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Rock Creek, Idaho
As you may know, America has different water rights in the east and west. In the east riparian water rights originate in English common law. If you own land that touches on a water body you have an equal right to use that water. But in the west water rights are known as prior appropriation where ownership of water is separated from land ownership. Water is a commodity, owned for beneficial use. The origin of prior appropriations is based on Spanish law, living in a region where water is precious. Idaho is a semi-arid region with little precipitation and prior appropriation laws. There is water in the Snake River that runs through a deep canyon in the southern valley and is not easily accessible.
The Snake River Plain is a semi-arid fertile region capable of growing potatoes, dry beans, corns, sugar beets, and alfalfa among other crops. But the crops require irrigation to grow well. At the beginning of the twentieth century several small dams were built along the river to provide irrigation water to the plain. Along the middle Snake River Plain numerous canals, such as the High Line Canal, were constructed to bring water to the crops and then return remaining water to the Snake. The High Line is a special type of canal, certainly built for irrigation, but engineered to maintain elevation meandering through the terrain’s contours so it can flow by gravity rather than electric pumping. The technique was perfected by Mormon farmers, who are numerous in southern Idaho. High line canals double or even triple the irrigated land at less expense. But the water at the beginning is markedly different from the end point.
South of Twin Falls the return flow empties into Rock Creek and then the Snake. The problem is that Rock Creek has been considered “one of the most severely degraded streams in the state”[1] due to point and non-point pollution. The crops require many polluting fossil fuel based fertilizers and pesticides. The area has been studied to remove pollutants, and most of the point sources have been eliminated but agricultural pollutants: sediment, phosphorus, nitrogen, and pesticides continue to be a problem. The pollutants are also the result of animal grazing and irrigation. The pollutants impair the drinking water supply, recreation, salmon spawning and fishing. The water entering Rock Creek and returned to the Snake is not the same.
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