9380

• UCREFRP Catalog Number: 9380
• Author: U.S. Bureau of Reclamation.
• Title: Grand Valley Irrigation Company Fish Screens ‎(Predesign)‎.
• USFW Year: 2000.
• USFW - Doc Type: Boise.
• Copyright Material: NO

BD = -0.07924 + 0.1583 * TL
RSQ = 0.96, n = 156 (RSQ = standard deviation and n is the number offish sampled)

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Razorback sucker -

BD = -1.181 + 0.2077 * TL
RSQ = 0.97, n = 113

Based upon these relationships for 300 mm fish the BDs are 61.13 mm or 2.4 inches for the

razorback sucker and 47.41 mm or 1.87 inches for the Colorado pikeminnow. Theoretically,

screen openings of 1.87 inches or less could then achieve the desired goal. Some researchers are

concerned that fish could be "gilled," essentially go part way through a 1.87 opening and then

not be able to back out because they would get caught on their gills. Therefore, a maximum

opening of 1 inch was thought to be an appropriate design criteria.

Preliminary estimates conducted as part of this study, indicated that screening to 3/32 inch

opening was only about 17 percent more costly and would be able to prevent most life stages of

the endangered fish from being diverted. At a meeting held in Grand Junction on January 10,

2000, a decision was made to proceed with screen design with 3/32 inch openings. [Note: this

memorandum was prepared prior to this decision and will therefore evaluate all options).

Previous work in the Colorado River at this site included the construction of a fish passage

structure at the GVIC diversion dam. The report, Concept Development Report, Grand Valley

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