Editing Hoover Dam (section)

== Environmental impact ==
[[File:Water intake towers at Hoover Dam.jpg|thumb|View upstream from Hoover Dam, October 2021, during the [[Southwestern North American megadrought]]]]

The changes in water flow and use caused by Hoover Dam's construction and operation have had a large impact on the [[Colorado River Delta]].{{sfn|Glenn Lee et al.|1996}} The construction of the dam has been implicated in causing the decline of this [[estuarine]] [[ecosystem]].{{sfn|Glenn Lee et al.|1996}} For six years after the construction of the dam, while Lake Mead filled, virtually no water reached the mouth of the river.<ref name="Burns 2001" /> The delta's estuary, which once had a freshwater-saltwater mixing zone stretching {{convert|40|mi}} south of the river's mouth, was turned into an [[inverse estuary]] where the level of [[salinity]] was higher close to the river's mouth.{{sfn|Rodriguez Flessa et al.|2001}}

The Colorado River had experienced natural flooding before the construction of the Hoover Dam. The dam eliminated the natural flooding, threatening many species adapted to the flooding, including both plants and animals.{{sfn|Schmidt Webb et al.|1998}} The construction of the dam devastated the populations of native fish in the river downstream from the dam.{{sfn|Cohn|2001}} Four species of fish native to the Colorado River, the [[Bonytail chub]], [[Colorado pikeminnow]], [[Humpback chub]], and [[Razorback sucker]], are listed as [[endangered species|endangered]].{{sfn|Minckley Marsh et al.|2003}}<ref name="FWS, Colorado River Recovery" />