>>> back as promised with a controversial idea for one of this nation's great treasures and top destination every time of year and around this time of year, the national parks service wants to make yosemite a road less traveled, reducing congestion and closing some popular concessions and high traffic areas. nbc's harry smith went to yosemite to see how close we're really coming to loving a national park to death.

>> reporter: if you're lucky, you'll get to spend some time in a national park this summer. maybe you'll make it to yosemite . ancient glaciers polish the great granite cliffs of yosemite into a powerful sight, none who see it ever forget it. yosemite is a place so incredible, congress approved the money to preserve and protect it during the thread bear years of the civil war . a half a century later, john mueller , the man who founded the sierra club , brought teddy roosevelt here, and convinced him to expand the park and turn it into a national park . they would be stunned to see that 4 million visitors come here every year, that's double the number from just 30 years ago.

>> too many people here as it is.

>> reporter: so the park service wants to reduce traffic congestion , because it's been designated a wild and scenic river , giving the 81 miles of the merced, which runs through the park, more space. that means doing away with or moving a number of the concessions, bike rental, horseback rides and rafting. they also plan to close two swimming pools. local congressman tom mcclintock thinks it is a bad idea.

>> what they're saying is they're going to move the amenities from the area where people frequent and move them to areas where people don't go. thanks a lot.

>> reporter: yosemite is caught between a rock and a hard place , if you will. here's the problem. the park is the size of the state of rhode island , but most people only use a tiny sliver of it, and that sliver feels an enormous impact. environmentalists like greg adair say the park needs to do much more.

>> somehow we keep getting plans that walk around those issues and don't really face them squarely.

>> reporter: how to preserve a place that means so much to so many people is no easy task. ranger scott getman worked in yosemite for 17 years.

>> we want to make sure that the plan reflects what people want, because when it is all said and done, the national parks belong to the american people .

>> reporter: after all, what's at stake is merely the fate of a priceless national treasure . harry smith , nbc news, yosemite .