8180

• UCREFRP Catalog Number: 8180
• Author: Hamilton, S. J.
• Title: Hypothesis of Historical Effects From Selenium on Endangered Fish in the Colorado River Basin.
• USFW Year: 1999.
• USFW - Doc Type: \
• Copyright Material: YES

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Date

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1987

Recovery Implementation Program for the Endangered Fishes of the Upper Colorado River Basin established (USFWS,

1987).

1991 Minckley el al. (1991) notes native fish abundant before 1900 with reduced occurrence after 1900. "Historical absence of

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1988-89 Selenium elevated in water, sediment, and biota in the Gunnison and Uncomphagre river basins (Butler el aI., 1991).

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1988-90 Selenium elevated in water, sediment, and biota in the Green River basin (Stephens el al., 1992).

1989-95 Only 10 razorback sucker collected in upper Colorado River (McAda, personal communication, 1998).

1990s Razorback sucker in Lake Mohave declining and population crash expected (Marsh, 1993).

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1990s Seven university studies document selenium contamination in lower Colorado River basin.

1990 Bestgen (1990) concludes endangered fish declined before and after dams.

1990-91 Selenium elevated in water, sediment, and biota in the San Juan River basin (Blanchard el aI., 1993; Butler el aI., 1995).

1991 Razorback suckerlisted as endangered (USFWS, 1991).

young fish ... striking."

1991 Selenium elevated in water at several sites on Colorado River (Butler el aI., 1994) where Valdez el al. (1982) collected

endangered fish.

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