Myakka River Basin -- Hydrologic/Water Quality Assessment

SWET completed this project for the USEPA.The Myakka River is a diverse dark water river approximately 60 miles in length just off the gulf coast of southwest Florida. Due to strong citizen interest in preservation of its pristine nature and scenic qualities, the Myakka was declared a 'Wild and Scenic River' by the Florida State Legislature in 1985. The eastward development fringes of Venice and other coastal cities in the region are increasing their adverse impact on the lower reaches of the river. The middle and upper subbasins have a significant amount of mining and agricultural activities including phosphate mining, cattle, citrus, and vegetables. The Myakka River State Park encompasses a significant portion of the middle section of the river basin including the Upper and Lower Myakka Lakes.

The USEPA, in cooperation with various state and local agencies and interest groups, is in the process of developing Total Maximum Daily Loads (TMDLs) for various listed reaches within the Myakka River Basin. The TMDL process has three important aspects: first, determine and set the appropriate TMDLs for the listed reaches; second, to develop specific abatement plans for achieving the TMDL; and finally, to implement and monitor the plans that will reduce non-point source pollution loads.

To assist EPA in these efforts, WAM was applied to the watershed. The model assisted in: (1) assessing and evaluating environmental impacts resulting from point and non-point source runoff; (2) developing management strategies for controlling runoff, pollution loading, and associated environmental problems; and (3) evaluating environmental impacts resulting from proposed management strategies. For this project, WAM was enhanced to simulate biological oxygen demand (BOD) as well as water control structures (culverts and weirs) found in the basin. The simulated values provided a good representation of observed data.