One of the greatest changes that has occurred in the Himalaya over the past 50 years is the spread of motor roads, which connect remote towns and villages throughout the mountains, and provide India’s military with access to border regions. In Uttarakhand, many of the highways follow traditional pilgrimage routes to the sources of the Ganga and its tributaries. In 1999, 30 years after my first trek to the Aglar, I decided to undertake the Char Dham Yatra on foot. Motor roads now linked the temples at Yamunotri, Gangotri, Kedarnath, and Badrinath, so that most pilgrims completed this journey by bus. Determined to retrace as much of the old padyatra route as possible, I headed off from Rishikesh on my own. This was the most ambitious series of treks I’ve ever done, breaking the journey into four stages of two to three weeks each, and completing the pilgrimage over the course of a year. Not only was it a physical challenge, but also an opportunity to understand the many connections that exist between geography, ecology, spirituality, myth and folklore. My book, "Sacred Waters: A Pilgrimage to the Many Sources of the Ganga," is a chronicle of that memorable journey.