Lighthouse Beach Park on Aug. 7, 2024. View more aerial imagery of the lighthouse.

The Caloosahatchee River and Estuary (CRE) is a delicate ecosystem composed of a diverse array of habitats and endemic species. The watershed has faced substantial water quality issues since manmade alterations to the system began in the 1880s. Learn more in our water quality FAQ >>

Historically, the Caloosahatchee River did not connect to Lake Okeechobee, but since the two were artificially linked, the lake’s water quality issues also impact Southwest Florida’s environment and the Gulf of Mexico.

Much attention is paid to the impact releases from Lake Okeechobee have on the CRE, however, basin runoff from the Caloosahatchee watershed also takes a considerable toll.

A recent study from SCCF’s Marine Lab found that both Lake Okeechobee releases, as well as runoff from the surrounding land area, have significant negative impacts on downstream water quality. This study demonstrated that while restoring the Everglades and sending water south is critical to the health of our estuaries, we must also find solutions to store and treat water within the Caloosahatchee watershed.

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Watershed Runoff

Runoff from the Caloosahatchee watershed is often highly polluted, carrying excess nutrients from fertilizers, chemicals, pet waste, insecticides, and other pollutants as it flows into storm drains or directly into waterways during rain events.

Failing septic systems, growing increasingly vulnerable to leakage from raising groundwater levels, present another large source of pollution to local waters. These nutrient sources are exacerbated by extensive wetland loss throughout the watershed that otherwise could have provided some filtration to polluted water before it entered the river. These compounding factors enhance the conditions that can allow algae blooms to rapidly intensify to harmful sizes.

Due to Southwest Florida’s high levels of precipitation, especially in the summer months, watershed runoff represents a frequent stressor to the CRE system, depositing nutrients and decreasing water quality whenever runoff occurs.

Lake Okeechobee Releases

Lake releases represent a more discrete stressor to this system, delivering nutrients quickly and in large concentrations. If watershed runoff can be thought of as a constant stream of water slowly eroding a riverbed, lake releases would represent a flash flood. While the flood has an instant and apparent impact on the area, the steady erosion over time is also hugely influential. 

The volume of freshwater entering the estuary during lake releases is so large that even without pollution it would still cause harm to the estuary and its organisms by drastically changing the salinity gradient.

Because watershed runoff is relatively constant in summer months, and lake releases are episodic, lake releases occurring during the wet season can deliver a damaging blow to an already weakened system. Over time, these compounding issues decrease the ecosystem’s resiliency.

Lake releases deliver a higher volume of nutrient-laden water at once and the impacts are immediately visible, while watershed runoff represents a more constant driver of overall poor water quality in the CRE.

Fixing Water Quality Issues

While the impacts of lake releases and watershed runoff both deliver significant harm to the Caloosahatchee, comparison remains difficult due to their vastly different characteristics. This means these two problems also require different mitigation strategies.

According to SCCF’s recent study, overall nutrient concentrations in the CRE were strongly related to watershed inputs due to their persistent nature of delivery from June through October. Based on this, it’s essential to acknowledge the downstream impacts of watershed runoff when advocating for healthy water quality and to recognize its reduction as a key solution to ongoing water quality issues in Southwest Florida.

Key solutions for reducing harmful Lake Okeechobee discharges include completing Everglades restoration projects and reducing nutrient levels in Lake Okeechobee. In order to reduce watershed pollution, it will be necessary to implement best management practices for fertilizer use, preserve our wetlands that remain intact, reduce large-scale development in fragile ecosystems, identify nutrient hotspots for targeted reduction, and plan more storage and treatment opportunities along the Caloosahatchee. 

Advancing solutions that reduce threats from both watershed runoff and Lake Okeechobee discharges will provide the greatest protection to Southwest Florida’s coastal ecosystems and the people and wildlife calling them home.

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