Fish Passage in Nevada - Problem Statement

Lahontan cutthroat trout (Oncorhynchus clarkii henshawi)

Man-made barriers to salmonid migration include physical obstacles such as road/stream crossings, irrigation diversions and dams. Road/stream crossings are extremely numerous in Nevada and often cross multiple road ownerships within a watershed. In many instances, passage impediments and delay in migration may negatively affect adult and juvenile fish, preventing the full use of available habitat required to complete salmonid life histories, as well as inflicting injury or death of fish attempting to migrate both up and down stream. In other instances, barriers may benefit native species by limiting competition and hybridization with non-native species. A comprehensive Nevada fish passage program is vital towards identifying, prioritizing, treating (if desired) and managing migration barriers and sources of entrainment so that unimpeded migration of Nevada’s salmonid populations is achieved, with emphasis on native species conservation. Through coordinating resources and authorities and creating the Fish Passage Forum, we will maximize resource efficiency and address Nevada’s comprehensive fish passage needs effectively.

Nevada Fish Passage Working Group

The Nevada Fish Passage Working Group is a consortium of state, federal and non-profit entities that are working to improve aquatic habitat connectivity in Nevada by identifying and managing barriers that prevent or hinder movement and migration patterns of fish and aquatic wildlife species. Migration barriers have the potential to restrict available habitats, interrupt seasonal movement patterns, and lead to individual losses due to isolation events.

A fish management barrier on one of Nevada's small streams

Nevada is the driest state in the nation, and as such water is a very important commodity and it can be assumed that most every perennial water source near agricultural lands has been diverted for beneficial use. At time of construction, most of these historical diversions did not factor in the potential impacts on fish populations. Derby Dam’s impact on the Pyramid Lake cutthroat trout spawning run in the Truckee River, and subsequent demise of the population, is a well-known local example of the impacts that can result from a fish migration barrier. A thriving population of cutthroat trout was eliminated when the diversion dam was construction without accounting for the biological needs of the fish population in Pyramid Lake.

The working group has identified two types of barriers impacting fish and aquatic wildlife populations. Management barriers are structures and devises used to control species movements which were designed and built by scientists. An example of a management barrier would be a gabion barrier placed in a channel to prevent non-native species from immigrating into a habitat and hybridizing or predating upon a native species. Another example may be the placement of a fish-exclusion screen on a water diversion to prevent fish from being washed onto a agricultural field along with irrigation waters.

The second type, migration barriers are natural or manmade structures that are detrimental to fish and aquatic wildlife species by preventing passage or redirecting natural migrations or movement patterns. Commonly migration barriers exist at road crossings (i.e. culverts), dams and natural falls.

Proper management of fish passage barriers and water diversions can be implemented on a variety of water systems and can result in a multitude of benefits for many fish and aquatic wildlife populations throughout Nevada.

Fish Passage Assessment Database (PAD):

A fish migration barrier (and water diversion) on one of Nevada's small streams.

The Nevada Fish Passage Assessment Database contains basic and detailed information on existing and potential barriers to fish migration in Nevada. Using NDOW’s interactive mapping service, users can identify and query existing and potential fish passage barriers and create custom maps depicting barrier locations in relation to a variety of relevant geographic information layers.

Launch Mapping Service

Cooperators

• Bureau of Land Management
• Natural Resource Conservation Service
• Nevada Department of Wildlife
• Trout Unlimited
• U.S. Forest Service
• U.S. Fish and Wildlife Service

The "wall canyon sucker," one of Nevada's native species.

Lahontan cutthroat trout (Oncorhynchus clarkii henshawi)