Graduation Year


Document Type




Degree Name

MS in Civil Engineering (M.S.C.E.)

Degree Granting Department


Major Professor

Sarina Ergas, Ph.D.

Co-Major Professor

Mahmood Nachabe, Ph.D.

Committee Member

Elizabeth (Betsey) Boughton, Ph.D.


Agriculture, Best Management Practices, Lake Okeechobee, Streamflow Trends, Water Quality


Despite efforts to improve water quality within the watershed since the 1970s, harmful algal blooms (HABs) still occur within Lake Okeechobee (LO). HABs are harmful to the people, the ecosystem, and the economy dependent on the lake. Taylor Creek Nubbins Slough (TCNS) is a subwatershed of the lake, contributing to a large percentage of the nutrient loading. Due to the size and complexity of LO’s watershed, two smaller basins within the TCNS subwatershed were selected to evaluate the following research questions: (1) How do water quality trends contrast between two basins? (2) How do nutrient load and treatment within the basin affect the water quality trends in the last three decades?

Annualized total nitrogen (TN) and total phosphorus (TP) trends for the two subbasins were compared using the United States Geological Survey’s R-studio package Exploration and Graphics for RivEr Trends. The impact of nutrient management (loading and treatment) on the water quality trends were investigated with multiple approaches (1) TN and TP seasonality, (2) nitrogen speciation, (3) wastewater treatment facility permits, (4) best management practice (BMP) enrollment, and (5) estimated TN and TP loading based on land use.

Annualized trends between the basins differed more than expected. Estimated TN and TP loading were similar between the two basins, and there were not enough details on treatment and practices to attribute changes in treatment to the annualized trend. However, two results were identified that may impact the difference between water quality trends in the two basins (1) the seasonality between the speciation of TN and (2) the coupling of annualized TN and TP trends within the basins.