In addition, given the environmental considerations in large scale irrigation schemes there has been reluctance of financial institutions to engage in these projects irrespective of their overall benefits. The Ogallala has been the source of substantial, large-scale irrigation development, beginning in the 1950s, when affordable technology became available for extracting groundwater and applying it to large fields of cotton, com, winter wheat, and sorghum. The number of wells on the Texas High Plains rose from 48 000 in 1958 to 101 000 in 2000, as farmers increased their production of irrigated crops. The Ogallala is largely a fossil aquifer with a very slow rate of natural recharge.