A recent water drawdown at Stormwater Treatment Area 1 West in South Florida exposed a larger than expected population of invasive armored catfish, signaling that current control efforts are falling short. The event occurred when the area was deliberately drained for maintenance, leaving fish concentrated in shallow pools where biologists could survey them.

The Florida Everglades functions as a slow-moving river that filters water for much of the state. Stormwater treatment areas, which cover roughly 57,000 acres, are man-made wetlands designed to clean water before it enters Everglades National Park. Periodic drawdowns are part of ongoing restoration work, allowing crews to maintain the areas and assess their condition.

When the water at Treatment Area 1 West was lowered, biologists found thousands of armored catfish, an invasive species with hard bony plates that protect them from predators. The catfish dig burrows into the banks of the wetlands, and with the water gone, those burrows were clearly visible, damaging the natural structure of the swamp and making it harder for native plants to grow. The fish can survive briefly out of water, so many were still alive when the survey crews arrived.

The findings indicated that control measures have not kept pace with the spread of the species. For the team involved, it was one of the clearest indications in recent years that the invasive population is larger than previously estimated.

The broader context dates back more than a century. In the 1880s, developer Hamilton Disston attempted to drain the Everglades for agriculture, moving large volumes of water out of the Kissimmee River Basin. In 1948, the federal government launched the Central and Southern Florida Project, a large network of canals and pumps intended to control flooding and supply water. That project ultimately destroyed more than half of the original wetlands.

Because the region has been drained and filled for over a hundred years, wildlife has adapted in ways that complicate restoration. The mud at the bottom of drained wetlands contains both ecological history and chemicals such as phosphorus from older agricultural operations. Each drawdown offers researchers a view of the accumulated effects of those past decisions.

The presence of armored catfish burrows suggests that simply restoring water flow will not be enough. Knowing what lives in the mud is necessary to manage the ecosystem effectively. Given the scale of the drainage infrastructure, even minor errors can disrupt habitat for thousands of animals.

Burmese pythons have also been found in exposed burrows during drawdowns in other areas, including the Picayune Strand restoration project. These snakes, which can reach lengths of 20 feet, typically hide in thick grass or underwater. Low-water conditions revealed their dens, allowing removal teams to capture them more easily than during normal conditions.

The python population has contributed to a significant decline in small mammals such as rabbits and raccoons, which disrupts the broader food chain. The drawdowns demonstrated that pythons are not only moving through the water but also inhabiting burrows beneath the surface.

Low-water conditions also concentrated predators in deeper holes, a phenomenon researchers refer to as a predator pit. Large numbers of alligators gathered in these areas, along with wading birds such as wood storks and great egrets, feeding on trapped fish. These periods provide researchers with unusual observation opportunities.

The chemistry of drained wetlands also presents challenges. Exposing soil to air can release phosphorus, which originates in fertilizer used on agricultural land. When phosphorus enters the water, it can fuel blooms of blue-green algae downstream, including in the Caloosahatchee River. These blooms can produce toxins and reduce oxygen levels in the water, leading to fish kills.

A similar issue occurred in 2021 at Piney Point, where more than 215 million gallons of contaminated water were released to prevent flooding. The nutrient-rich water contributed to a red tide that lasted for months. Surveys after the water receded found large areas of dead shellfish and contaminated sediment.

Invasive apple snails have also spread further into protected areas than previously known. During a drawdown, researchers found large numbers of their egg clusters on dead plant stems. These snails can carry rat lungworm, a parasite that poses a risk to humans.

Despite these findings, there have been positive developments. In 2023, researchers reported that several key restoration sites were beginning to recover. Controlled drawdowns, which mimic natural dry seasons, helped reduce invasive plant cover by about 40 percent. Native plants returned on their own from seeds already present in the soil, without requiring replanting.

Small native species such as crayfish and grass shrimp also reappeared. These organisms form the base of the food web, and their return supports birds, alligators, and larger predators.

Data from drawdowns is now being used to map where invasive species such as pythons and walking catfish are likely to be found at low water levels. Researchers are also working on ways to manage water movement that avoid triggering fish kills during routine maintenance. The restoration effort is expensive and requires sustained political support, but recent results indicate measurable progress.

Each drawdown provides a direct look at the current condition of the Everglades. The information gained helps researchers understand what is living below the surface and adjust management strategies accordingly. The work continues under difficult field conditions, but the data collected is shaping the next phase of restoration.