Water supplies in water-rich Prince Edward Island Prince Edward Island is blessed with an abundant supply of water, receiving about 1100 millimetres of precipitation fairly evenly throughout the year. The province depends nearly completely on groundwater supplies for domestic and industrial use. Groundwater is of excellent quality and can be used for drinking without being treated. Prince Edward Island has more than 4000 kilometres of streams, which become mixed with salt water in estuaries for a good part of their length. There are few natural freshwater lakes or ponds, but hundreds of artificial ponds.
Flooding is rare, because the streams are short and the soils and bedrock are permeable.
Precipitation during the growing season is usually adequate, but supplemental irrigation is sometimes needed to obtain optimal yields. Surface water is usually preferred for irrigation because of the lower cost compared with that for groundwater. However, surface waters are often overtaxed because they are limited, and fish habitat must be protected by maintaining a minimum amount of water flow in the stream at all times. The province has developed irrigation policy defining how to allocate available water resources among various users. It encourages extracting groundwater for irrigation, especially where surface water resources are limited or heavily used.