Interim Response of Dissolved Oxygen to Reestablished Flow in the Kissimmee River, Florida, U.S.A.

Restoration of the Kissimmee River should have multiple ecological benefits including improved dissolved oxygen (DO) within the river channel. Channelization of the Kissimmee River virtually eliminated flow through the natural river channel. After channelization, chronically low DO concentrations were observed in the stagnant remnant channel. Although no DO data from before channelization exist, reference estimates of pre-channelization conditions were derived from seven relatively unimpacted streams. Stations along the Kissimmee River were sampled for 3 years before construction of the first phase of the restoration project began and for up to 8 years after the completion of construction. After Phase I construction, DO concentrations in the area of the river channel to which flow had been restored increased significantly from 2.2 to 4.9 mg/L, which is similar to DO concentrations observed in the reference streams. Mean DO concentrations for the reference streams ranged from 4.6 to 6.7 mg/L. Comparison of reference data to data from the pre-Phase I and post-Phase I system suggests that channelization had a negative impact on DO and that DO concentrations in the post-Phase I Kissimmee River channel have made a significant recovery. Long-term data trends demonstrate that DO concentrations can be negatively impacted by high flow events and that recovery from these events is generally quick, suggesting some degree of resilience in the system.