 Probably one of the oldest methods for irrigating fields is surface irrigation, also known as flood or furrow irrigation. This can be seen beside me. This can be accomplished by digging a ditch at the top of the field. Water running down the ditch eventually hits a canvas dam built by a farmer. This canvas dam can be moved to a desired location in that field. Once the canvas dam is built, small aluminum pipes are used to siphon water out of the ditch to irrigate the crops. Other methods in flood irrigation is made possible through gated aluminum or hard plastic pipe. Each morning or evening, the farmer attending to this water opens and closes the gates to distribute water to different parts of the field. Surface irrigation is used throughout Wyoming today, especially in the farming areas of the North Platte, Big Horn, Laramie, Wind River, and Poposia River watersheds. Nationally, approximately 29.4 million acres of farmland are irrigated by flood irrigation each year, as compared to 28.3 million acres irrigated by spray or sprinkler irrigation. Flood irrigation may not be the most efficient method, but is cheap and low-tech. Whether using gated pipes or crude dirt ditches makes little difference to the crop needing water. All the farmer needs to know is that he or she is using a method that's hundreds of years old in the making. From the University of Wyoming Cooperative Extension Service, I'm Brian Sebade, and this is Exploring the Nature of Wyoming.