Editor's note: The following is an unedited release from the National Park Service.

Members of the U.S. Army Corps of Engineers have been working this week to remove hazardous debris and improve fish passage conditions at Elwha and Glines Canyon dam sites in and near Olympic National Park in Washington state.

Remnants of the Elwha Dam's foundation remain at the former dam site and include long pieces of rebar and other metal shards that pose a safety risk to boaters, as well as portions of the concrete foundation. Boaters have been advised to avoid this area of river since May of this year.

Experts from the USACE visited the Elwha Dam site in late July and gathered information about the type and location of debris. About 25 pieces of debris, primarily one- to three-foot-long pieces of twisted rebar were identified and mapped. This week, USACE divers have been using an underwater cutting torch to remove the metal debris. The divers will also survey the remaining concrete dam foundation and develop a plan for removing it during late summer of 2017.

Additionally, USACE engineers will use controlled blasting to remove several large boulders that are limiting fish passage through the former dam sites. Fish have been successfully moving through both dam sites and are recolonizing the upper river, but biologists and river geologists remain concerned about passage impediments created by the boulders and sediment accumulating behind them. Two boulders will be demolished at the Elwha site, with four more at the Glines Canyon site.

Last fall, 14 large boulders were demolished in Glines Canyon, allowing the winter's high flows to move them downstream and open the channel for improved fish passage. Chinook, sockeye, bull trout and summer steelhead have all migrated through both dams to reach the upper river, while adult pink, coho and chum salmon, and Pacific lamprey have passed upstream of the former Elwha Dam site.