Once the partial government shutdown ends -- and it will -- and the National Park System is back in business, advocates want to see Congress properly fund the National Park Service.

Funding long has been an issue for the agency. Groups such as the National Parks Conservation Association and, more recently, the National Trust for Historic Preservation, have pointed out the Park Service's maintenance backlog of some $11.5 billion.

That's just the backlog. NPCA and the Coalition of National Park Service Retirees also have cited less-than-adequate funding for the day-to-day operation of the park system.

According to a recent New York Times article, "The House appropriations bill for the National Park Service would cut $343 million, or 13 percent, from the budget requested by the president, and $240 million from last year’s level."

At the NPCA, Craig Obey, the group's vice president for government affairs, said the persistent underfunding of the parks has to stop.

“One of the things that will not have changed once we’re able to get the parks back open, unless Congress and the president do something about it, is the lack of funding, the underfunding for the parks," Mr. Obey said during a call the other day on the impact of the shutdown. "The underfunding that is impacting the Park Service’s ability to protect these areas and to serve visitors under normal operating circumstances will remain compromised despite the fact that the parks are reopened.”

Alan O'Neill, a former superintendent of Lake Mead National Recreation Area, agreed. He said that about four years ago there was an independent review of the NRA's operational budget and it was found to be highly deficient.

“They determined there was about 50 percent of what was needed to meet minimal acceptable standards. Now, those minimal acceptable standards were defined for every activity, like response to emergency calls, etc., etc.," said Mr. O'Neill, who was on the same conference call. "Now, they’ve lost 100 positions since the time that report was done. So we’re probably around 35 percent of what it takes to meet minimal acceptable standards. Now the community where we operate, the casinos, would never think about operating their casinos at 35 percent of minimal acceptable standards. So this is a serious impact over a number of years.”

Meanwhile, in Virginia, the executive director of the Shenandoah National Park Trust voiced her concern over the funding health of the parks.

"I worry that our national parks won’t be able to fully recover from this hiatus. After a steady decline in federal funding (20 percent over the last decade), intensified by sequestration’s additional 5 percent cuts, our parks are strapped," Susan Sherman wrote in an op-ed piece. "They’re being forced to cut programs and services (Shenandoah National Park eliminated its entire spring season of Park Ranger Programs this year). The National Park Service’s maintenance and repair backlog is in the billions of dollars.

"Each additional day of the government shutdown, our national parks are losing entrance fees—which support visitor-related services. And every day our parks our closed, they lose ground on their tireless work to protect the extraordinary natural and cultural assets housed within."