National Park Service Is environmentally Responsible

In keeping with its mission to preserve the national environment, the National Park Service deserves praise for transitioning to eco-friendly cleaning methods in recent years. For instance, Mt. Rushmore was cleaned using only sprayed water and without chemical additives in 2005.
​http://www.cleanlink.com/news/article/HFI-Salutes-the-National-Park-Service-During-its-Centennial–20407?email=&utm_source=enewsletterDaily&utm_medium=email&utm_campaign=DailyCP20170124