The National Park Service has denied South Dakota's request for fireworks at Mount Rushmore for the Fourth of July/Kurt Repanshek file

National Park Service officials have again denied a request from South Dakota to allow a fireworks display over Mount Rushmore National Memorial to celebrate the Fourth of July.

While the agency under the Trump administration allowed the display in 2020, the Biden administration turned it down for last year and remained steadfast this year, citing objections from tribes that see the display as posing "an adverse effect to the traditional cultural landscape."

The denial, signed by Mount Rushmore Superintendent Michelle Wheatley, also noted that firework displays can adversely impact the environment, could spark wildfires, interfere with cultural and historical presentations at the memorial for the holiday weekend, affect concessionaire operations, create a public danger due to the gathering of a large group that couldn't safely be evacuated from the memorial in the event of a wildfire, and conflict with a "patriotic Independence Day celebration" the Park Service is planning.

In her letter, the superintendent also noted that a March 2021 wildfire at Mount Rushmore was the largest in the memorial's history and forced a three-day closure of the site.

"Current drought conditions and the 2022 wildfire outlook indicate the fireworks would cause a high likelihood of wildfire ignition," wrote Wheatley in her March 14 letter.

South Dakota Governor Kristi Noem sued Interior Secretary Deb Haaland after the Park Service turned down her request to resume the fireworks in 2021. While the 8th U.S. Circuit Court of Appeals declined to issue a temporary injunction to allow the display, the case remains pending in the court.

A 2016 study by the U.S. Geological Survey concluded that surface and groundwater at Mount Rushmore were probably polluted with a chemical common to rocket fuels and explosives by past fireworks' displays. The environmental assessment prepared for  the 2020 event played down the threat of additional perchlorate contamination by noting the U.S. Environmental Protection Agency had been considering a move to bump up the allowable amount of the chemical in drinking water by more than three times, from 15 microgrms per liter to 56 micrograms per liter.

Perchlorate has been found to interfere with the function of the human thyroid gland.

Aerial fireworks displays took place at the memorial around the 1998-2009 Independence Days. The USGS and National Park Service studied perchlorate and metals associated with fireworks in 106 water and 11 soil samples taken from Mount Rushmore during 2011-2015. Perchlorate concentrations were greatest in samples collected from the northeast side of the memorial, and the scientists found perchlorate in soil where the fireworks were launched and where the debris landed.

That testing found a maximum perchlorate concentration of 54 micrograms per liter measured in a stream sample, and 38 micrograms per liter measured from a groundwater well. In contrast, all groundwater and stream samples collected from sites outside the memorial boundary had perchlorate concentrations less than 0.2 micrograms per liter.