Wise use of water for garden and lawn waterings not only helps protect the environment, but saves money and provides for optimum growing conditions. Simple ways of reducing the amount of water used for irrigation include growing xeriphytic species (plants that are adapted to dry conditions) or native species, mulching, adding water-retaining organic matter to the soil, and installing windbreaks and fences to slow winds and reduce evapotranspiration. The United Nations estimates that over the next twenty years the supply of fresh water per-person will decline by 33%, so every step to conserve water will make a difference.