The author has written an exhaustive documentation of the whole diversity of traditional hydraulic structures in Uttarakhand, including their technology. This monograph is richly illustrated with photographs, maps and several tables. The documentation become very precious as the traditional hydraulics today is a vanishing folk heritage. The book demonstrates the direct relevance of this folk scientific heritage in finding solutions to the prevailing water crisis. The author rules out any solution based on privatization of water. The book strongly pleads for harvesting every drop of rain and every snowflake. The book, written in a very lucid style, is of interest to both a lay reader and a specialist interested in traditional knowledge, culture, hydraulics, and folk heritage.