Like shooting stars zooming across the night sky, fireworks instill a sense of wonder and excitement. Their bold colors and expressive shapes illuminate our summers in backyards, small towns, and big cities all across America. This July, our country's 250th anniversary led to bigger, bolder shows that broke global records. Once the show is over and the smoke clears, however, the damage these spectacles cause to our environment, particularly our waterways, becomes clear.

Pyrotechnic formulations rely on a variety of chemical compounds to produce their dazzling color and visual effects. Manufacturers mix metals such as barium, strontium, copper, aluminum, magnesium, and titanium, alongside oxidizers such as perchlorates to help sustain combustion. When one considers that beyond the metals and oxidizers, each firework's bang creates a slew of physical debris, including paper, cardboard, plastic, and shell fragments, and it's easy to see how these could cause environmental harm. These by-products have to land somewhere, and often accumulate in rivers, lakes, estuaries, and coastal environments. 

Wildlife can also experience the effects of fireworks. Loud explosions and bright flashes may disrupt nesting birds, fish, amphibians, and other aquatic species during sensitive breeding and feeding periods. Debris left behind can pose entanglement or ingestion hazards for wildlife, while shoreline litter may eventually break down into smaller plastic fragments that are more difficult to remove.

Studies have documented short-term increases in concentrations of some metals and perchlorate in surface waters following large fireworks displays. In 2019's "Perchlorate behavior in the context of black carbon and metal cogeneration following fireworks emission at Oak Lake, Nebraska.", Kumar, M., Snow, D.D., Li, Y., & Shea, P. evaluated perchlorate together with firework-associated metals, demonstrating deposition of both following fireworks displays. A 2016 U.S. Geological Survey study, "Perchlorate and Selected Metals in Water and Soil within Mount Rushmore National Memorial, 2011-15", demonstrated elevated perchlorate persisted in groundwater and surface water years after fireworks ended. 

While these elevated levels often decline through dilution, dispersion, or natural processes, repeated events or displays over smaller water bodies may prolong exposure and contribute to localized changes in water chemistry. Aquatic ecosystems may also be affected through physical disturbance and habitat contamination. Firework debris can settle into benthic habitats, where it may be incorporated into sediments or ingested by aquatic organisms. The intense noise and pressure waves generated by aerial fireworks have been shown to alter the behavior of birds, fish, and other wildlife, disrupting feeding, nesting, migration, and spawning activities. Species already experiencing environmental stress may be particularly vulnerable to these disturbances during critical life stages.

Environmental monitoring plays an important role in understanding the cumulative effects of fireworks on aquatic systems. Water quality sampling before and after major events, sediment analysis, and biological assessments provide valuable data to evaluate changes in contaminant levels and ecosystem health. These scientific observations can help communities balance public celebrations with effective environmental stewardship by informing decisions on display locations, cleanup practices, and long-term resource management.