The Endangered Species Act (ESA) of 1973  protects plants and animals that are listed by the federal government as "endangered" or "threatened." Populations of animals or plants which are of concern are reviewed  by the US Fish and Wildlife Service and the National Marine Fisheries Service.  After study the agencies make a declaration of the status of the population.  There are three main responses from a study: No action, Threatened and Endangered.  If a species is listed as threatened or endangered the agency must establish critical habitats, and define rules for protecting the species.  The rules for threatened species are much less strict than those listed as endangered.  Once a species is listed, a management plan to recover the population is drawn up and implemented. When the population recovers to the level is it no longer endangered, it is removed from endangered status. If a population which is listed as threatened continues to decline, at a certain level the status is changed to endangered and more strict rules for protecting the population go into effect.

The endangered species act has the ability to significantly impact private and governmental land use, such as modifying or stopping building projects or other activities which may impact the listed species in an area. For example in 1990 the Northern Spotted Owl was listed as endangered  which resulted in millions of acres of Pacific Northwest forests becoming protected habitat. The timber industry was widely affected by the loss of timberlands. Forest workers lost jobs, and homebuilding and real estate interests were impacted. In some places, small  towns which relied on timber employment  became ghost towns as the majority of employment for the town was lost. Businesses closed and people moved away. As the management plans were being created almost all the logging stopped in many areas causing significant uproar and political and social upheaval especially in rural areas.  There were widespread legal challenges, and protests. Logging trucks blocked roads, and there were intense encounters between affected residents, environmental groups and the federal government.   Once the new timber harvest rules were established there was much less logging allowed and many people affected had to change lifestyles.  In many small timber towns there is still a great deal of bitterness about this change.

This kind of wide economic impact has stirred up opposition to the endangered species act, and in some cases, the federal government in general.  The recovery of many species has been slow, although populations of Bald Eagle, and Timber Wolves were recently removed from endangered status because their populations have recovered.

In 2005 populations of Chinook and Coho salmon in the Puget Sound watershed were listed as threatened.  A lawsuit by farmers and the forest and building industry put the issue in court, arguing that wild fish were genetically no different than hatchery fish and that salmon counts should include hatchery fish, thus making the two populations not threatened.  In court rulings the original listing criteria that wild fish populations are different than hatchery fish has been upheld.  Recovery plans for all the river systems which host the threatened populations of salmon have been drafted and are being implemented.

Should the two salmon populations continue to decline, they could be listed as endangered and this has potential  to place restrictions on many activities such as construction, surface water management, forestry and many others,  causing a potential impact on jobs, business, families and the local economy. There are many  people who are afraid that the salmon may become like the Spotted owl causing huge impacts on a variety of people.  While many people are working to save salmon because they want to keep these icons of the  wild alive, the potential of the endangered species act listing is motivating many others to get involved.