As a field research biologist, ecologist and science manager, I had the great fortune of working for 40 years in the National Park Service. I was based at Sequoia and Kings Canyon National Park in California’s Sierra Nevada for most of that time.

Our National Park Service is a model for how to conserve natural and cultural resources and, at the same time, provide recreation opportunities for mankind. The parks also preserve our history, from storied battlefields to the homes of many American heroes. The parks tell stories of valor, shame, and hard lessons learned, things that have been valuable for generations past and, hopefully, will inspire generations to come.

But our parks are deteriorating. There is an estimated $11.3 billion backlog in needed maintenance and repairs to our parks across the country.

There are crumbling roads and bridges through the parks; facilities like rest rooms and visitor centers show disrepair. Many memorials and battlefields are overdue for repairs. Problems at some sites pose safety issues to visitors.

Our national parks have suffered as a result of several things. For one, many of the parks’ facilities are aging — some 50-70 years old — and need restoration or replacement. Another cause of wear and tear is the record numbers of visitors to our parks using those facilities.

Congress has not provided the parks with funding necessary to maintain basic infrastructure. As Americans, we all are stewards of the parks, and as such, we should not let this stand.

If we are going to preserve these national treasures properly, we must be committed to making the investments needed. We value the parks for their scenery, plants and animals, and their recreational and educational opportunities, but in addition they are the foundation of local economies in the communities at gateways to the parks.

Congressional funding for the National Park Service’s maintenance budget has, with just a few exceptions, decreased every year for more then a decade.

This makes no sense. The National Park Service is second only to the Department of Defense in the number of assets that it is responsible for maintaining. That includes more than 24,000 buildings, 5,000 miles of paved roads, approximately 18,000 miles of trails and 1,800 wastewater systems.

In California’s national parks alone, there is a backlog in needed maintenance of more than $1.7 billion. At Sequoia and Kings Canyon, the infrastructure needs are more than $145 million. That is third behind Yosemite National Park, with more than $555 million in deferred maintenance, and Golden Gate National Recreation Area, where the number exceeds $298 million.

Congress has a chance to turn the maintenance backlog around. If passed, the bipartisan National Park Legacy Act (S.751/H.R.2584) will ensure that there is dedicated funding for park maintenance in each year’s budget. Highway funding for park roads will increase. The bill also will open up opportunities for partnerships between the public and private sectors to bring about needed park repairs. Deferred maintenance of our parks will be properly addressed.

The national parks that we share with all the plants and animals living there are both our heritage and our legacy. We must stand up for preserving them.

David Graber worked 40 years with the National Park Service and represents the Coalition to Protect America's National Parks.