It’s the summer tourist season, and Yosemite National Park is gridlocked with traffic.

At 12:30 on a Saturday afternoon, a long line of cars, buses and RVs that entered the park at Big Oak Flat move slowly along the main paved road past Cascade Falls and on down to merge with vehicles coming east on Highway 140. A quick left turn brings a car into the line of traffic heading into Yosemite Valley.

Then, all vehicles come to a stop.

For the next two hours, vehicles either sit parked in traffic lanes at a complete halt or they inch forward at a pace far slower than their frustrated passengers, who get out of their vehicles and walk ahead searching for the source of the problem. There are rare surges when vehicles may move forward 100 yards before traffic returns to a gridlocked standstill. There is nowhere to even turn around.

Some drivers and passengers are stoic, others are clearly upset and frustrated by such an inescapable traffic jam.

Near the end of two hours, the traffic finally inches forward to an intersection where two park rangers stand next to a sign. The few vehicles allowed past the rangers apparently face an additional “two-hour delay” according to a message flashing on an electronic sign. But with no parking spaces vacant in the east end of Yosemite Valley, the rangers are simply requiring most drivers (who have already endured two hours of gridlock) to turn north at the Valley crossover and drive back west – out of Yosemite Valley.

Confused drivers appear bewildered and frustrated as they are funneled back out Highway 140 or up Highway 120 – headed back to the park entrances where they came in nearly three hours earlier.

But a new frustration becomes obvious.

Park employees at the entrance stations are still continuing to allow literally hundreds of additional vehicles each hour into the park to jam up behind the already gridlocked traffic. Knowing full well Yosemite Valley is jammed with traffic, park employees are continuing to charge $30 per vehicle and send hundreds of additional vehicles on into the park to literally come to a standstill and then inch forward for hours in a traffic jam. New families become trapped in the traffic jam nightmare.

Sadly, on the major highways leading to Yosemite Park, there are no flashing signs warning approaching visitors that Yosemite Valley is “full with gridlocked traffic.” Families unknowingly continue driving to entrance stations – unaware they might end up circling for hours through a looped traffic jam without ever getting close to seeing Yosemite Falls, the visitor center, or other key destinations.

The precious natural cathedral of Yosemite Valley deserves far better than the park’s current management policy. Jamming the maximum number of visitors into a traffic nightmare not only completely ruins the Yosemite experience, the gridlock concentrates air pollution from idling cars and buses in the narrow valley between towering rock walls.

John Muir and every other champion of Yosemite would be appalled to have Yosemite Valley managed as if it was a packed shopping mall in the midst of holiday sales. Yet, despite so much congestion and crowding, gateway communities continue to avidly market lodging and supplies – no matter how much dissatisfaction results from visitors disillusioned by their actual visit to the overcrowded park.

It was only a few years ago when having 3 million visitors in a year at Yosemite was nearing a record level. Then, as commercial tours and park concessionaire marketing combined to maximize tourism, park visitation climbed to 4 million. Last year, over 5 million visitors crowded into the park, and 2017 is likely to produce a visitor record that spikes even higher. More than 75 percent of those millions of visitors all cram into tiny, vulnerable Yosemite Valley.

Yosemite is a precious legacy, not just for current Americans but for future generations. It is time for the Park Service to set reasonable limits on the number of vehicles allowed into Yosemite Valley on any given day. The current management is defiling and disgracing our national treasure. Those who love Yosemite need to speak up.

John Buckley is executive director of Central Sierra Environmental Resource Center in Twain Harte, California. For years, CSERC has publicly advocated for better management of visitation levels and reasonable limits to be set for the number of vehicles allowed into overcrowded Yosemite Valley.