This Technical Data notebook has been prepared for a Letter of Map Revision application for a portion of the Via Entrada Wash located in Pima County, Arizona. The objective of the TDN and LOMR submission is provide regulatory discharge rates and floodplain limits along the Via Entrada Wash using better topographic, hydrologic, and hydraulic data.

With the passage of the Federal Endangered Species Act in 1973, the stage was set for a confrontation between urban development and the provisions of Federal Law. Language was amended to the Act that established standards that a plan would have to meet before the Fish and Wildlife Service could approve it and issue a permit for the take of a listed species. In those jurisdictions that have adopted this approach, conservation of natural resources is no longer an afterthought but a major element that has to be considered during the regular land use permitting process.