7845

• UCREFRP Catalog Number: 7845
• Author: Miller, W. J. and D. Laiho.
• Title: Final Report, Upper Colorado River Basin Recovery Implementation Program, Feasibility Evaluation Of Non-Native Fish Control Structures.
• USFW Year: 1997.
• USFW - Doc Type: \
• Copyright Material: NO

Figure 1-2. Example Eicher Screen
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(Source: Clay 1995)
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Characteristics. The Coanda or profile screen is a sloped fixed screen consisting of a wedge-wire
type mesh which allows water to be sheared off and through the mesh as it passes over its
downstream ogee or "profile" face (Figure 1-3). All dewatered debris is collected at the toe of the
screen or occasionally flushed downstream by flows exceeding its design capacity. Its name is taken
from the phenomenon of fluids following a solid surface. It operates under an approach velocity of
in excess of 3 ft/sec.
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Typical Existing Applications. The profile screen's most common application is to achieve direct
diversion of debris free water from a waterway to a hydroelectric facility. It has also been used as
both an upstream (drop type) and downstream (dewatering type) fish barrier, and on irrigation water
diversions. It has been typically utilized on facilities with flows of 0-250 cfs. Most of the 20 plus
project applications are in California.
Typical Advantages
• Self cleaning
• No electrical or mechanical parts
• Available with openings down to 0.5 mm to exclude organic material as small as eggs and larvae
• Operates well under ice conditions
Typical Disadvantages
• The standard design is for less than 1 foot of head on the crest
• Downstream debris collection and processing required
• Requires approximately 5 feet of head below crest (i.e., requires a low dam superstructure)
• Downstream barrier is a short dewatered stream reach
• At small mesh openings, may require specific edge seals (pneumatic) to have edge space as
small as mesh openings
Control Structure Feasibility Evaluation
Miller Ecological Consultants, Inc., February 18, 1997
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