The 2020 State of the River Report points to some positive developments in the health of the St. Johns River, but also highlights several concerning trends.
The 13th State of the Lower St. Johns River Report finds that contamination by metals, pesticides and industrial products and chemicals is a serious concern. Concentrations of arsenic, cadmium, lead, nickel and silver have been increasing in the mainstream of the river since 2016. Stormwater run-off from roads, residential and commercial development and agriculture are also adding nutrient pollution to the river.
Pollution from these sources pose a threat to human health, the economy and the ecosystems that support plants and animals. “Water quality in some of the tributaries is too poor to allow the safe consumption of fish from these streams or to allow swimming,” the report reads.
However, the report says overall water quality is improving in the St. Johns River, largely due to local governments and partnering state agencies undertaking projects to reduce the flow of pollutants into waterways, such as replacing failing septic tanks and improving wastewater treatment plants.
Despite these positive trends in water quality – such as total nitrogen levels improving – harmful algal blooms (cyanobacteria) were widely reported throughout the summer of 2019.
Another concerning trend the report points to is increased salinity, despite recent storms that have added freshwater to the river system. Additionally, the amount of submerged aquatic vegetation is on the decline in several regions in the basin and is now below levels desired to support fisheries, prevent erosion and provide flood protection.
Increased salinity and decreases in submerged aquatic vegetation are being driven by a variety of factors, including sea level rise, and conditions are expected to worsen in the northern parts of the river basin due to the dredging project. The Army Corps of Engineers has also acknowledged that deepening the St. Johns River by 7 feet could lead to water levels increasing by several inches in the mainstream of the river during a 100-year storm surge.
Loss of wetlands, which will likely lead to increased flooding from storm surge and sea level rise, is another troubling development, according to the report. Wetland ecosystems along the St. Johns are being threatened by urban development, agriculture, pollution, run-off and invasive species — the number of which has risen to 90. Non-native species, like Asian Clams, blue-green algae and hydrilla, threaten the local economy in addition to wetlands and other ecological systems.
On a positive note, with 85 sanitary sewer overflows and a total of 959,267 gallons released, 2019 was an improvement…