PUBLIC LANDS -- State and federal land managers are waiving some visitor fees on holidays this year, including the upcoming Martin Luther King holiday.

The extent of the freebies vary among managing agencies.

Washington State Parks offer 12 fee-free days a year while national parks and forests normally offer about half that many.

National Parks, however, are increasing the free-day offerings this year as they celebrate the 100th anniversary of the National Park System.

In Washington, Sno-Park permits are still required even on "fee-free days" in vehicles at state parks, such as Mount Spokane, as well as in national forests, such as at Sherman Pass. The Sno-Park plowing programs are separate from other permit programs such as the state Discover Pass and the federal Northwest Forest Pass.

Here's a rundown of the state and federal fee-free days in 2016.

Washington State Parks and Recreation Commission is offering 12 “free days” during which visitors will not be required to display a Discover Pass to visit a state park.

The normally required Discover Pass costs $30 to be used on two vehicles, or $10 for a one-day permit. The pass is required for any vehicle to access recreation sites managed by Washington State Parks, the Washington Department of Fish and Wildlife and the Department of Natural Resources.

But the free days apply only at state parks; the Discover Pass is still required on WDFW and DNR lands on those "free days."

The remaining 2016 State Parks free days include:

• Jan. 17 and 18 – (Sunday and Monday) Martin Luther King Jr. Day.
• March 19 – (Saturday) Washington State Parks’ 103rd birthday.
• March 26 – (Saturday) A springtime free Saturday.
• April 22 – (Friday) Earth Day.
• May 8 – (Sunday) A springtime free Sunday.
• June 4 – (Saturday) National Trails Day.
• June 11 – (Saturday) National Get Outdoors Day.
• Aug. 25 – (Thursday) National Park Service 100th birthday.
• Sept. 24 – (Saturday) National Public Lands Day.
• Nov. 11 – (Friday) Veterans Day.

The U.S. Forest Service will waive fees at most day-use recreation sites in Oregon and Washington on the following days:

• Jan. 18, Martin Luther King Day.
• Feb. 15, President's Day.
• June 11, National Get Outdoors Day.
• Sept. 24, National Public Lands Day.
• Nov. 11, Veterans Day.

National Park Service fee-free days this year -- 16 in all to celebrate its centennial -- include