Washington - President Barack Obama signed legislation on Monday expanding and protecting US public parks and wilderness areas from oil and gas development, billed as the largest US conservation measure in more than 15 years.

    "This legislation guarantees that we will not take our forests, rivers, oceans, national parts, monuments, and wilderness areas for granted," Obama said while signing the Public Land Management Act.

    The legislation - backed by members of both parties - is "among the most important in decades to protect, preserve and pass down our nation's most treasured landscapes to future generations," Obama added.

    The omnibus bill, comprising more than 150 individual measures passed by Congress, creates 10 new National Heritage Areas, designates two million acres (81,000 hectares) of federal lands in nine states as wilderness areas and sets out water conservation measures.

    "It protects treasured places from the Appalachians of Virginia and West Virginia to Michigan's Upper Peninsula, from the canyons of Idaho to the sandstone cliffs of Utah, from the Sierra Nevada in California to the Badlands of Oregon," Obama said.

    "It wisely faces our future challenges with regard to water ... assesses how growth and climate change will affect our access to water resources ... it includes solutions to complex and long-simmering water disputes, he added.

    Obama said water conservation measures would allow the 80,000-strong indigenous Navajo nation "access to clean, running water for the very first time."

    The bill also includes the Christopher and Dana Reeve Paralysis Act - named after the late Hollywood actor who was paralyzed from a riding accident, providing for paralysis research, rehabilitation and care.

    Obama said the bill was "specifically aimed at addressing the challenges faced by Americans living with paralysis" and would work to improve their quality of life "no matter what the costs."

    Reeve's son, Matthew, attended the signing ceremony and was summoned by Obama to also sign the bill.

    Obama signed the bill before 150 people including lawmakers, representatives from conservation groups, sports organizations and disability advocates.

    The United States has currently set aside 107.3 million acres (43.4 million hectares) as wilderness areas, including national parkland.