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Delta Smelt
The delta smelt, a small planktivorous fish found only in the Sacramento-San Joaquin Delta and upper San Francisco Bay, is considered one of the best indicators of the ecological health of the estuary.
Delta smelt spend most of their one-year life span in the slightly salty waters of Suisun Bay; except in the winter, when they migrate upstream into the Delta to spawn. There, the operations of the giant federal and state water projects, which export huge amounts of water from the Delta, degrade delta smelt habitat and kill large numbers of both young and adult fish.
Pollution from urban and agricultural runoff and the increasing prevalence of harmful invasive species in delta smelt habitat have also impacted the species. Formerly one of the most common fishes found in the ecosystem, the delta smelt population had declined by 90% by the end of the 20th century and is currently at less than 3% of population levels measured just ten years ago. Because of its one year life span and its reliance on Delta habitat, the delta smelt is the Bay-Delta estuary’s most endangered fish.
The Bay Institute has worked to prevent the extinction of delta smelt and the destruction of their habitat, and to promote their long-term recovery, in a number of ways:
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The delta smelt, a small planktivorous fish found only in the Sacramento-San Joaquin Delta and upper San Francisco Bay, is considered one of the best indicators of the ecological health of the estuary. Delta smelt spend most of their one-year life span in the slightly salty waters of Suisun Bay; except in the winter, when they migrate upstream into the Delta to spawn. There, the operations of the giant federal and state water projects, which export huge amounts of water from the Delta, degrade delta smelt habitat and kill large numbers of both young and adult fish.
Pollution from urban and agricultural runoff and the increasing prevalence of harmful invasive species in delta smelt habitat have also impacted the species. Formerly one of the most common fishes found in the ecosystem, the delta smelt population had declined by 90% by the end of the 20th century and is currently at less than 3% of population levels measured just ten years ago. Because of its one year life span and its reliance on Delta habitat, the delta smelt is the Bay-Delta estuary’s most endangered fish.
The Bay Institute has worked to prevent the extinction of delta smelt and the destruction of their habitat, and to promote their long-term recovery, in a number of ways:
- Winning endangered species listing of the species in 1993
- Fighting to force the U.S. Fish and Wildlife Service to adopt more protective regulations
- Working to secure flow and habitat requirements that would support delta smelt recovery in state water quality standards, restoration plans, and other vehicles
In 2007, after The Bay Institute and other groups challenged the inadequate biological opinion governing the impact of water project operations on delta smelt in court, a federal judge found that biological opinion grossly inadequate and ordered the Fish and Wildlife Service to redo it. The Bay Institute’s scientists provided extensive expert testimony and presented detailed recommendations for new protections in the trial. The new opinion, issued in 2008, contained most of the protective actions recommended by the Bay Institute, including strong new limitations on reverse flows in Delta channels from export pumping and new requirements for fall outflows to protect delta smelt habitat.
But a reversal for delta smelt came in 2010 when the same court, in response to a water user lawsuit, threw out parts of the new opinion, claiming scientific uncertainty, even though numerous independent scientific reviews had concluded that these flow requirements and export restrictions were scientifically justified. The Bay Institute and its allies are currently fighting this battle in federal court.
But a reversal for delta smelt came in 2010 when the same court, in response to a water user lawsuit, threw out parts of the new opinion, claiming scientific uncertainty, even though numerous independent scientific reviews had concluded that these flow requirements and export restrictions were scientifically justified. The Bay Institute and its allies are currently fighting this battle in federal court.
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