Lake Okeechobee is just outside the CHNEP area; however, its management and water quality have a direct and significant impact on the ecological health of the Caloosahatchee River, its estuary, and watershed. The man-made dike surrounding the lake provides necessary flood protection to area residents, and the Lake's water levels are controlled by a series of water control structures to its west, east and south. However, these artificial elements and the Lake's operations have caused unintended negative consequences for the ecological health of the Kissimmee River basin and the Everglades, as well as for the St. Lucie and Caloosahatchee Rivers and their estuaries. The lake is polluted with excessive nutrients and pesticides and as a result, experiences periodic cyanobacteria algae blooms. High water levels in the lake cause concern that the dike may breach, endangering public health and safety. Additionally, high Lake levels for sustained periods can cause the Lake's submerged aquatic vegetation to die off, resulting in decreased aquatic habitat and poorer water quality.

The Caloosahatchee River and its estuary require regular, adequate and appropriate levels of freshwater flow from the Lake to maintain proper salinity in its tidal reach for maintaining conditions for its aquatic life. Therefore, proper management of Lake discharges is imperative for maintaining an ecologically healthy Caloosahatchee River and Estuary. Lake Management and controlling the timing and amount of discharges from the Lake is a delicate balancing act that must consider public safety, the health of the lake, and the health of the estuaries. Too much freshwater flow lowers salinity excessively in the estuaries and overwhelms them with pollutants from the lake. Too little flow, and the estuaries suffer harm from low water levels and high salinity. Detailed information about the release schedule is documented in the Lake Okeechobee System Operating Manual (LOSOM).

The South Florida Water Management District (SFWMD) upgraded the reference system used to measure water elevation readings from the National Geodetic Vertical Datum of 1929 (NGVD 29) to the North American Vertical Datum of 1988 (NAVD 88). The upgrade provides the public and stakeholders with more scientifically accurate information about levels for waterbodies in our region. While there is no difference in the actual water level, the water level readings in the NAVD88 measurement system will read about 0.6 feet to 1.6 feet less than the readings in the older NGVD29 measurement system. Visit SFWMD.gov/NAVD for more information