Just a few days after our country’s federally managed public lands conduct one of their biggest celebrations of the year, they could be staring into a financial abyss that will negatively impact their health for years.

Saturday, Sept. 26 is National Public Lands Day, meaning a fee-free day at most federally managed lands, including national parks and U.S. Forest Service sites.

Four days later, the federal fiscal year ends and, without passage of authorization bills or continuing resolutions for stopgap funding, National Park Service units will be closed on Oct. 1, as they during a Congressional stalemate two years ago.

Even more devastating, Sept. 30 also is the expiration for the Land and Water Conservation Fund (LWCF), which has helped maintain and expand protected lands in every state. Since enacted in 1964, the LWCF has been used to protect 2.2 million acres of lands managed by the National Park Service. The LWCF is funded by royalties from offshore oil and gas drilling leases.

(NOTE: Clicking on an image launches a larger-sized viewer).

There is a $4 economic return for every $1 invested by the LWCF, according to the Department of the Interior.

Click here for an interactive map by the Center for Western Priorities showing LWCF impact on national parks

If the LWCF is not renewed, there will be massive long-term consequences for the perpetually strapped NPS, which last year had to defer $11.5 billion in basic maintenance.

A federal shutdown would have shorter-term impacts, but they will be consequential. The NPS suffered a 7.88 million loss in October visitation, due to the 2013 shutdown, leading to a loss of $414 million in visitor spending within gateway communities across the country, according to an agency study. Fourteen national parks were opened with state funding before the end of the shutdown, resulting in $10 of visitor spending for each $1 invested, the NPS also found.

In the meantime, National Public Lands Day is the largest single-day, hands-on volunteer effort to improve and enhance federal, state and local public lands in the country. Last year, about 175,000 volunteers worked at 2,132 sites in every state, the District of Columbia, and Puerto Rico. Visit www.publiclandsday.org for more information and a list of project sites.

Each volunteer who participates in a National Public Lands Day 2015 site at Bureau of Land Management, National Park Service, U.S. Army Corps of Engineers, U.S. Fish and Wildlife Service or USDA Forest Service lands may receive a fee-free coupon good for entry to any participating federal public land, no matter the agency.

Per the NPS, the following national parks, listed by state, are among those that will host volunteer projects on National Public Lands Day:

Alabama: Russell Cave National Monument.
Alaska: Sitka National Historical Park.
Arizona: Canyon De Chelly National Monument, Grand Canyon National Park, Petrified Forest National Park, Saguaro National Park, Tumacacori National Historical Park- Juan Bautista de Anza Trail.
Arkansas: Little Rock Central High School National Historic Site.
California: Channel Islands National Park, Pinnacles National Park, Santa Monica Mountains National Recreation Area, Sequoia and Kings Canyon national Park, Yosemite National Park.
Colorado: Dinosaur National Monument, Florissant Fossil Beds National Monument.
Connecticut: Weir Farm National Historic Site.
Delaware: First State National Historical Park.
Washington, DC: National Capital Parks- East, National Mall and Memorial Parks.
Florida: Everglades and Biscayne National Parks, Gulf Islands National Seashore.
Georgia: Chattanooga National Military Park, Cumberland Island National Seashore, Martin Luther King, Jr. National Historic Site.
Indiana: Indiana Dunes National Lakeshore.
Iowa: Herbert Hoover National Historic Site.
Kansas: Fort Scott National Historic Site.
Louisiana: Jean Lafitte National Historical Park and Preserve/Chalmette Battlefield.
Maryland: Catoctin Mountain Park, Fort Foote Park, Fort Washington Park, Greenbelt Park.
Massachusetts: Boston Harbor Islands National and State Park, Cape Cod National Seashore, Lowell National Historical Park, Minute Man National Historical Park.
Michigan: River Raisin National Battlefield, Sleeping Bear Dunes National Lakeshore.
Minnesota: Mississippi National River and Recreation Area, Pipestone National Monument.
Mississippi: Natchez Trace Parkway/Blackland Prairie National Scenic Trail, Vicksburg National Military Park.
Missouri: George Washington Carver National Monument.
Nebraska: Homestead National Monument of America, Lewis & Clark National Historic Trail.
Nevada: Lake Mead National Recreation Area.
New Hampshire: Saint-Gaudens National Historic Site.
New York: Fire Island National Seashore, Gateway National Recreation Area, Governors Island, Saint Paul’s Church National Historic Site.
North Carolina: Appalachian National Scenic Trail – Fontana Dam, Cape Hatteras National Seashore.
Ohio: Cuyahoga Valley National Park, James A. Garfield National Historic Site, William Howard Taft National Historic Site.
Oregon: Lewis and Clark National Historical Park.
Pennsylvania: Allegheny Portage Railroad National Historic Site, Delaware Water Gap National Recreation Area, Flight 93 National Memorial, Gettysburg National Military Park, Independence National Historical Park, Upper Delaware Scenic and Recreational River.
South Carolina: Congaree National Park.
South Dakota: Mulberry Bend Overlook and Trail, Wind Cave National Park.
Tennessee: Andrew Johnson National Historic Site, Chickamauga and Chattanooga National Military Park, Fort Donelson National Battlefield, Fortress Rosecrans and Old Fort Park, Shiloh National Military Park, Stones River National Battlefield, Fortress Rosecrans.
Texas: Big Bend National Park, Padre Island National Seashore, San Antonio Missions National Historical Park.
Utah: Arches National Park, Cedar Breaks National Monument, Dinosaur National Monument.