Dissolved Oxygen in the Kissimmee River: Baseline Condition and Initial
Response to Restoration
David J. Colangelo, South Florida Water Management District, Kissimmee
Dept., West Palm Beach FL
Channelization of the Kissimmee River transformed the flowing river into a
central drainage canal (C-38) with a series of reservoir-like pools. Flows through
remnant river channels were eliminated allowing aquatic vegetation to encroach
upon open water areas and oxygen-depleting organic sediments to accumulate
over the river’s sandy substrate. The 9-m deep canal also drained the adjacent
floodplain, thereby reducing the ratio of surface area to volume of water and
limiting the ability of the system to be re-aerated through wind and flow-induced
mixing. Dissolved oxygen (DO) has been identified as an important component
for evaluating success of the Kissimmee River Restoration project because it is
essential to the metabolism of most aquatic organisms and it is easily measured.
Pre-restoration DO data were collected at stations within the river channel
between March 1996 - June 1999. Mean DO concentrations were consistently
low (< 4 mg/L) at all stations during this baseline period; however, dry season
concentrations were slightly higher than wet season concentrations. A clinograde
oxygen profile and thermal stratification during the wet season also were
observed.
Restoration of continuous, variable flow through reconnected river channels is
expected to flush flocculent organic sediments and increase DO concentrations by
reducing biochemical and sediment oxygen demand and increasing atmospheric
aeration. Continuous flow should restrict/preclude mid-channel growth of aquatic
macrophytes and reduce the potential for deposition of organic matter over midchannel substrates. Initial post-construction (February 2001 - present) response of
DO will be presented. Changes in river channel water column community
metabolism due to restoration also will be discussed.
David J. Colangelo, South Florida Water Management District, 3301 Gun Club
Rd., West Palm Beach FL, 33406, Phone: 561-682-2843, Fax: 561-682-0100