<P> U.S. President Barack Obama "initially rejected the Keystone XL pipeline in January 2012, saying he wanted more time for an environmental review ." On February 17, 2013, a rally at the National Mall drew an estimated 40,000 in protest of Keystone XL . In January 2014, the U.S. State Department released its Keystone pipeline Final Supplemental Environmental Impact Statement for the Keystone XL Project Executive Summary, which concluded that, according to models, a large crude oil spill from the pipeline that reached the Ogallala could spread as far as 1,214 feet (370 m), with dissolved components spreading as much as 1,050 ft (320 m) further . </P> <P> Since 2010, the North Plains Groundwater Conservation District, which encompasses eight counties north of Amarillo, including Moore and Dallam Counties, has offered a $300,000 annual demonstration project to conserve water that farmers pump from the Ogallala Aquifer . Participating farmers grow corn with just over half of the water that they would normally require to irrigate the fields, or they plant several weeks later than customary . Pivot sprinklers are used in the project, rather than the more expensive drip irrigation . According to district manager Steve Walthour, conservation is essential considering declining levels of the aquifer . The local non-profit organization Ogallala Commons, named for the aquifer itself, which not only collaborates and supports the local communicates, also works to conserve the Ogallala Aquifer and the surrounding area . </P> <P> Eleven farmers in 2013 participated in the conservation program, with some planting in dry earth, rather than watered soil . They are leaving more space between plants, a technique that retains moisture for a longer period of time . Soil sensors permit farmers to gather accurate information about the moisture level of their crops . The motivation to save water comes from the district's regulations on extracting water from the aquifer . The United States Geological Survey determined the water level in the aquifer has dropped more in Texas than in any other state in the basin . </P> <P> Farmers on their own land may draw water without charge from the aquifer . Pumping costs are low because the fuel used, natural gas, is inexpensive . The North Plains district first established limits on pumping in 2005 and tightened the regulations four years later . Certain wells are now required to have meters . Yet another challenge facing the district is that higher prices for crops have prompted some to plant additional fields and further increase the use of water from the aquifer . </P>

Which of these rivers does not cross the great plains region