences. The research hypothesis for the width of the oxbows is supported because there were significant differences. The research hypothesis for the area of the oxbows is not supported because there were not significant differences.
It is believed that erosion has contributed to the increase in the widths of the oxbows. Dredging of oxbows for private use could be one of the explanations for some of the oxbows staying relatively about the same depth. The sedimentation could also get washed out into the main channel of the Caloosahatchee River. The area is probably not significantly different now because determining where the measurements of the 1978 data was taken was difficult, therefore increasing the possibility of taking incorrect cross-section measurements in 1996.
A way to improve the process of studying the oxbows would be to use some type of machine to cut through the floating vegetation in the water. Attempting to paddle through the vegetation was very tiring and time consuming.
Ammann, Pat. "Dredges Gouge Channel From River." The Caloosahatchee 23 Jan. 1972.
Capece, John. Personal Interview. 1995-1996.
Dougherty, Steve. "Clear as Crystal Down to Fort Myers." Fort Myers News-Press 20 May 1975.
Dougherty, Steve. "Dance Halls Churned the Caloosahatchee." Fort Myers News- Press May 1975.
Dougherty, Steve. "River Still an Eye- opener." Fort Myers News- Press May 1975.
Dougherty, Steve. "This River Doesn't Run That Way Anymore." Fort Myers News- Press May 1975.
Dougherty, Steve. "Work Boats." Fort Myers News-Press May 1975.
Douglas, Marjoury Stoneman. The Everglades: River of Grass. New York: Rinehart & Company, Inc., 1947.
Foster, Charles Edgar, And Rae Ann Scholle. Legacy of the Caloosahatchee. Florida: 1995.
Fritz, Florence. Unknown Florida. Florida: University of Miami Press, 1963.
Lane Jr., George. The Rivers of Florida. Florida: Pineapple Press, Inc., 1990.
Lollar, Kevin. " Group Winding Up River Oxbow Study." Fort Myers News-Press 20 Feb. 1996.
Lollar, Kevin. "Teams Study River's Oxbows." Fort Myers News-Press 3 Dec. 1995.
Powell, Eva Kinsey. "Trip Up the Caloosahatchee." Fort Myers News-Press 19 Mar. 1989.
Scholle, RaeAnn. Oxbows of the Caloosahatchee. Florida: 1995.
South Florida Management District. Draft Report-8758 Caloosahatchee Oxbows: Environmental. West Palm Beach: GPO, 1979.
Townsend, Heather. Oxbows of the Caloosahatchee. Florida: 1995.
Water Resources Atlas of Florida. Florida: Institute of Science and Public Affairs, 1985.
Webster's Third New International Dictionary. Massachusetts: Merriam-Webster Inc., 1986.
This page has been accessed
times since
May 28, 1997.
Soil and the Caloosahatchee River
Oxbows - A new paper correlating
soils and land uses near oxbows of the Caloosahatchee River.
Copyright© 1997 by Heather M. Townsend
