KUSA - If you're planning a trip to one of America's 400 national parks, this weekend might be a good option as entrance fees are being waived in celebration of National Park Week.

However, if you see some roads in the parks closed or trails blocked, they could be part of projects slated for repairs that have not been funded yet by Congress.

There are about $12 billion worth of repairs at National Parks that have been deferred for years.

Deferred maintenance projects at the Grand Canyon total a huge sum of 371 million dollars.

Rocky Mountain National Park has less than that with about $62 million in deferred projects. Mesa Verde National Park has nearly $57 million. 

Some parks have projects visitors won't see, like sewage systems that need repairs or fresh drinking water systems that need updating.

Officials from "Restore America's Parks" -- a program from the Pew Charitable Trusts – is hoping people will contact Congress to encourage spending on these repairs.

Other parks in Colorado have thousands, sometimes millions of dollars in deferred maintenance. All the projects are from the National Park Service's latest outline from September 2015.

More information on those projects can be found here: http://bit.ly/2ofzhjc