Hydraulic Laboratory Report HL-2004-06 

Roza Fish Screens Facility: 

Velocity Measurements at a High 

Canal Flow Rate 

U.S. Department of the Interior 

Bureau of Reclamation 

Technical Service Center

Water Resources Research Laboratory

Denver, Colorado December 2004 
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15-12-2004 Technical Jul - Dec 2004

Roza Fish Screens Facility: Velocity Measurements at a

High Canal Flow Rate

DeMoyer, Connie

U.S. Department of the Interior, Bureau of Reclamation

Water Resources Research Laboratory

P.O. Box 25007, Denver, CO 80225

HL-2004-06

U.S. Department of the Interior, Bureau of Reclamation

Pacific Northwest Region-Yakima Field Office

1917 Marsh Rd., Yakima, WA 98901

USBR

Available from National Technical Information Service, Operations Division, 5285 Port Royal Road, Springfield, Virginia 22161

http://www.ntis.gov

A hydraulic evaluation was conducted in August 2004 at the Roza Fish Screens Facility at a high canal diversion rate of 1911 cfs.

The primary objective of this evaluation was to determine whether primary bypass flow rates can be reduced from the 

recommended operating criteria of 65 cfs to 50 cfs during high canal diversion operations while maintaining drum screen velocity 

criteria. For both operational bypass conditions, approach and sweep velocities were measured near drum screens in two bays at

five vertical locations and seven lateral locations per screen. Velocity data were analyzed for compliance with facility design 

criteria and federal fish protection criteria. Field weir ratings were developed for the full range of primary bypass weir operations.

In the final bypass channel, bypass flow rates were measured for two operational water surface elevations in the secondary 

screening facility.

fish screens, drum screens, screen criteria, velocity measurements, water diversion, fish bypass, sediment sluicing, weir rating

UL UL UL SAR 58

Clifford A. Pugh

303-445-2151
Hydraulic Laboratory Report HL-2004-06 

Roza Fish Screens Facility: 

Velocity Measurements at a High 

Canal Flow Rate 

Connie DeMoyer 

U.S. Department of the Interior 

Bureau of Reclamation 

Technical Service Center

Water Resources Research Laboratory

Denver, Colorado December 2004 
Mission Statements 

The mission of the Department of the Interior is to protect and provide access 

to our Nation's natural and cultural heritage and honor our trust 

responsibilities to Indian Tribes and our commitments to island communities. 

___________________________ 

The mission of the Bureau of Reclamation is to manage, develop, and protect 

water and related resources in an environmentally and economically sound 

manner in the interest of the American public. 

Acknowledgments 

The assistance of Billy Baca of Reclamation’s Water Resources Research Laboratory 

and Allen Kastl of Reclamation’s Yakima Field Office with the field evaluation is greatly 

appreciated. This report was peer reviewed by Tracy Vermeyen of Reclamation’s Water 

Resources Research Laboratory. 

Hydraulic Laboratory Reports 

The Hydraulic Laboratory Report series is produced by the Bureau of Reclamation’s 

Water Resources Research Laboratory (Mail Code D-8560), PO Box 25007, Denver, 

Colorado 80225-0007. At the time of publication, this report was also made available 

online at http://www.usbr.gov/pmts/hydraulics_lab/pubs/HL/HL-2004-06.pdf

Disclaimer 

No warranty is expressed or implied regarding the usefulness or completeness of the

information contained in this report. References to commercial products do not imply 

endorsement by the Bureau of Reclamation and may not be used for advertising or 

promotional purposes. 

This work was conducted by Reclamation’s Water Resources Research 

Laboratory In Denver, CO for Reclamation’s Pacific Northwest Region-Yakima 

Field Office in Yakima, WA.
CONTENTS 

STUDY SUMMARY..........................................................................................1 

Primary Fish Bypass Weirs..............................................................................1 

Final Fish Bypass Weirs................................................................................. 2 

Drums Screens.............................................................................................2 

INTRODUCTION.............................................................................................. 4 

INSTRUMENTATION AND METHODS................................................................ 9 

Primary Fish Bypass Weirs............................................................................ 10 

Final Fish Bypass Weirs.................................................................................12 

Drums Screens........................................................................................... 14 

RESULTS AND DISCUSSION.......................................................................... 18 

Primary Fish Bypass Weirs............................................................................ 18 

Final Fish Bypass Weirs................................................................................ 24 

Drums Screens............................................................................................. 24 

RECOMMENDATIONS..................................................................................... 36 

REFERENCES.............................................................................................. 38 

TABLES 

1 Summary of primary fish bypass data collected in Bays 1, 3, and 5 with a 

 forebay elevation of 1220.4 ft and a water surface elevation of 1213.0 ft 

 in the secondary screening facility............................................................ 20 

2a Average rating table and equation for all primary bypass weirs......................... 22 

2b Bay 1 bypass weir rating table and equation................................................. 22 

2c Bay 3 bypass weir rating table and equation................................................. 23 

2d Bay 5 bypass weir rating table and equation................................................. 23 

3 Final fish bypass velocities and flow rates with an optimal tailwater pool............... 24 

4 Percentage of 7 lateral measurement locations where approach velocity (Va) 

measurements exceed NOAA criteria of 0.4 ft/s and facility design criteria 

 of 0.5 ft/s............................................................................................. 33 

5 Percentage of 7 lateral measurement locations where the sweep-to-approach 

velocity ratio (Vs/Va) does not meet NOAA criteria....................................... 34

FIGURES 

1 Roza Diversion Dam allows water to be diverted through the Roza Fish 

 Screens Facility at the headworks of the Roza Canal.................................... 4 

2 Schematic of Roza Diversion Dam and Roza Fish Screens Facility..................... 5 

3 Bay of rotating drum screens at Roza screening facility with sluice gates 

 installed.................................................................................................9 

4 Adjustable rectangular weir in primary fish bypass channel............................... 10
5 Water flowing freely at a low head over the 2-in-wide, 1.85-ft-long 

 rectangular bypass weir into the downwell................................................. 11 

6 Final fish bypass located downstream of the traveling screens in the 

 secondary screening facility....................................................................... 12 

7 Profile view of secondary screening facility with four vertical traveling 

 screens and a juvenile trapping facility with an adjustable final bypass 

 weir and downwell.................................................................................13 

8 Rotating drum screen with recessed floor in front of the screen and sluice 

 gate installed downstream of the screen..............................................................15 

9 Positioning of ADV at 0.05 times the water depth with the 10-cm sampling 

 location at 3 inches from the drum screen................................................... 16 

10 ADV instrument positioned approximately 3 inches from the screen face 

with the deployment mount...................................................................... 17 

11 The deployment mount was attached to a gantry crane that moved laterally 

 across each drum screen in the bay. ADV data were collected at 

 each location........................................................................................ 17 

12 Primary fish bypass weir rating curve. Measured field data is compared 

 to standard suppressed rectangular weir rating curve for free flow, 

 partially submerged, and submerged conditions.......................................... 21 

13a Sweep (Vs) and approach (Va) velocity distributions on Screen 20 at a 

 Bay 2 fish bypass weir setting of 4.4 ft of head (approximately 65 ft3

/s)............27 

13b Sweep (Vs) and approach (Va) velocity distributions on Screen 20 at a 

 Bay 2 fish bypass flow rate of 50 ft3

/s........................................................27 

14a Sweep (Vs) and approach (Va) velocity distributions on Screen 18 at a 

 Bay 2 primary bypass weir setting of 4.4 ft of head (approximately 65 ft3

/s)...... 28 

14b Sweep (Vs) and approach (Va) velocity distributions on Screen 18 at a 

 Bay 2 primary bypass flow rate of 50 ft3

/s.................................................. 28 

15a Sweep (Vs) and approach (Va) velocity distributions on Screen 17 at a 

 Bay 2 primary bypass weir setting of 4.4 ft of head (approximately 65 ft3

/s)...... 29 

15b Sweep (Vs) and approach (Va) velocity distributions on Screen 17 at a 

 Bay 2 primary bypass flow rate of 50 ft3

/s............................................................ 29 

16a Sweep (Vs) and approach (Va) velocity distributions on Screen 5 at a 

 Bay 5 primary bypass weir setting of 4.4 ft of head (approximately 65 ft3

/s)........30 

16b Sweep (Vs) and approach (Va) velocity distributions on Screen 5 at a 

 Bay 5 primary bypass flow rate of 50 ft3

/s............................................................... 30 

17a Sweep (Vs) and approach (Va) velocity distributions on Screen 3 at a 

 Bay 5 primary bypass weir setting of 4.4 ft of head (approximately 65 ft3

/s)........31 

17b Sweep (Vs) and approach (Va) velocity distributions on Screen 3 at a 

 Bay 5 primary bypass flow rate of 50 ft3

/s....................................................31 

18a Sweep (Vs) and approach (Va) velocity distributions on Screen 2 at a 

 Bay 5 primary bypass weir setting of 4.4 ft of head (approximately 65 ft3

/s)........32 

18b Sweep (Vs) and approach (Va) velocity distributions on Screen 2 at a 

 Bay 5 primary bypass flow rate of 50 ft3

/s.................................................. 32 

19 Ratio of sweep-to-approach velocity in front of Bay 2 screens.......................... 35 

20 Ratio of sweep-to-approach velocity in front of Bay 5 screens.......................... 35 

APPENDIX I: Velocity Measurements at Drum Screens 

APPENDIX II: Velocity Distributions in Front of Drum Screens 
STUDY SUMMARY 

A hydraulic evaluation was conducted in August 2004 at the Roza Fish Screens Facility 

at a high canal diversion rate of 1911 ft3

/s. The primary objective of the evaluation was 

to determine whether primary bypass flow rates can be reduced to 50 ft3/s during high

canal diversion operations while minimizing stress on downstream-migrating salmon and 

maintaining drum screen velocity criteria. In order to accurately set bypass flow rates in 

the screening bays, weir ratings were developed for the full range of weir operations. In 

the final bypass channel, appropriate weir heights were set for two operational water 

surface elevations in the secondary screening facility. The corresponding bypass flow

rates were measured in the final bypass channel. 

Approach and sweep velocities were measured in Bays 2 and 5 near six rotating drum

screens under two operational conditions: 

• Recommended operating primary bypass flow rate – bypass weirs set to 4.4 ft of 

head on the weir crest to pass approximately 65 ft3

/s. 

• Reduced primary bypass flow rate – bypass weirs set at 3.35 ft of head on the 

weir crest to pass approximately 50 ft3

/s. 

Velocities were measured near each drum screen at five vertical locations (0.05, 0.2,

0.5, 0.8, and 0.9 times the water depth) and seven lateral locations across the screen at 

a distance of approximately 3 inches in front of the drum screen face. For both bypass 

flow rate conditions, velocity data were analyzed for compliance with facility design 

criteria and National Oceanic and Atmospheric Administration (NOAA) fish protection

criteria. 

Conclusions from this evaluation include: 

Primary Fish Bypass Weirs 

• Primary bypass weirs are generally operated as submerged weirs. 

• The onset of submergence occurs at approximately 2.8 ft of head on the weir 

(39.6 ft3

/s) with a water surface elevation of 1213.0 ft in the secondary screening 

facility. 

• The bypass weirs cannot be considered suppressed rectangular weirs since the 

weir crest is partially contracted by 0.15 ft and the vertical sidewalls of the 

downwell are wider than the sidewalls of the approach channel, allowing for 

lateral contraction or expansion of the overflow jet. The standard weir rating for 

a partially contracted weir cannot be applied for several reasons: the adjustable 

weir blades are not sharp-crested, an aerated nappe is not maintained during 

operation in a partially submerged condition, and the weirs are typically operated 

in a submerged condition. 

• An average leakage rate of 1.5 cfs exists at the adjustable weir gates. 

• Field weir ratings for Bays 1, 3, and 5 are consistent when free flow and partially 

submerged conditions exist. Under submerged conditions, upstream bays (Bay 

1) with longer fish bypass pipes become less efficient due to pipe headlosses. 

1
• Although weir ratings vary slightly between bays, the general primary bypass 

weir rating equation can be used to calculate primary bypass flow rates or set 

bypass weirs with a water surface elevation of 1213.0 ft in the secondary 

screening facility:

Q = 1.5537 – 1.3761 H + 8.4316 H2

 – 1.1012 H3 

where H is the head on the weir in feet and Q is the bypass flow rate in ft3/s. 

• From the weir ratings, the primary bypass flow rate for the recommended weir 

setting of 4.4 ft of head is 64.9 ft3

/s. To achieve a reduced bypass flow rate of 50 

ft3

/s, the primary bypass weirs should be set to 3.35 ft of head. 

Final Fish Bypass Weirs 

• At a secondary screening elevation of 1213.0 ft with no juvenile fish ramp

installed, 3.0 ft of head on the final bypass weir is needed to maintain an optimal 

tailwater pool for safe fish passage. This corresponds to a final bypass flow rate 

of 40.4 ft3

/s.

• At a secondary screening elevation of 1213.8 ft with the juvenile fish ramp

installed, 3.6 ft of head on the final bypass weir is needed to maintain an optimal 

tailwater pool for safe fish passage. This corresponds to a final bypass flow rate 

of 39.9 ft3

/s.

• Measured final bypass flow rates are 25 percent higher than measurements in 

previous evaluations, possibly due to differences in the downwell condition set by 

the weir operator or bypass pipe blockage in previous evaluations. 

Drums Screens 

• A more detailed velocity distribution across the drum screen faces provides a 

better understanding of flow conditions near the screens. 

o Approach velocities measured at 0.05 and 0.5 times the water depth are 

represented by measurements at 0.2 times the depth. 

o Approach velocities measured at 0.8 times the water depth are typically 

higher than velocities measured at shallower depths. 

o Approach velocities measured at 0.9 times the water depth are significantly 

higher than velocities measured at shallower depths. The sluice gate 

placement and/or recessed floor may contribute to high velocities near the

drum screens at the bottom of the water column. 

• At the operating criteria of 4.4 ft of head on the primary bypass weirs, approach 

velocities measured at depths below the curvature of the screen exceed criteria 

more frequently than shallower measurements. 

o Approach velocities exceed the 0.4 ft/s NOAA screen criteria at 75 percent

of 189 total measurement locations and 100 percent of locations at the 

deepest measurement depth. 

o Approach velocities exceed the 0.5 ft/s facility design criteria at 58 percent

of 189 total measurement locations and 100 percent of locations at the 

deepest measurement depth. 

• At the operating criteria of 4.4 ft of head on the primary bypass weirs: 

o For all data collected in Bays 2 and 5, 49 percent of 189 total measurement 

locations and 100 percent of locations at the deepest measurement depth 

have sweep-to-approach velocity ratios less than 2:1. 

o For data collected in Bay 5, 73 percent of 84 total measurement locations 

and 100 percent of locations at the deepest measurement depth have 

sweep-to-approach velocity ratios less than 2:1.

2
o For data collected in Bay 2, 30 percent of 105 total measurement locations 

and 100 percent of locations at the deepest measurement depth have 

sweep-to-approach velocity ratios less than 2:1.

• When the primary bypass flow rate was reduced from 65 ft3

/s to 50 ft3/s, sweep 

velocities decrease and, at some screens, approach velocities increase. Sweepto-approach velocity ratios are less than 2:1 at 82 percent of 168 total 

measurement locations in Bays 2 and 5 and approach velocities exceed 0.4 ft/s 

at 92 percent of 168 measurement locations. 

• At both bypass flow rates, sweep velocities do not produce a clear acceleration 

along the screens into the fish bypass channel. 

• At both bypass flow rates, velocity distributions across the screens are 

nonuniform with the highest velocities occurring at the most upstream screen in 

each bay. 

• Drum screen submergence was 76 percent of the water depth at the screen seat 

for all tests.

3
INTRODUCTION

Roza Diversion Dam is part of the Roza Division of the Bureau of Reclamation’s Yakima 

Project. The dam is located 12 miles north of the city of Yakima on the Yakima River at 

River Mile 127.9. The dam diverts up to 2,200 ft3/s of water from the Yakima River into

the Roza Canal to provide water for irrigation and power generation. The canal 

headworks consist of a concrete structure in the right abutment with a trashrack at the 

inlet to protect a series of rotating fish screens (Figure 1). The Roza Fish Screens 

Facility protects fish from being entrained in the Roza Canal. 

The facility consists of 27 drum screens (17 ft diameter, 12 ft width) in 5 bays with 7 

screens in the upstream bay and 5 screens in each of the following bays. Bays are 

numbered from upstream to downstream and screens are numbered from right to left 

looking downstream with Screen 1 on the right side of the most downstream Bay 5

(Figure 2). Each bay contains a primary fish bypass (referred to as an intermediate fish 

bypass in some previous reports). An adjustable rectangular weir gate in each primary 

bypass controls flow through the fish bypass system. The closed conduit primary 

bypasses converge into a secondary screening facility where excess water is recovered 

through four vertical traveling screens. The final fish bypass returns fish to the Yakima 

River at an outfall downstream of Roza Diversion Dam. 

Figure 1. – Roza Diversion Dam allows water to be diverted through the Roza 

Fish Screens Facility at the headworks of the Roza Canal.

4
Drum Screen #5 

Drum Screen #21 

Drum Screen #27 

Figure 2. – Schematic of Roza Diversion Dam and Roza Fish Screens Facility. 
A forebay elevation of 1220.5 ft is maintained through automatic control of the roller 

gates at the Roza Diversion Dam. At the fish screening facility, the forebay water 

surface elevation is measured at the staff gage in Bay 1. Since the staff gage datum is 

0.1 ft lower at the screening facility, the forebay elevation reads 1220.4 ft at the standard 

operating water level. Operating Criteria for the Roza fish bypass system was 

recommended in 1989 by the National Marine Fisheries Service (Pearce, 1989). The 

National Marine Fisheries Service (NMFS), the previous name designation for the 

fisheries division of the National Oceanic and Atmospheric Administration (NOAA), is 

currently referred to as NOAA. This document specifies that the five primary bypass 

weir gates should be set to an elevation 4.4 ft below the upstream water surface to 

promote fish passage. The surplus weir gates in the secondary screening facility should 

be equally set such that the water surface elevation in front of the traveling screens is 

1213.0 ft. When the juvenile trap is installed in the final fish bypass during juvenile

migration season, the secondary water surface elevation should be set to 1213.8 ft to 

provide adequate flow into the trap. 

The fisheries division of NOAA has developed fish screen criteria and guidelines to 

promote safe passage of fish through screening facilities (NOAA draft, 2004). Criteria 

relevant to this particular study include: 

• Approach velocity normal to the screen face must be less than 0.4 ft/s. 

• Sweeping velocity parallel to the screen face must be greater than approach 

velocity. Optimally, sweeping velocity should be 0.8 ft/s to 3.0 ft/s (minimum 

sweep-to-approach velocity ratio of 2:1). 

• A uniform velocity distribution should be maintained over the screen surface 

to minimize approach velocities. Approach and sweep velocities should be 

measured approximately 3 inches from the screen face for every 5 percent of 

the screen area. Uniform approach conditions are achieved when no 

individual approach velocity measurement exceeds 110 percent of the 0.4 ft/s 

criteria, or 0.44 ft/s. 

• At no point shall flow decelerate along the screen face or in the bypass 

channel. The minimum bypass entrance flow velocity should be greater than 

110 percent of the maximum velocity upstream of the bypass entrance. 

• For rotating drum screens, the design submergence must be between 65 and 

85 percent of the drum diameter. 

The NOAA fish passage criteria also states in Section 12.3 that if a fish screen was 

constructed to NOAA criteria established August 21, 1989 (prior to the establishment of 

these criteria), approval of these screens will be considered, providing that all of the 

following conditions are met: 

1) The entire screen facility is still functioning as designed. 

2) The entire screen facility has been maintained and is in good condition. 

3) When the screen media wears out, it shall be replaced with screen media 

meeting the current criteria stated in this document. 

4) No mortality, injury, entrainment, impingement, migrational delay or harm 

to anadromous fish has been noted that is being caused by the facility. 

5) No emergent fry are likely to be located in the vicinity of the screen, as 

agreed to by a NOAA resource biologist familiar with the site. 

6
Original fish passage facility design information from the Bureau of Reclamation Pacific 

Northwest Region Fish Screen Design Criteria Manual specifies that the maximum 

design approach velocity is 0.5 ft/s and that sweep velocities should be between 1.6 ft/s 

and 1.9 ft/s. Field velocity measurements near the drum screens and in the fish 

bypasses should be obtained periodically or when operational or structural changes 

occur at the screening facility to assure that original design criteria and/or NOAA fish 

passage criteria are satisfied. 

Pacific Northwest National Laboratory (PNNL) has conducted many fish screen 

evaluations in the Yakima River Basin since 1985. Methods to evaluate screening 

facilities were developed and applied during the PNNL studies (Abernathy et al., 1989, 

1990; Blanton et al., 1998, 1999; Carter et al., 2002; Chamness et al., 2001). In July 

2003, Battelle-Pacific Northwest Division measured water velocities in front of drum 

screens in two of the five screening bays, in their associated primary fish bypasses, and 

in the secondary screening facility and final bypass at a canal flow rate of approximately 

1,850 ft3

/s. This evaluation was conducted under two operational conditions (McMichael 

et al., 2003): 

1.) Fish bypasses set to the recommended operating criteria of 4.4 ft of head on the 

weir (corresponding to approximately 65 ft3

/s per bypass) at a forebay elevation 

of 1220.4 ft and a secondary screening water surface elevation of 1213.0 ft. 

2.) Fish bypasses set to half of the recommended operating criteria (corresponding 

to approximately 32 ft3

/s per bypass) at a forebay elevation of 1220.4 ft and a 

secondary screening water surface elevation of 1213.8 ft. 

Results show that NOAA screen criteria were not met at several screens when the fish 

bypass flows were operated both in and out of operating criteria. Before the evaluation, 

sluice gates (porosity boards) were installed behind the drum screens in nonuniform 

configurations. The sluice gates were suspected to be a potential cause for the adverse 

and inconsistent hydraulic conditions at the screen faces. 

In March 2004, velocities were measured near to the drum screens at 0.2 and 0.8 times 

the water depth and three lateral locations per screen. Velocities were collected in front 

of all drum screens in all bays to determine the effect of the sluice gates on the hydraulic 

performance of the drum screens at a canal flow rate of 820 ft3

/s (DeMoyer & Vermeyen, 

2004). Sluice gates were installed in a uniform configuration prior to the evaluation. 

Tests were conducted with sluice gates installed and removed at the operating bypass 

criteria of 4.4 ft of head on the primary bypass weirs and a secondary screening water 

surface elevation of 1213.8 ft. Results indicated that sluice gates did not have a 

negative impact on hydraulic conditions at the drum screens. However, the estimated 

flow rate through the drum screens was lower than the reported canal discharge, which 

suggested that high velocity regions on the drum screens may have been missed. 

Results also showed that downstream primary bypass channels pass more water than 

upstream bypasses at the same weir setting. 

The primary objective of the August 2004 hydraulic evaluation was to determine whether 

primary bypass flow rates can be reduced during high canal diversion operations to 

minimize stress on downstream-migrating salmon while maintaining drum screen 

criteria. The following data was collected in support of this effort: 

 

7
1.) Field ratings of primary and final bypass weirs.

Before this evaluation, bypass flow rates were estimated using a standard weir 

rating for a suppressed rectangular weir (Bureau of Reclamation, 2001). More 

accurate bypass ratings were developed for Bays 1, 3, and 5 to better quantify 

bypass flow rates. 

2.) Detailed velocity measurements in front of screens in Bays 2 and 5. 

During the July 2003 and March 2004 evaluations, velocity data were collected at 

standard measurement locations of 0.2 and 0.8 times the water depth at three 

lateral locations per screen. Results indicated that six measurements per screen 

may not be sufficient to thoroughly define the flow field near to the drum screens. 

For this evaluation, velocities were measured at 5 depths and 7 lateral locations 

in an effort to more accurately define velocity distributions. This detailed 

collection scheme was used to determine if primary bypass flow rates can be 

reduced without negatively impacting the hydraulic performance of the drum 

screens. Data were collected with: 

 Primary fish bypasses set to the operating criteria of 4.4 ft of head on the 

weir (approximately 65 ft3

/s). 

 Primary fish bypasses set to a reduced bypass flow rate of 50 ft3

/s. 

Using the field ratings, the primary bypass weirs were accurately set and the effect of 

reducing the primary bypass flow rate on compliance with NOAA fish screen criteria was 

documented. 

8
INSTRUMENTATION AND METHODS 

A hydraulic evaluation was conducted from July 27 – August 4, 2004 at the Roza Fish 

Screens Facility during a canal diversion of 1911 ± 4 ft3

/s. The forebay elevation was 

1220.38 ± 0.02 ft with corresponding forebay water depths of 11.99 ± 0.02 ft. Drum 

screen submergence was 76 percent of the water depth at the screen seat. Sediment 

sluice gates (porosity boards) were installed downstream of each rotating drum screen in 

the stoplog slots. The sluice gates were placed 1 ft above the channel bottom to 

increase velocities near the bed as a means of reducing fine sediment deposits in front 

of the screens. The top of the sluice gates was about 1 ft below the water surface, 

allowing overtopping flow. The sluice gates were installed throughout this study. 

Figure 3. – Bay of rotating drum screens at Roza screening facility with sluice gates installed. 

The water surface in the secondary screening facility was maintained at the design 

elevation of 1213.0 ft which corresponds to a 12.0 ft water depth. At the onset of testing, 

primary bypass weirs were set to the operating criteria of 4.4 ft of head on the weir. 

A downlooking 10-MHz SonTek Acoustic Doppler Velocimeter (ADV) was used to collect 

three-dimensional velocity data at a location 10 cm below the receiver at a sampling rate 

of 25 Hz for 60 seconds. The data were then time-averaged to obtain mean velocities at 

each measurement location with an accuracy of approximately 1 percent of the 

measured velocity range of 3 ft/s. 

Velocity data were measured with the ADV in the following locations: 

1.) Velocity data were measured at the bypass centerline at 0.2 and 0.8 times 

the water depth in primary bypass channels 1, 3, and 5 and in the final 

bypass. Data collected in May 2004 showed that centerline velocities

adequately represented velocities across the width of the bypass channel 

(DeMoyer and Vermeyen, 2004). 

9
2.) Approach and sweep velocities were measured approximately 3 inches (or as 

close as possible) in front of Screens 17, 18, 20 in Bay 2 and Screens 2, 3, 5 

in Bay 5. Data were collected at 0.05, 0.2, 0.5, 0.8, and 0.9 times the water 

depth and laterally at 0.5, 2, 4, 6, 8, 10, and 11.5 ft from the upstream edge of 

each screen. 

Primary Fish Bypass Weirs 

To develop weir rating tables and equations, ADV velocities were measured over a 

range of head values in the primary bypasses of Bays 1, 3, and 5. Water sweeping past 

the drum screens rounds 90-degree bend from the screening bay into a 2-ft wide fish 

bypass channel. A ramped floor increases the fish attraction flow over an adjustable

partially contracted rectangular weir (Figure 4). The weir frame obstructs 0.075 ft of flow 

on both sides of the channel so that the effective length of the weir blade is 1.85 ft. 

Leakage occurs along the bottom and sides of the adjustable weir frame. The steel weir 

blade is a 2-in-wide, curved blade. Water passing over the weir enters a downwell with 

a 30-inch steel bypass pipe to convey bypassed water and fish to the secondary 

screening facility (Figure 5). 

Figure 4. – Adjustable rectangular weir in primary fish bypass channel. 

10
Weir blade

Figure 5. – Water flowing freely at a low head over the 2-in-wide, 1.85-ft-long rectangular

bypass weir into the downwell. 

Reclamation’s Water Measurement Manual (Bureau of Reclamation, 2001) defines the 

measurement of head on a weir as the difference between the weir crest elevation and 

the water surface elevation upstream of the weir at a distance of at least four times the 

maximum head on the weir crest. Since the approach channel upstream of the weir is 

shorter than the required distance for the upstream water surface elevation 

measurement and water depths do not vary significantly between bays, the forebay 

elevation was measured at the staff gage in Bay 1. 

Free flow occurs when the weir blade is at a higher elevation than the tailwater elevation 

and the overflow nappe is fully aerated. The upstream water surface elevation controls 

the amount of flow that passes over the bypass weirs at a given weir setting. For 

rectangular weirs operating in a free flow condition, the standard power law equation is 

of the form: 

Q = C L H 3/2

where Q = discharge over weir (ft3

/s), L = length of weir crest (ft), H = head 

above the weir crest (ft), C = coefficient of discharge (ft1/2/s).

The weir is partially submerged when the weir blade elevation is higher than the tailwater 

elevation and the nappe is not fully aerated, causing the nappe to attach to the 

downstream weir blade. Under partially submerged conditions, the downstream water 

surface elevation may affect weir performance and the standard weir equation may not

produce accurate values. A fully submerged condition exists when the tailwater 

elevation is higher than the weir blade elevation. When weirs are submerged, both the 

upstream and downstream water surface elevations control weir performance and the 

standard weir equation cannot be applied. 

The steel mount supporting the ADV was inserted into stoplog slots just upstream of the 

onset of the ramped floor. For each bypass, velocity data were measured at the bypass 

11
channel centerline at 0.2 and 0.8 of the water depth to obtain a mean bypass channel 

velocity over the cross sectional flow area. Velocity data were collected from 0.0 ft head 

(including only gate leakage) to 5.0 ft head (maximum achievable head between the weir 

crest and the Bay 1 staff gage water surface elevation) at incremental head increases of 

0.5 ft. The upstream water surface elevation and weir blade elevation were used to 

calculate the head on the weir. Due to heavy turbulence in the downwell, the tailwater 

surface elevation could not be precisely measured. The approximate tailwater elevation 

for each weir setting was used to determine whether the weir was operating in a free 

flow, partially submerged, or submerged condition.

Final Fish Bypass Weirs 

The 2-ft-wide final bypass channel is located downstream of the secondary screening 

facility (Figure 6). A metal ramp transitions flow from the 1201.0 ft floor elevation of the 

secondary screening facility to the final bypass floor elevation of 1207.5 ft. An 

adjustable rectangular weir with a 2-inch-wide curved weir blade (similar to the primary 

bypass weirs) controls the flow rate into the final fish bypass conduit that returns fish to

the river (Figure 7). 

Final fish bypass 

entrance 

Figure 6. – Final fish bypass located downstream of the traveling screens in the secondary 

screening facility. 

12
Figure 7. – Profile view of secondary screening facility with four vertical traveling screens and a juvenile trapping facility wit

final bypass weir and downwell.
The water surface elevation in the secondary screening facility and the operational weir 

setting controls the head on the final bypass weir. Under standard operations, the 

design-specified water surface elevation in front of the traveling screens is 1213.0 ft. 

During the juvenile migration season, a temporary grated metal ramp is installed in the 

final bypass to guide fish into a juvenile trap. When the juvenile trap is installed, the 

water surface elevation must be set to 1213.8 ft to provide adequate flow into the trap. 

The final bypass weir is only operated such that fish have an adequate tailwater pool for 

safe passage into the final bypass pipe. An unacceptable downwell condition means 

that an insufficient tailwater pool is available for juvenile fish and water passes directly 

into the final bypass pipe or too much water floods the juvenile trapping facility, making it 

inaccessible and ineffective. With these operational restraints, a full rating of the final 

bypass weir could not be performed. For each operational water surface elevation 

(1213.0 ft or 1213.8 ft), the weir could be set to only one head value to maintain an 

optimal tailwater pool for fish passage. 

Velocity measurements were taken near the entrance of the final bypass channel 

immediately upstream from the temporary juvenile trap ramp. Like the primary 

bypasses, velocity measurements were collected at the bypass centerline at 0.2 and 0.8 

times the water depth. The water depth was measured with a staff gage at the 

measurement location. Data were collected at 1213.0 ft with the juvenile ramp removed 

and at 1213.8 ft with the juvenile ramp installed.

Drum Screens 

Approach and sweep velocities are the typical velocity components analyzed during fish 

screen evaluations. According to NOAA, the approach velocity in a fish screen 

evaluation is defined as the water velocity component perpendicular to and 

approximately three inches in front of the screen face. The sweeping velocity is defined 

as the water velocity component parallel and adjacent to the screen face. 

Three-dimensional velocity data were measured with the ADV in front of Screens 17, 18, 

20 in Bay 2 and Screens 2, 3, 5 in Bay 5. Data was collected at 0.2, 0.5, 0.8, and 0.9

times the water depth and laterally at 0.5, 2, 4, 6, 8, 10, and 11.5 ft from the upstream 

edge of each 12-ft-wide screen. Data were also collected at 0.05 times the water depth 

during the first test in Bay 2 at the operating fish bypass criteria. Since the velocity data 

collected at 0.05 depth were similar to velocity data at 0.2 depth, data was not collected 

at 0.05 for any other conditions. During the same first test, data was collected laterally 

at 0 ft and 12 ft from the edges of the screens. Since rubber seals along the outside

edges of the screens blocked flow through the screen, data was collected laterally at 0.5 

ft and 11.5 ft for the remaining tests. 

To determine the mean velocity in a channel greater than 2 ft deep with a fully 

developed velocity profile, velocity data is typically measured at 0.2 and 0.8 times the 

water depth. In a previous PNNL study at the Roza facility by Abernathy et al. (1989), 

velocities measurements were made near to the drum screens at depths of 0.05, 0.2, 

0.5, 0.8a, and 0.9. Since velocity data is difficult to collect underneath the curvature of 

the drum screen, additional measurements were made by PNNL at 0.8 times the depth 

on a vertical plane in front of the drum screen (point 0.8). Results from the 1989 study 

indicated that velocities measured at 0.05 and 0.5 were accurately represented by the 

14
standard measurements at 0.2 and 0.8 of the water depth. Limited velocity data 

collected near to the screen face at 0.8a and 0.9 indicated that sweep and approach 

velocities may be higher at these locations. 

Since measurements at 0.2 and 0.8 often accurately represent the vertical velocities 

experienced over the height of the drum screen, this method has become the standard 

for evaluating velocities near fish screens in the Yakima River Basin. In this evaluation, 

a more detailed velocity distribution, like the 1989 study, was performed in order to fully 

evaluate the impact of reducing the primary bypass flow rate, particularly in areas 

affected by the sluice gates and central dividing piers between screens. 

Upstream of the drum screen seat, the forebay floor drops by 1 ft (Figure 8). Fractional 

water depths are based on the forebay floor elevation as measured from the water 

surface. With 76 percent screen submergence, the 0.05, 0.2, and 0.5 depth 

measurements are at or above the centerline of the drum and the ADV can be easily

positioned close to the screen face (Figure 9). Since the 0.8 and 0.9 depths are well 

below the curvature of the drum screens, access to the screen face is difficult for large 

diameter drum screens such as the Roza screens (Figure 8). 

Figure 8. – Rotating drum screen with recessed floor in front of the screen and sluice gate 

installed downstream of the screen. 

15
Figure 9. – Positioning of ADV at 0.05 times the water depth with the 10-cm sampling 

location at 3 inches from the drum screen. 

Maintaining an upright probe orientation, it was not possible to obtain near-screen 

measurements of 3 inches from the rotating fish drum at the 0.8 and 0.9 depths in this 

study. Due to limitations in the ADV mount and the body shape of the ADV instrument, 

velocity measurements could only be taken approximately 19 inches at 0.8 depth and 28

inches away at 0.9 depth from the screen face. Inverting the probe was considered but

not performed due to the high probability of equipment damage from unprotected probe 

transducers contacting the screen face, the probe cable hanging up on bottom debris, 

and silt deposition restricting lateral movement. 

The ADV deployment mount was reused from the July 2003 evaluation (McMichael et 

al., 2003). The 23-ft-long L-shaped steel frame allowed adjustments for the depth of the 

ADV in the water column and the distance from the screen face (Figure 10). Once the 

ADV was positioned at the proper depth, the assembly was fixed to a gantry crane and 

positioned laterally along the screens (Figure 11). In each bay, all lateral locations were 

measured at one depth before the mount was detached from the gantry crane and 

removed from the water. The probe was repositioned on the mount and the instrument 

was redeployed to measure all lateral locations at another depth. 

16
ADV instrument 

Figure 10. – ADV instrument positioned approximately 3 inches from the screen face 

with the deployment mount. 

ADV deployment 

mount 

Figure 11. – The deployment mount was attached to a gantry crane that moved laterally 

across each drum screen in the bay. ADV data were collected at each location. 

17
RESULTS AND DISCUSSION 

Primary Fish Bypass Weirs 

Results of the primary fish bypass evaluation for Bays 1, 3, and 5 are given in Table 1. 

Field rating data were collected with a water surface elevation of 1213.0 ft in the 

secondary screening facility and an upstream water surface elevation of 1220.4 ft at the 

staff gage in Bay 1. The water depth at the staff gage in Bay 1 was approximately 11.99 

ft. Measured leakage rates were 1.2, 1.4, and 1.9 ft3

/s for bypass weirs 1, 3, and 5, 

respectively. The average leakage rate was approximately 1.5 ft3

/s with zero head 

above the weir crest. 

The bypass weirs cannot be considered suppressed rectangular weirs since the weir

crest is partially contracted by 0.15 ft and the vertical sidewalls of the downwell are wider 

than the sidewalls of the approach channel, allowing for lateral contraction or expansion 

of the overflow jet. The standard weir rating for a partially contracted weir cannot be

applied for several reasons: the adjustable weir blades are not sharp-crested, an aerated 

nappe is not maintained during operation in a partially submerged condition, and the 

weirs are typically operated in a submerged condition. Since the standard suppressed 

weir equation was used to estimate bypass flow rates before field weir ratings were 

developed, a comparison of the standard suppressed weir equation and the measured 

field rating data is presented in Figure 12. 

The condition of the nappe was difficult to observe due to the site layout. For head 

values less than 1.5 ft, the nappe appeared to spring free of the weir blade such that free 

flow conditions existed. For head values between 1.5 ft and 2.8 ft, the nappe did not 

appear to spring free of the weir blade, but the weir blade was not submerged by the 

tailwater. Therefore, the weir condition is classified as partially submerged. The onset 

of weir submergence occurs at approximately 2.8 ft of head on the primary bypass weir 

when the water surface elevation in the secondary screening facility is 1213.0 ft. For 

head values greater than 2.8 ft, the weir operates in a submerged condition. 

The weir ratings for Bays 1, 3, and 5 are consistent when free flow and partially 

submerged conditions exist. The Bay 1 bypass weir shows slightly greater efficiency 

than the bypass weirs in Bays 3 and 5. This could be a result of the weir blade condition 

or a slightly higher upstream water surface elevation. During the transition from a 

partially submerged to fully submerged weir, the primary bypass weir becomes less 

efficient per incremental increase in tailwater level such that the shape of the rating 

curve changes from the standard power law relationship to a polynomial relationship. 

Under submerged conditions, the Bay 1 bypass weir becomes less efficient than Bays 3 

and 5 since the length of the bypass pipe between the primary screening bay and the 

secondary screening facility is longest, and therefore has the greatest pipe headloss. 

Rating tables, equations, and curve-fit R-squared values are given in Table 2a for data 

averaged from all primary bypasses, Table 2b for Bay 1 bypass only, Table 2c for Bay 3 

bypass only, and Table 2d for Bay 5 bypass only. Although the weir ratings are slightly 

varied, the average bypass rating equation in Table 2a should be sufficient for 

calculating primary bypass flow rates or setting bypass weirs. The developed rating 

curves can be accurately applied when the facility operates with a water surface 

elevation of 1213.0 ft in the secondary screening facility. When the water surface 

elevation is operated at 1213.8 ft during juvenile trapping, the onset of submergence can 

18
be expected to occur at a lower head value. The change to the weir rating should be

minimal. Field testing would be required to determine the extent of the change. 

The 1989 NMFS Operating Criteria recommends that the bypass weirs be set to 4.4 ft of 

head on the weir (Pearce, 1989). The weir is submerged at this setting. From the field 

ratings, the average bypass flow rate for 4.4 ft of head is 64.9 ft3

/s. This value closely 

compares to the primary bypass flow rates reported in the July 2003 evaluation. To 

achieve a reduced primary bypass flow rate of 50 ft3

/s, the bypass weirs should be set at 

3.35 ft. Like operation at 65 ft3

/s, the bypass weirs operate in a submerged condition at 

50 ft3

/s. 

19
Table 1. – Summary of primary fish bypass data collected in Bays 1, 3, and 5 with a forebay elevation of 1220.4 ft and 

elevation of 1213.0 ft in the secondary screening facility. 

Head Above Weir Crest Estimated Tailwater Operational Mean Velocity (ft/s) Mean Chann

Weir Crest (ft) Elev. (ft) Elevation (ft) Weir Condition 0.2 depth 0.8 depth Velocity (ft/s

0 1220.44 1212.88 Free flow 0.03 0.07 0.05 

0.53 1219.86 1213.22 Free flow 0.14 0.08 0.11 1.03 1219.36 1214.13 Free flow 0.29 0.35 0.32 1.53 1218.86 1215.47 Free flow 0.49 0.68 0.58 2.03 1218.36 1217.13 Partially submerged 0.77 1.18 0.97 

BAY 1 2.53 1217.86 1217.47 Partially submerged 1.47 1.56 1.51 

3.03 1217.36 1218.30 Submerged 1.91 1.96 1.94 3.53 1216.86 1218.80 Submerged 2.32 2.40 2.36 4.03 1216.36 1219.55 Submerged 2.44 2.59 2.51 4.36 1216.02 1219.63 Submerged 2.58 2.58 2.58 4.86 1215.52 1219.97 Submerged 2.74 2.76 2.75 

0 1220.40 1213.05 Free flow 0.06 0.06 0.06 

0.48 1219.90 1213.38 Free flow 0.14 0.13 0.14 0.98 1219.40 1214.22 Free flow 0.39 0.36 0.38 1.48 1218.90 1215.13 Free flow 0.57 0.53 0.55 1.98 1218.40 1216.30 Partially submerged 1.04 0.88 0.96 

BAY 3 2.48 1217.90 1216.30 Partially submerged 1.47 1.23 1.35 

2.98 1217.40 1217.47 Submerged 1.94 1.64 1.79 3.48 1216.90 1218.47 Submerged 2.31 2.14 2.23 3.98 1216.40 1219.30 Submerged 2.57 2.52 2.54 4.31 1216.07 1219.63 Submerged 2.67 2.70 2.69 4.90 1215.48 1220.05 Submerged 2.90 2.74 2.82 

0 1220.39 1213.05 Free flow 0.06 0.09 0.08 

0.41 1219.97 1213.13 Free flow 0.15 0.15 0.15 0.91 1219.47 1213.88 Free flow 0.30 0.38 0.34 1.41 1218.97 1214.97 Free flow 0.64 0.51 0.58 1.91 1218.47 1216.17 Partially submerged 0.93 0.81 0.87 

BAY 5 2.41 1217.97 1217.38 Partially submerged 1.42 1.14 1.28 

3.00 1217.39 1217.76 Submerged 1.88 1.58 1.73 3.50 1216.89 1218.26 Submerged 2.29 2.06 2.18 4.00 1216.39 1218.72 Submerged 2.61 2.48 2.54 4.37 1216.01 1219.38 Submerged 2.79 2.59 2.69 4.95 1215.43 1219.97 Submerged 3.01 2.85 2.93 
0

1020304050607080

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 

Head Above Weir Crest (ft)

Bypass Flow Rate (ft

3

/s)

Bay 1 Bypass WeirBay 3 Bypass WeirBay 5 Bypass WeirStandard Suppressed Weir RatiField Data Curve-Fit Equation

Partially Submerged Zone Submerged Zone

Q = 3.33 L H 3/2 Q = 1.5537 - 1.3761H + 8.4316H2 - 1.1012H3

R2 = 0.9982

Free Flow Zone

Figure 12. – Primary fish bypass weir rating curve. Measured field data is compared to standard suppressed rectangular w

for free flow, partially submerged, and submerged conditions. H is the head on the weir crest in feet and Q is the bypass fl
Table 2a. – Average rating table and equation for all primary bypass weirs. H is the head on the weir cr

feet and Q is the bypass flow rate in ft3/s. “---” indicates that bypass flow rate cannot be accurately e

Q = 1.5537 - 1.3761 H + 8.4316 H2 - 1.1012 H3 R2 = 0.9982 

Head Above Primary Bypass Flow Rate (ft3/s) 

Weir Crest (ft) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 

0 --- --- 1.6 1.9 2.3 2.8 3.5 4.3 5.3 1 7.5 8.8 10.1 11.6 13.1 14.7 16.4 18.2 20.0 2 23.7 25.6 27.6 29.6 31.6 33.6 35.6 37.6 39.6 3 43.6 45.5 47.4 49.3 51.1 52.8 54.5 56.1 57.7 4 60.5 61.8 62.9 64.0 64.9 65.8 66.4 67.0 67.4 

Table 2b. – Bay 1 bypass weir rating table and equation. H is the head on the weir crest in feet and Q is 

flow rate in ft3/s. “---” indicates that bypass flow rate cannot be accurately estimated.

Q = 1.2064 - 3.2817 H + 10.1719 H2 - 1.4026 H3

R2 = 0.9986 

Head Above Primary Bypass Flow Rate (ft3/s) 

Weir Crest (ft) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 

0 --- --- --- 1.1 1.4 1.9 2.6 3.4 4.4 1 6.7 8.0 9.5 11.0 12.7 14.4 16.3 18.1 20.1 2 24.1 26.2 28.3 30.4 32.5 34.7 36.8 38.9 41.0 3 45.0 47.0 48.9 50.7 52.5 54.2 55.8 57.3 58.7 4 61.1 62.1 62.9 63.7 64.2 64.6 64.8 64.9 64.7 
Table 2c. – Bay 3 bypass weir rating table and equation. H is the head on the weir crest in feet and Q is 

bypass flow rate in ft3/s. “---” indicates that bypass flow rate cannot be accurately estimated.

Q = 1.4816 - 1.3849 H + 8.4372 H2 - 1.0988 H3R2 = 0.9994 

Head Above Primary Bypass Flow Rate (ft3/s) 

Weir Crest (ft) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 

0 --- --- 1.5 1.8 2.2 2.8 3.5 4.3 5.2 1 7.4 8.7 10.1 11.5 13.1 14.7 16.4 18.1 19.9 2 23.7 25.6 27.6 29.6 31.6 33.6 35.6 37.6 39.6 3 43.6 45.5 47.4 49.3 51.1 52.9 54.6 56.2 57.8 4 60.6 61.9 63.1 64.2 65.1 66.0 66.7 67.3 67.7 

Table 2d. – Bay 5 bypass weir rating table and equation. H is the head on the weir crest in feet and Q is 

bypass flow rate in ft3/s.

Q = 1.9808 - 0.0301 H + 7.0487 H2 - 0.8611 H3R2 = 0.9996 

Head Above Primary Bypass Flow Rate (ft3/s) 

Weir Crest (ft) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 

0 2.0 2.0 2.2 2.6 3.0 3.6 4.3 5.1 6.0 1 8.1 9.3 10.6 12.0 13.4 14.9 16.5 18.1 19.7 2 23.2 25.0 26.9 28.7 30.6 32.5 34.4 36.3 38.3 3 42.1 44.0 45.8 47.7 49.5 51.3 53.0 54.7 56.4 4 59.5 61.0 62.4 63.7 65.0 66.1 67.2 68.1 69.0 
Final Fish Bypass Weirs 

Operation of the final bypass weir is subject to operational constraints. Operating criteria 

requires a minimum of 2.0 ft of head on the final bypass weir. When the water surface 

elevation in the secondary screening facility is set to the design stage of 1213.0 ft, the 

final bypass weir can only be set to a head value of 3.0 ft in order to maintain an optimal 

tailwater pool in the downwell for fish passage. Head values lower than 3.0 ft do not 

provide an adequate tailwater pool for safe fish passage. Head values greater than 3.0 

ft cannot be achieved because the weir cannot be physically lowered any farther. 

When the temporary ramp to the juvenile trap is installed, the water surface elevation in 

front of the traveling screens must be raised to 1213.8 ft to provide flow into the trapping 

facility. With the ramp installed at a water elevation of 1213.8 ft, the weir can only be set 

to a head value of 3.6 ft to maintain an optimal tailwater pool in the downwell. Like the 

previous condition, the weir cannot be physically lowered to pass higher bypass flows. 

Results of the final bypass analysis for current operational secondary water surface 

elevations of 1213.0 ft and 1213.8 ft are shown in Table 3: 

Table 3. – Final fish bypass velocities and flow rates with an optimal tailwater pool. 

Head on Velocity (ft/s) Water Bypass Flow 

Weir (ft) 0.2 depth 0.8 depth Mean Depth (ft) Rate (ft3/s) 

Water Surface 

Elev. 1213.0 ft 

No Ramp 

3.0 3.73 3.95 3.84 5.26 40.4

Water Surface 

Elev. 1213.8 ft 

With Ramp 

3.6 3.16 3.32 3.24 6.16 39.9

In August 2004, velocities in the final bypass channel were significantly higher than 

velocities measured during previous evaluations. In July 2003, the juvenile fish ramp 

was not installed and the upstream water surface elevation was set to 1213.0 ft. The 

measured flow rate was 30.0 ft3

/s. During the March 2004 evaluation, the juvenile ramp 

and trap were installed in the trapping facility with a secondary water surface elevation of 

1213.8 ft. The final bypass flow rate was calculated as 28.8 ft3

/s. 

It is unclear why this evaluation yields final bypass flow rates that are 25 percent higher 

than previous measurements. Possible explanations include bypass pipe blockage in

previous evaluations or a difference in the downwell condition set by the weir operator. 

Great care was taken during these experiments to properly set an optimal tailwater pool. 

The difference between a minimum acceptable tailwater pool and an optimal tailwater 

pool is subjective. If the weir was not set at a low enough elevation to provide for an 

optimal tailwater pool, a lower bypass flow rate would be expected. 

Drum Screens 

Velocity Measurements with Primary Bypass Flows of 65 ft3

/s

Detailed lateral and vertical velocity distributions across the drum screens are displayed 

in Figures 13-18 and Figures II-1 and II-2 in Appendix II. Figures 13a-18a show the 

sweep and approach velocity distributions for the operating fish bypass weir setting of 

4.4 ft of head (approximately 65 ft3

/s per bay). Figures 13a, 14a, and 15a show velocity 

24
data in Bay 2 on Screens 20, 18 and 17, respectively. Figures 16a, 17a, and 18a show

velocity data in Bay 5 on Screens 5, 3, and 2, respectively. Approach velocities 

measured in Bay 2 at 0.05 times the water depth were sufficiently represented by 

measurements at 0.2 and 0.5 times the depth (Figures 13a, 14a, and 15a). Therefore, 

these near-surface measurements were not collected for all conditions. Approach 

velocities measured at 0.8 times the water depth were typically higher than velocities 

measured at 0.2 and 0.5. 

Approach velocities measured at 0.9 times the water depth were significantly higher than 

velocities measured at shallower depths. Velocities at 0.9 times the depth also 

contained higher downward vertical velocity components than velocity measurements at 

other depths (Appendix I). Vertical velocity components were not included in figures for 

clarity. The forebay floor drops from elevation 1208.39 ft in front of the drum screens to 

elevation 1207.35 ft at the drum screen seat (Figure 8). Sluice gates installed in the 

stoplog slots behind the drum screens were placed 1 ft from the channel bottom to 

promote sediment movement past the screens and 1 ft from the water surface to allow 

debris and flow to pass over the boards. It is likely that both the recessed floor in front of 

the drum screens and the placement of the sluice gates contribute to high approach and 

downward velocities near the drum screens at the bottom of the water column. 

Table 4 shows the percent of measurement locations that exceed the current NOAA fish 

screen approach velocity criteria of 0.4 ft/s and the facility design criteria of 0.5 ft/s. At 

the operating criteria of 4.4 ft of head on the primary bypass weirs, the approach 

velocities in Bay 5 are generally higher than the approach velocities in Bay 2 and exceed 

criteria more frequently. Approach velocities measured at depths below the curvature of 

the screen (0.8 and 0.9 depths) exceed criteria more frequently than shallower 

measurements. Approach velocities exceed the 0.4 ft/s NOAA criteria at 75 percent of

189 total measurement locations and 100 percent of locations at the deepest 

measurement depth. Approach velocities exceed the 0.5 ft/s design criteria at 58 

percent of 189 total measurement locations and 100 percent of locations at the deepest 

measurement depth. 

Sweep velocity magnitudes were similar between Bays 2 and 5. Sweep velocities do not 

exhibit a clear acceleration along the screens into the fish bypass channel. Table 5 

shows the percent of measurement locations where the sweep-to-approach velocity ratio 

is less than the current NOAA screen criteria. NOAA requires a 1:1 sweep-to-approach 

velocity ratio and strongly advocates a 2:1 sweep-to-approach ratio (NOAA draft, 2004). 

On all screens, several locations have sweep-to-approach velocity ratios of less than

2:1. Since sweep velocities were often lowest at the 0.9 depth and approach velocities

were often highest, ratios were less than criteria on all screens. At the operating criteria 

of 4.4 ft of head on the primary bypass weirs, 49 percent of 189 total measurement 

locations and 100 percent of locations at the deepest measurement depth have sweepto-approach velocity ratios less than 2:1. For data collected only in Bay 5, 73 percent of 

84 total measurement locations and 100 percent of locations at the deepest 

measurement depth have sweep-to-approach velocity ratios less than 2:1. For data 

collected only in Bay 2, 30 percent of 105 total measurement locations and 100 percent 

of locations at the deepest measurement depth have sweep-to-approach velocity ratios 

less than 2:1. 

25
Velocity distributions across the screens are nonuniform. NOAA fish passage criterion 

(Section 16) specifies that a uniform approach velocity is achieved when no individual 

velocity measurement exceeds 110% of the 0.4 ft/s criteria, or 0.44 ft/s. In this 

evaluation, approach velocities exceed the 0.5 ft/s criteria at all depths on Screens 2, 3, 

5, and 20 and at some depths on Screens 17 and 18. Approach and sweep velocities

are highest and least uniform on the most upstream screen in each bay (Screen 20 for 

Bay 2 and Screen 5 for Bay 5). The highest velocities on these screens occur at the

most upstream measurement location (Figures II-1 to II-4 in Appendix II). Approach and 

sweep velocities are more consistent vertically and laterally across screens in the center 

of the bays (Screens 18 and 17 in Bay 2 and Screens 3 and 2 in Bay 5). Generally, 

approach and sweep velocities are slightly higher at the leading edge of each screen 

and slightly lower at the trailing edge of the screen. The concrete support piers between 

screens may be a factor in this variability. 

Velocity Measurements with Primary Bypass Flows of 50 ft3

/s 

Figures 13b, 14b, 15b, 16b, 17b, and 18b and Figures II-1 and II-2 in Appendix II show 

velocities measured at a primary bypass flow rate of 50 ft3

/s per bay. In Appendix II, 

Figures II-3 to II-6 show velocity patterns for each screen with iso-velocity lines. When 

the primary bypass flow rate is reduced from 65 to 50 ft3

/s, approach velocity 

magnitudes in Bay 2 exceed design criteria more frequently, while approach velocities in 

Bay 5 do not change considerably (Table 4). Approach velocities exceed 0.4 ft/s at 92 

percent of 168 measurement locations. 

In Bays 2 and 5, sweep velocities decrease. At a bypass flow rate of 50 ft3

/s, sweep-toapproach velocity ratios are less than 2:1 for 82 percent of all measurement locations, as 

compared to 49 percent of all measurement locations when the bypass flow rate is 65

ft3

/s. The effect of reducing the bypass flow rate is clearly illustrated in Figure 19 for Bay 

2 and Figure 20 for Bay 5. At both 65 and 50 ft3

/s bypass flows, lateral and vertical 

velocity distributions are nonuniform and flow does not accelerate into the bypass 

intakes. 

In 2003, Battelle measured velocities in Bays 2 and 5 at bypass flow rates of 65 and 32

ft3

/s (McMichael et al., 2003). At approximately 65 ft3/s, Battelle documented high 

approach velocities with large vertical and lateral variations over the screen faces in Bay 

5. Approach velocities were lower and less variable in Bay 2. This hydraulic evaluation 

shows a similar pattern at a similar bypass flow rate. When Battelle reduced the bypass 

flow rate to 32 ft3

/s, Bay 2 sweep velocities decreased and approach velocities 

increased. In Bay 5, the opposite occurred. This evaluation shows a similar trend to the 

data collected in Bay 2, but not Bay 5. 

26
BAY 2, SCREEN 20 

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10

Location Across Screen (ft)

Velocity (ft/s)

12

0.05 depth - Va

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.05 depth - Vs

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - Vs

NOAA Screen Criteria

Facility Design Criteria

Figure 13a. – Sweep (Vs) and approach (Va) velocity distributions on Screen 20 at a Bay 2 fish 

bypass weir setting of 4.4 ft of head (approximately 65 ft3/s). 

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10

Location Across Screen (ft)

Velocity (ft/s)

12

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - Vs

NOAA Screen Criteria

Facility Design Criteria

Figure 13b. - Sweep (Vs) and approach (Va) velocity distributions on Screen 20 at a Bay 2 fish 

bypass flow rate of 50 ft3/s. 

27
BAY 2, SCREEN 18 

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10

Location Across Screen

12

(ft)

Velocity (ft/s)

0.05 depth - Va

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.05 depth - Vs

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - Vs

NOAA Screen Criteria

Facility Design Criteria

Figure 14a. – Sweep (Vs) and approach (Va) velocity distributions on Screen 18 at a Bay 2 

primary bypass weir setting of 4.4 ft of head (approximately 65 ft3/s).

0

0.5

1

1.5

2

2.5

024 6 8 10

Location Across Screen (ft)

Velocity (ft/s)

12

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - Vs

NOAA Screen Criteria

Facility Design Criteria

Figure 14b. – Sweep (Vs) and approach (Va) velocity distributions on Screen 18 at a Bay 2 

primary bypass flow rate of 50 ft3

/s. 

28
BAY 2, SCREEN 17

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10

Location Across Screen 

12

(ft)

Velocity (ft/s)

0.05 depth - Va

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.05 depth - Vs

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - Vs

NOAA Screen Criteria

Facility Design Criteria

Figure 15a. – Sweep (Vs) and approach (Va) velocity distributions on Screen 17 at a Bay 2 

primary bypass weir setting of 4.4 ft of head (approximately 65 ft3/s).

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10

Location Across Screen (ft)

Velocity (ft/s)

12

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - Vs

NOAA Screen Criteria

Facility Design Criteria

Figure 15b. – Sweep (Vs) and approach (Va) velocity distributions on Screen 17 at a Bay 2 

primary bypass flow rate of 50 ft3

/s. 

29
BAY 5, SCREEN 5 

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10 12

Location Across Screen (ft)

Velocity (ft/s)

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - Vs

NOAA Screen Criteria

Facility Design Criteria

Figure 16a. – Sweep (Vs) and approach (Va) velocity distributions on Screen 5 at a Bay 5 primary 

bypass weir setting of 4.4 ft of head (approximately 65 ft3/s). 

0

0.5

1

1.5

2

2.5

024 6 8 10

Location Across Screen (ft)

Velocity (ft/s)

12

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - Vs

NOAA Screen Criteria

Facility Design Criteria

Figure 16b. – Sweep (Vs) and approach (Va) velocity distributions on Screen 5 at a Bay 5 primary 

bypass flow rate of 50 ft3/s. 

30
BAY 5, SCREEN 3 

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10

Location Across Screen (ft)

Velocity (ft/s)

12

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - Vs

NOAA Screen Criteria

Facility Design Criteria

Figure 17a. – Sweep (Vs) and approach (Va) velocity distributions on Screen 3 at a Bay 5 primary 

bypass weir setting of 4.4 ft of head (approximately 65 ft3/s). 

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10

Location Across Screen (ft)

Velocity (ft/s)

12

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - Vs

NOAA Screen Criteria

Facility Design Criteria

Figure 17b. – Sweep (Vs) and approach (Va) velocity distributions on Screen 3 at a Bay 5 primary 

bypass flow rate of 50 ft3

/s. 

31
BAY 5, SCREEN 2 

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10 12

Location Across Screen (ft)

Velocity (ft/s)

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - Vs

NOAA Screen Criteria

Facility Design Criteria

Figure 18a. – Sweep (Vs) and approach (Va) velocity distributions on Screen 2 at a Bay 5 primary 

bypass weir setting of 4.4 ft of head (approximately 65 ft3/s). 

0

0.5

1

1.5

2

2.5

0 2 4 6 8 10

Location Across Screen (ft)

Velocity (ft/s)

12

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - Vs

NOAA Screen Criteria

Facility Design Criteria

Figure 18b. – Sweep (Vs) and approach (Va) velocity distributions on Screen 2 at a Bay 5 primary 

bypass flow rate of 50 ft3

/s.

32
Table 4. - Percentage of 7 lateral measurement locations where approach velocity (Va) measurements exceed NOAA criter

facility design criteria of 0.5 ft/s. 

Bypass Flow Rate = 65 ft3/s 

SCREENING BAY 2 SCREENING BAY 5 

Screen 20 Screen 18 Screen 17 Screen 5 Screen 3 

Depth 

Va > 0.4 

ft/s

Va > 0.5 

ft/s

Va > 0.4 

ft/s

Va > 0.5 

ft/s

Va > 0.4 

ft/s

Va > 0.5 

ft/s

Va > 0.4 

ft/s

Va > 0.5 

ft/s

Va > 0.4 

ft/s

Va > 0.5 

ft/s

Va > 

ft/s

0.05 71% 43% 14% 0% 29% 0% -- -- -- -- -- 

0.2 86% 43% 29% 0% 57% 0% 86% 86% 86% 71% 86% 0.5 57% 14% 0% 0% 0% 0% 86% 86% 86% 86% 86% 0.8 86% 86% 100% 43% 71% 0% 100% 86% 100% 86% 1000.9 100% 100% 100% 100% 100% 100% 100% 100% 100% 100% 100

Bypass Flow Rate = 50 ft3/s 

SCREENING BAY 2 SCREENING BAY 5 

Screen 20 Screen 18 Screen 17 Screen 5 Screen 3 

Depth 

Va > 0.4 

ft/s

Va > 0.5 

ft/s

Va > 0.4 

ft/s

Va > 0.5 

ft/s

Va > 0.4 

ft/s

Va > 0.5 

ft/s

Va > 0.4 

ft/s

Va > 0.5 

ft/s

Va > 0.4 

ft/s

Va > 0.5 

ft/s

Va > 

ft/s

0.05 -- -- -- -- -- -- -- -- -- -- -- 

0.2 86% 71% 86% 29% 86% 43% 86% 86% 86% 86% 86% 0.5 86% 86% 86% 71% 86% 71% 86% 86% 86% 86% 86% 0.8 86% 86% 100% 86% 86% 57% 100% 86% 100% 100% 1000.9 100% 100% 100% 100% 100% 100% 100% 86% 100% 100% 100
Table 5. – Percentage of 7 lateral measurement locations where the sweep-to-approach velocity ratio (Vs/Va) does not mee

Bypass Flow Rate = 65 ft3/s 

SCREENING BAY 2 SCREENING BAY 5 

Screen 20 Screen 18 Screen 17 Screen 5 Screen 3 

Depth 

Vs/Va

< 1:1 

Vs/Va

< 2:1 

Vs/Va

< 1:1 

Vs/Va

< 2:1 

Vs/Va

< 1:1 

Vs/Va

< 2.1 

Vs/Va

< 1:1 

Vs/Va

< 2.1 

Vs/Va

< 1:1 

Vs/Va

< 2:1 

Vs/V

< 1

0.05 14% 29% 0% 0% 0% 0% -- -- -- -- -- 

0.2 0% 0% 0% 14% 0% 0% 0% 14% 0% 43% 0% 0.5 0% 0% 0% 0% 0% 0% 0% 86% 0% 71% 0% 0.8 0% 57% 0% 43% 0% 0% 0% 100% 0% 86% 0% 0.9 71% 100% 14% 100% 0% 100% 57% 100% 29% 100% 14% 

Bypass Flow Rate = 50 ft3/s 

SCREENING BAY 2 SCREENING BAY 5 

Screen 20 Screen 18 Screen 17 Screen 5 Screen 3 

Depth 

Vs/Va

< 1:1 

Vs/Va

< 2:1 

Vs/Va

< 1:1 

Vs/Va

< 2:1 

Vs/Va

< 1:1 

Vs/Va

< 2:1 

Vs/Va

< 1:1 

Vs/Va

< 2:1 

Vs/Va

< 1:1 

Vs/Va

< 2:1 

Vs/V

< 1

0.05 -- -- -- -- -- -- -- -- -- -- -- 

0.2 0% 0% 0% 71% 0% 14% 0% 71% 0% 57% 0% 0.5 0% 86% 0% 86% 0% 86% 0% 86% 0% 86% 0% 0.8 0% 100% 0% 100% 0% 71% 43% 100% 29% 100% 14% 0.9 43% 100% 57% 100% 0% 100% 29% 100% 14% 100% 14% 
0

1

2

3

4

5

6

7

8

0.5 2468 10 11.5 0.5 2 4 6 8 10 11.5 0.5 2468 10 11.5

Sweep-to-Approach Velocity Ratio

0.05 depth, 65 ft3/s bypass

0.2 depth, 65 ft3/s bypass

0.2 depth, 50 ft3/s bypass

0.5 depth, 65 ft3/s bypass

0.5 depth, 50 ft3/s bypass

0.8 depth, 65 ft3/s bypass

0.8 depth, 50 ft3/s bypass

0.9 depth, 65 ft3/s bypass

0.9 depth, 50 ft3/s bypass

NOAA Sweep Velocity Criteria

NOAA Target Sweep Velocity Ratio

SCREEN 20 Location (ft) PIER SCREEN 18 Location (ft) PIER SCREEN 17 Location (ft)

Figure 19. - Ratio of sweep-to-approach velocity in front of Bay 2 screens. 

0

1

2

3

4

5

6

7

8

0.5 2468 10 11.5 0.5 2468 10 11.5 0.5 2 468 10 11.5

Sweep-to-Approach Velocity Ratio

0.2 depth, 65 ft3/s bypass

0.2 depth, 50 ft3/s bypass

0.5 depth, 65 ft3/s bypass

0.5 depth, 50 ft3/s bypass

0.8 depth, 65 ft3/s bypass

0.8 depth, 50 ft3/s

0.9 depth, 65 ft3/s bypass

0.9 depth, 50 ft3/s bypass

NOAA Sweep Velocity Criteria

NOAA Target Sweep Velocity Ratio

SCREEN 5 Location (ft) PIER SCREEN 3 Location (ft) PIER SCREEN 2 Location (ft)

Figure 20. - Ratio of sweep-to-approach velocity in front of Bay 5 screens. 

35
RECOMMENDATIONS 

The general weir rating table or equation developed from this evaluation should be used 

to calculate primary bypass flow rates and set bypass weirs when the forebay water 

surface elevation is 1220.4 ft and the secondary water surface elevation is 1213.0 ft. 

The transition between a partially submerged and submerged weir condition should 

occur at a lower head value when the secondary water surface elevation is set to 1213.8 

ft during juvenile trapping. Field testing would be required to quantify the extent of this 

change on the weir rating. The standard suppressed rectangular weir equation should 

not be used to set bypass weirs since the adjustable bypass weirs at the facility do not 

satisfy requirements for application of the equation. 

Velocities should be collected near to the drum screens at vertical locations of 0.2, 0.5, 

0.8, and 0.9 times the water depth to describe the range of velocities over the water 

column. Since velocities collected at 0.05 times the water depth were well represented

by measurements at 0.2 and 0.5 times the depth, near-surface velocity measurements 

are not necessary at the Roza drum screens. Velocities collected at 0.9 times the water 

depth represent the higher velocities present at the bottom of the water column, 

particularly when sluice gates are installed. 

Velocities should be collected laterally near to the concrete divider piers at 0.5 ft and 

11.5 ft from the leading edge of the screen. Measuring velocities at three to five other 

lateral locations across the drum screen face is recommended to show how velocities 

vary over smaller grid sections. Since flow patterns across the screen face are well 

defined by seven locations, measuring more locations will most likely not improve 

knowledge of flow behavior. 

The costs and benefits of altering high canal flow operations by reducing the primary 

bypass flow rate should be carefully considered by fisheries biologists and facility 

managers. A primary bypass flow reduction from 65 ft3

/s to 50 ft3/s produces less 

desirable flow conditions at the drum screens as indicated by an increase in the number 

of measurement locations that exceed criteria. At 50 ft3

/s, the primary bypass weirs still 

operate in a submerged condition which does not provide much benefit for improving 

passage of downstream-migrating salmon. 

During the May 2004 hydraulic evaluation at a canal flow rate of 820 ft3

/s, the influence 

of the sluice gates on drum screen performance at 0.2 and 0.8 times the water depth 

was neutral, or even favorable. During this evaluation at a canal flow rate of 1911 ft3

/s, 

velocities collected closer to the bed at 0.9 times the water depth were higher than 

velocities at shallower depths and exceeded criteria more frequently. Since this 

evaluation included only velocity measurements with sluice gates installed, the effect of 

the sluice gates on drum screen performance under these conditions is not known. 

However, sluice gates were installed at the facility to reduce sediment build-up in front of 

the screens by increasing near-bed velocities. By improving sediment movement, it is 

likely that the increased near-bed velocities impact drum screen performance at the 

deepest locations of the screen. 

Since equipment access to measurement locations below the curvature of the drum 

screens is difficult and numerous measurement locations are needed to fully define 

velocity fields with and without sluice gates, the effect of the sluice gates on screen 

performance is not fully described through field evaluations. Numerical modeling of the 

36
Roza drum screens is strongly recommended. Numerical modeling should provide a 

clear visualization of flow conditions near to the screens including the effects of the 

sluice gates and recessed floor on the flow field. In the model, the sluice gates can be

raised or lowered to identify a configuration that balances sediment movement with 

reasonable flow conditions near the screen face. To accomplish this, a sediment 

analysis may need to be conducted. The sluice gates can be repositioned, resized, 

removed, or redesigned with a different material in the model. Numerical modeling 

should be less time consuming and less expensive than full-scale field evaluations for 

various sluice gate configurations. 

37
38

REFERENCES 

Abernathy, C. Scott, Duane A. Neitzel, and E. William Lusty (1989). “Velocity 

Measurements at Six Fish Screening Facilities in the Yakima River Basin, Summer 

1988, Annual Report.” Pacific Northwest National Laboratory, Portland, Oregon. 

Abernathy, C. Scott, Duane A. Neitzel, and E. William Lusty (1990). “Velocity 

Measurements at Three Fish Screen Facilities in the Yakima River Basin, Washington, 

Summer 1989.” Pacific Northwest National Laboratory, Portland, Oregon. 

Blanton, S.L., G.A. McMichael, and D.A. Neitzel (1998). “Washington Phase II Fish 

Diversion Screen Evaluations in the Yakima River Basin, 1997.” Pacific Northwest 

National Laboratory, Portland, Oregon. 

Blanton, S.L., D.A. Neitzel, and C.S. Abernathy (1999). “Washington Phase II Fish 

Diversion Screen Evaluations in the Yakima River Basin, 1998.” Pacific Northwest 

National Laboratory, Portland, Oregon. 

Bureau of Reclamation (2001). “Water Measurement Manual – Third Edition.” U.S. 

Department of Interior, Bureau of Reclamation, Water Resources Technical Publication, 

Denver, Colorado. 

Carter, J.A., G.A. McMichael, and M.A. Chamness (2002). “Yakima River Basin Phase II 

Fish Screen Evaluations, 2001.” Pacific Northwest National Laboratory, Portland, 

Oregon. 

Chamness, M.A., E.V. Arntzen, G.A. McMichael, and P.S. Titzler (2001). “Washington 

Phase II Fish Diversion Screen Evaluations in the Yakima River Basin, 2000.” Pacific 

Northwest National Laboratory, Portland, Oregon. 

DeMoyer, C.D. and T.B. Vermeyen (2004). “Roza Fish Screens Facility Velocity 

Measurements With and Without Porosity Boards at an Intermediate Canal Flow Rate.” 

Report No. PAP-928. Bureau of Reclamation, Water Resources Research Laboratory, 

Denver, Colorado. 

McMichael, G.A., J.A. Vucelick, and C.S. Abernathy (2003). “Roza Dam Fish Screen 

Evaluations, Summer 2003.” Battelle-Pacific Northwest Division, Richland, WA. 

National Oceanic and Atmospheric Administration (2004). “Anadromous Salmonid 

Passage Facility Guidelines and Criteria – February 2004 External Review Draft.” 

National Oceanic and Atmospheric Administration, Northwest Region, Portland, Oregon. 

Pearce, R. (1989). Operating Criteria: Roza Canal Fish Screens Bypass System. 

National Marine Fisheries Service, Northwest Region, Portland, Oregon. 
APPENDIX I: Velocity Measurements at Drum Screens 
BAY 2, SCREEN 20, Bypass Flow Rate = 65 cfs 

Velocity data collected with bypass weirs set to the design bypass flow rate at 4.4 ft head. 

Measurement Distance from Approach Velocity Sweep Velocity Vertical Velocity 

Depth Upstream Edge Toward Screen Toward Bypass Downward 

(fraction of total) of Screen (ft) (ft/s) (ft/s) (ft/s) 

0.05 0 -0.073 -0.011 -0.069 

0.05 2 1.263 1.342 -0.127 

0.05 4 0.696 1.493 -0.051 

0.05 6 0.521 1.492 -0.012 

0.05 8 0.468 1.524 -0.002 

0.05 10 0.418 1.448 -0.003 

0.05 12 0.189 1.133 0.003 

0.2 0 0.802 1.811 0.178 

0.2 2 0.739 1.533 -0.010 

0.2 4 0.616 1.537 0.016 

0.2 6 0.499 1.476 0.058 

0.2 8 0.452 1.424 0.083 

0.2 10 0.408 1.313 0.116 

0.2 12 0.194 1.057 0.162 

0.5 0.5 0.524 1.885 0.244 

0.5 2 0.482 1.814 0.275 

0.5 4 0.417 1.592 0.242 

0.5 6 0.352 1.521 0.216 

0.5 8 0.339 1.415 0.212 

0.5 10 0.274 1.210 0.148 

0.5 11.5 0.182 1.059 0.134 

0.8 0.5 0.787 2.037 0.243 

0.8 2 0.980 2.014 0.348 

0.8 4 0.959 1.659 0.411 

0.8 6 0.799 1.263 0.384 

0.8 8 0.694 1.211 0.280 

0.8 10 0.518 1.006 0.187 

0.8 11.5 0.365 1.034 0.139 

0.9 0.5 1.658 1.469 0.491 

0.9 2 1.633 1.362 0.520 

0.9 4 1.311 1.044 0.498 

0.9 6 1.087 0.868 0.366 

0.9 8 0.988 0.893 0.268 

0.9 10 0.742 0.833 0.214 

0.9 11.5 0.662 0.921 0.209 
BAY 2, SCREEN 18, Bypass Flow Rate = 65 cfs 

Velocity data collected with bypass weirs set to the design bypass flow rate at 4.4 ft head. 

Measurement Distance from Approach Velocity Sweep Velocity Vertical Velocity 

Depth Upstream Edge Toward Screen Toward Bypass Downward 

(fraction of total) of Screen (ft) (ft/s) (ft/s) (ft/s) 

0.05 0 0.414 1.629 0.146 

0.05 2 0.365 1.120 0.011 

0.05 4 0.297 1.200 -0.012 

0.05 6 0.315 1.117 -0.018 

0.05 8 0.332 1.159 -0.002 

0.05 10 0.337 0.915 0.005 

0.05 12 0.111 0.515 -0.012 

0.2 0 0.413 1.229 0.107 

0.2 2 0.386 1.168 0.098 

0.2 4 0.393 0.944 0.025 

0.2 6 0.397 0.989 0.048 

0.2 8 0.406 0.930 0.071 

0.2 10 0.365 0.673 0.029 

0.2 12 0.148 0.642 -0.007 

0.5 0.5 0.352 1.040 0.040 

0.5 2 0.310 1.039 -0.010 

0.5 4 0.331 1.035 0.076 

0.5 6 0.300 0.981 0.029 

0.5 8 0.346 0.995 0.103 

0.5 10 0.330 1.013 0.110 

0.5 11.5 0.228 0.942 0.148 

0.8 0.5 0.441 1.058 0.082 

0.8 2 0.492 1.032 0.044 

0.8 4 0.514 0.958 0.100 

0.8 6 0.510 0.954 0.100 

0.8 8 0.515 0.954 0.111 

0.8 10 0.470 0.949 0.143 

0.8 11.5 0.425 1.002 0.196 

0.9 0.5 0.866 0.914 0.095 

0.9 2 0.750 0.838 0.155 

0.9 4 0.831 0.815 0.126 

0.9 6 0.842 0.868 0.150 

0.9 8 0.778 0.788 0.160 

0.9 10 0.767 0.859 0.192 

0.9 11.5 0.778 0.971 0.222 
BAY 2, SCREEN 17, Bypass Flow Rate = 65 cfs 

Velocity data collected with bypass weirs set to the design bypass flow rate at 4.4 ft head. 

Measurement Distance from Approach Velocity Sweep Velocity Vertical Velocity 

Depth Upstream Edge Toward Screen Toward Bypass Downward 

(fraction of total) of Screen (ft) (ft/s) (ft/s) (ft/s) 

0.05 0 0.456 1.326 0.024 

0.05 2 0.397 1.158 -0.015 

0.05 4 0.410 1.037 -0.008 

0.05 6 0.383 1.005 0.007 

0.05 8 0.358 1.090 -0.015 

0.05 10 0.393 1.039 0.019 

0.05 12 0.145 0.710 -0.017 

0.2 0 0.370 1.313 0.085 

0.2 2 0.425 1.140 0.065 

0.2 4 0.423 1.069 0.069 

0.2 6 0.414 1.183 0.083 

0.2 8 0.427 1.090 0.098 

0.2 10 0.345 0.931 0.098 

0.2 12 0.088 0.923 0.021 

0.5 0.5 0.306 1.347 0.126 

0.5 2 0.284 1.254 0.128 

0.5 4 0.288 1.087 0.137 

0.5 6 0.280 1.159 0.118 

0.5 8 0.246 1.058 0.076 

0.5 10 0.240 0.937 0.045 

0.5 11.5 0.157 0.845 0.119 

0.8 0.5 0.446 1.147 0.113 

0.8 2 0.465 1.126 0.101 

0.8 4 0.478 1.045 0.108 

0.8 6 0.439 1.051 0.070 

0.8 8 0.461 1.057 0.062 

0.8 10 0.381 0.961 0.085 

0.8 11.5 0.317 1.020 0.154 

0.9 0.5 0.850 0.932 0.191 

0.9 2 0.926 1.034 0.179 

0.9 4 0.806 0.873 0.172 

0.9 6 0.766 0.835 0.163 

0.9 8 0.767 0.796 0.124 

0.9 10 0.667 0.830 0.148 

0.9 11.5 0.622 0.932 0.173 
BAY 2, SCREEN 20, Bypass Flow Rate = 50 cfs 

Velocity data collected with a bypass flow rate of 50 cfs. 

Measurement Distance from Approach Velocity Sweep Velocity Vertical Velocity 

Depth Upstream Edge Toward Screen Toward Bypass Downward 

(fraction of total) of Screen (ft) (ft/s) (ft/s) (ft/s) 

0.2 0.5 0.834 1.717 0.017 

0.2 2 0.737 1.501 -0.018 

0.2 4 0.629 1.387 0.026 

0.2 6 0.543 1.297 0.004 

0.2 8 0.516 1.302 0.059 

0.2 10 0.414 1.074 0.077 

0.2 11.5 0.268 0.996 0.073 

0.5 0.5 0.965 1.429 0.225 

0.5 2 0.922 1.371 0.212 

0.5 4 0.876 1.240 0.243 

0.5 6 0.775 1.053 0.224 

0.5 8 0.658 0.886 0.209 

0.5 10 0.591 0.957 0.152 

0.5 11.5 0.345 0.748 0.157 

0.8 0.5 1.047 1.974 0.390 

0.8 2 1.210 1.664 0.450 

0.8 4 1.110 1.356 0.509 

0.8 6 0.903 1.102 0.424 

0.8 8 0.705 0.764 0.255 

0.8 10 0.500 0.616 0.228 

0.8 11.5 0.397 0.728 0.211 

0.9 0.5 1.463 1.596 0.409 

0.9 2 1.596 1.384 0.545 

0.9 4 1.395 1.115 0.516 

0.9 6 1.074 0.980 0.373 

0.9 8 0.946 0.984 0.293 

0.9 10 0.810 0.890 0.221 

0.9 11.5 0.649 0.959 0.219 
BAY 2, SCREEN 18, Bypass Flow Rate = 50 cfs 

Velocity data collected with a bypass flow rate of 50 cfs. 

Measurement Distance from Approach Velocity Sweep Velocity Vertical Velocity 

Depth Upstream Edge Toward Screen Toward Bypass Downward 

(fraction of total) of Screen (ft) (ft/s) (ft/s) (ft/s) 

0.2 0.5 0.437 1.107 0.027 

0.2 2 0.449 0.763 0.058 

0.2 4 0.294 0.666 0.041 

0.2 6 0.503 0.962 0.044 

0.2 8 0.483 0.907 0.000 

0.2 10 0.526 0.876 0.021 

0.2 11.5 0.464 0.783 0.005 

0.5 0.5 0.539 0.962 0.057 

0.5 2 0.518 0.845 0.004 

0.5 4 0.627 0.901 0.114 

0.5 6 0.667 0.968 0.161 

0.5 8 0.619 0.931 0.129 

0.5 10 0.487 0.781 0.148 

0.5 11.5 0.353 0.980 0.191 

0.8 0.5 0.507 0.919 0.141 

0.8 2 0.554 0.985 0.157 

0.8 4 0.734 0.982 0.172 

0.8 6 0.759 0.987 0.188 

0.8 8 0.633 0.916 0.183 

0.8 10 0.562 0.876 0.191 

0.8 11.5 0.472 0.939 0.215 

0.9 0.5 0.778 0.789 0.099 

0.9 2 0.888 0.820 0.181 

0.9 4 0.834 0.762 0.134 

0.9 6 0.864 0.772 0.165 

0.9 8 0.833 0.745 0.159 

0.9 10 0.779 0.826 0.210 

0.9 11.5 0.745 0.938 0.223 
BAY 2, SCREEN 17, Bypass Flow Rate = 50 cfs 

Velocity data collected with a bypass flow rate of 50 cfs. 

Measurement Distance from Approach Velocity Sweep Velocity Vertical Velocity 

Depth Upstream Edge Toward Screen Toward Bypass Downward 

(fraction of total) of Screen (ft) (ft/s) (ft/s) (ft/s) 

0.2 0.5 0.459 1.304 0.088 

0.2 2 0.522 1.173 0.050 

0.2 4 0.508 1.116 0.087 

0.2 6 0.509 1.065 0.047 

0.2 8 0.441 0.960 0.055 

0.2 10 0.421 0.763 0.083 

0.2 11.5 0.237 0.760 0.064 

0.5 0.5 0.752 1.104 0.140 

0.5 2 0.699 0.994 0.088 

0.5 4 0.671 0.974 0.069 

0.5 6 0.645 0.898 0.082 

0.5 8 0.631 0.899 0.085 

0.5 10 0.441 0.840 0.109 

0.5 11.5 0.388 0.989 0.134 

0.8 0.5 0.567 1.057 0.185 

0.8 2 0.628 1.097 0.159 

0.8 4 0.552 1.006 0.188 

0.8 6 0.553 0.882 0.132 

0.8 8 0.481 0.818 0.144 

0.8 10 0.438 0.968 0.129 

0.8 11.5 0.350 0.936 0.157 

0.9 0.5 0.883 1.030 0.183 

0.9 2 0.886 1.010 0.166 

0.9 4 0.835 0.947 0.132 

0.9 6 0.815 0.966 0.125 

0.9 8 0.761 0.873 0.116 

0.9 10 0.667 0.854 0.164 

0.9 11.5 0.646 0.964 0.161 
BAY 5, SCREEN 5, Bypass Flow Rate = 65 cfs 

Velocity data collected with bypass weirs set to the design bypass flow rate at 4.4 ft head. 

Measurement Distance from Approach Velocity Sweep Velocity Vertical Velocity 

Depth Upstream Edge Toward Screen Toward Bypass Downward 

(fraction of total) of Screen (ft) (ft/s) (ft/s) (ft/s) 

0.2 0.5 0.882 1.704 0.033 

0.2 2 0.824 1.654 0.000 

0.2 4 0.772 1.595 0.067 

0.2 6 0.683 1.463 0.096 

0.2 8 0.658 1.431 0.104 

0.2 10 0.571 1.273 0.086 

0.2 11.5 0.297 1.155 0.056 

0.5 0.5 0.934 1.554 0.347 

0.5 2 0.882 1.471 0.329 

0.5 4 0.847 1.265 0.336 

0.5 6 0.729 1.126 0.370 

0.5 8 0.661 1.026 0.333 

0.5 10 0.500 0.762 0.348 

0.5 11.5 0.363 0.870 0.158 

0.8 0.5 0.922 1.834 0.283 

0.8 2 1.282 1.771 0.442 

0.8 4 1.163 1.392 0.519 

0.8 6 0.948 1.192 0.414 

0.8 8 0.822 0.990 0.265 

0.8 10 0.555 0.785 0.284 

0.8 11.5 0.455 0.826 0.214 

0.9 0.5 1.436 1.512 0.306 

0.9 2 1.620 1.330 0.472 

0.9 4 1.390 1.100 0.500 

0.9 6 1.020 0.878 0.350 

0.9 8 0.877 0.855 0.293 

0.9 10 0.739 0.833 0.222 

0.9 11.5 0.559 0.906 0.225 
BAY 5, SCREEN 3, Bypass Flow Rate = 65 cfs 

Velocity data collected with bypass weirs set to the design bypass flow rate at 4.4 ft head. 

Measurement Distance from Approach Velocity Sweep Velocity Vertical Velocity 

Depth Upstream Edge Toward Screen Toward Bypass Downward 

(fraction of total) of Screen (ft) (ft/s) (ft/s) (ft/s) 

0.2 0.5 0.553 1.407 0.145 

0.2 2 0.524 1.194 0.096 

0.2 4 0.467 0.991 0.051 

0.2 6 0.535 0.962 0.034 

0.2 8 0.510 0.843 0.046 

0.2 10 0.537 0.849 0.126 

0.2 11.5 0.316 0.876 0.037 

0.5 0.5 0.501 1.004 0.047 

0.5 2 0.520 0.860 0.031 

0.5 4 0.554 0.882 0.101 

0.5 6 0.562 0.870 0.097 

0.5 8 0.620 0.902 0.091 

0.5 10 0.588 0.879 0.109 

0.5 11.5 0.351 0.888 0.146 

0.8 0.5 0.577 1.106 0.081 

0.8 2 0.611 0.996 0.102 

0.8 4 0.598 0.888 0.098 

0.8 6 0.654 0.950 0.107 

0.8 8 0.660 0.934 0.135 

0.8 10 0.588 0.896 0.158 

0.8 11.5 0.464 0.942 0.188 

0.9 0.5 0.754 1.028 0.125 

0.9 2 0.784 0.895 0.096 

0.9 4 0.808 0.865 0.145 

0.9 6 0.858 0.831 0.170 

0.9 8 0.871 0.809 0.196 

0.9 10 0.746 0.766 0.207 

0.9 11.5 0.695 0.915 0.188 
BAY 5, SCREEN 2, Bypass Flow Rate = 65 cfs 

Velocity data collected with bypass weirs set to the design bypass flow rate at 4.4 ft head. 

Measurement Distance from Approach Velocity Sweep Velocity Vertical Velocity

Depth Upstream Edge Toward Screen Toward Bypass Downward 

(fraction of total) of Screen (ft) (ft/s) (ft/s) (ft/s) 

0.2 0.5 0.518 1.425 0.068 

0.2 2 0.586 1.295 0.087 

0.2 4 0.581 1.180 0.081 

0.2 6 0.612 1.277 0.062 

0.2 8 0.525 1.152 0.070 

0.2 10 0.517 1.013 0.060 

0.2 11.5 0.241 0.909 0.008 

0.5 0.5 0.634 1.371 0.208 

0.5 2 0.671 1.179 0.122 

0.5 4 0.625 1.099 0.083 

0.5 6 0.565 1.065 0.050 

0.5 8 0.543 0.937 0.066 

0.5 10 0.497 0.908 0.119 

0.5 11.5 0.281 0.922 0.168 

0.8 0.5 0.621 1.256 0.142 

0.8 2 0.673 1.116 0.100 

0.8 4 0.638 1.058 0.073 

0.8 6 0.608 0.988 0.069 

0.8 8 0.626 0.958 0.150 

0.8 10 0.553 0.881 0.136 

0.8 11.5 0.465 0.903 0.170 

0.9 0.5 0.800 1.028 0.167 

0.9 2 0.751 0.807 0.063 

0.9 4 0.767 0.909 0.051 

0.9 6 0.793 0.887 0.093 

0.9 8 0.686 0.675 0.114 

0.9 10 0.594 0.656 0.144 

0.9 11.5 0.571 0.714 0.174 
BAY 5, SCREEN 5, Bypass Flow Rate = 50 cfs 

Velocity data collected with a bypass flow rate of 50 cfs. 

Measurement Distance from Approach Velocity Sweep Velocity Vertical Velocity 

Depth Upstream Edge Toward Screen Toward Bypass Downward 

(fraction of total) of Screen (ft) (ft/s) (ft/s) (ft/s) 

0.2 0.5 0.994 1.748 -0.090 

0.2 2 0.886 1.530 -0.096 

0.2 4 0.813 1.435 -0.035 

0.2 6 0.729 1.391 -0.003 

0.2 8 0.662 1.304 0.011 

0.2 10 0.590 1.300 -0.005 

0.2 11.5 0.356 1.022 0.026 

0.5 0.5 0.951 1.515 0.381 

0.5 2 0.888 1.352 0.375 

0.5 4 0.793 1.094 0.390 

0.5 6 0.793 0.945 0.342 

0.5 8 0.717 0.967 0.007 

0.5 10 0.616 0.957 0.011 

0.5 11.5 0.317 1.171 0.071 

0.8 0.5 1.333 1.562 0.582 

0.8 2 1.283 1.252 0.642 

0.8 4 1.092 1.025 0.592 

0.8 6 0.931 0.891 0.372 

0.8 8 0.833 0.840 0.229 

0.8 10 0.676 0.764 0.010 

0.8 11.5 0.495 0.798 0.061 

0.9 0.5 1.383 1.576 0.471 

0.9 2 1.401 1.285 0.564 

0.9 4 1.187 1.029 0.501 

0.9 6 0.938 1.071 0.201 

0.9 8 0.837 0.838 0.163 

0.9 10 0.619 0.649 0.093 

0.9 11.5 0.456 0.605 0.057 
BAY 5, SCREEN 3, Bypass Flow Rate = 50 cfs 

Velocity data collected with a bypass flow rate of 50 cfs. 

Measurement Distance from Approach Velocity Sweep Velocity Vertical Velocity 

Depth Upstream Edge Toward Screen Toward Bypass Downward 

(fraction of total) of Screen (ft) (ft/s) (ft/s) (ft/s) 

0.2 0.5 0.584 1.308 -0.036 

0.2 2 0.525 1.060 -0.059 

0.2 4 0.555 1.030 -0.006 

0.2 6 0.583 1.015 -0.059 

0.2 8 0.563 0.925 -0.047 

0.2 10 0.529 0.826 -0.092 

0.2 11.5 0.345 0.755 -0.007 

0.5 0.5 0.624 0.980 -0.058 

0.5 2 0.627 0.895 -0.133 

0.5 4 0.606 0.842 -0.156 

0.5 6 0.646 0.890 -0.125 

0.5 8 0.631 0.919 -0.100 

0.5 10 0.597 0.906 -0.153 

0.5 11.5 0.396 0.939 -0.171 

0.8 0.5 0.842 0.844 -0.228 

0.8 2 0.732 0.751 -0.247 

0.8 4 0.789 0.770 -0.237 

0.8 6 0.870 0.881 -0.201 

0.8 8 0.816 0.786 -0.229 

0.8 10 0.742 0.821 -0.231 

0.8 11.5 0.621 0.939 -0.248 

0.9 0.5 0.810 0.831 -0.208 

0.9 2 0.829 0.851 -0.225 

0.9 4 0.921 0.912 -0.222 

0.9 6 0.862 0.884 -0.194 

0.9 8 0.765 0.876 -0.186 

0.9 10 0.746 0.953 -0.223 

0.9 11.5 0.617 0.933 -0.215 
BAY 5, SCREEN 2, Bypass Flow Rate = 50 cfs 

Velocity data collected with a bypass flow rate of 50 cfs. 

Measurement Distance from Approach Velocity Sweep Velocity Vertical Velocity 

Depth Upstream Edge Toward Screen Toward Bypass Downward 

(fraction of total) of Screen (ft) (ft/s) (ft/s) (ft/s) 

0.2 0.5 0.566 1.390 0.066 

0.2 2 0.676 1.279 0.052 

0.2 4 0.649 1.191 0.033 

0.2 6 0.589 1.093 0.025 

0.2 8 0.597 1.118 0.022 

0.2 10 0.507 1.006 0.013 

0.2 11.5 0.360 0.907 0.035 

0.5 0.5 0.662 1.257 0.060 

0.5 2 0.626 1.076 0.037 

0.5 4 0.633 1.079 0.015 

0.5 6 0.593 0.987 0.053 

0.5 8 0.525 0.919 0.025 

0.5 10 0.442 0.871 0.044 

0.5 11.5 0.257 0.920 0.117 

0.8 0.5 0.768 1.087 0.096 

0.8 2 0.757 0.980 0.111 

0.8 4 0.660 0.815 0.020 

0.8 6 0.665 0.852 0.077 

0.8 8 0.670 0.629 0.102 

0.8 10 0.446 0.472 0.052 

0.8 11.5 0.436 0.587 0.184 

0.9 0.5 0.754 1.077 0.150 

0.9 2 0.640 0.792 0.087 

0.9 4 0.578 0.706 -0.005 

0.9 6 0.563 0.573 0.016 

0.9 8 0.552 0.554 0.082 

0.9 10 0.521 0.510 0.118 

0.9 11.5 0.445 0.475 0.120 
APPENDIX II: Velocity Distributions in Front of Drum Screens 
-0.5

0

0.5

1

1.5

2

2.5

0 10 20 30 40 50 60 70 80

Location (ft)

Velocity (ft/s)

0.05 depth - V

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.05 depth - V

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - VsNOAA Screen Facility Design 

SCREEN 20 SCREEN 19 SCREEN 18 SCREEN 17 SCREEN 16

-0.5

0

0.5

1

1.5

2

2.5

0 10 20 30 40 50 60 70 80

Location (ft)

Velocity (ft/s)

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - VsNOAA Screen Facility Desig

SCREEN 20 SCREEN 19 SCREEN 18 SCREEN 17 SCREEN 16

Figure II-1. - Comparison of sweep (Vs) and approach (Va) velocity distributions on screens in Bay 2 at a fish bypass weir s

65 ft3/s (top) and 50 ft3/s (bottom). 
-0.5

0

0.5

1

1.5

2

2.5

0 10 20 30 40 50 60 70 80

Location (ft)

Velocity (ft/s)

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - VsNOAA Screen Facility Design 

SCREEN 5 SCREEN 4 SCREEN 3 SCREEN 2 SCREEN 1

-0.5

0

0.5

1

1.5

2

2.5

0 10 20 30 40 50 60 70 80

Location (ft)

Velocity (ft/s)

0.2 depth - Va

0.5 depth - Va

0.8 depth - Va

0.9 depth - Va

0.2 depth - Vs

0.5 depth - Vs

0.8 depth - Vs

0.9 depth - VsNOAA Screen CFacility Design C

SCREEN 5 SCREEN 4 SCREEN 3 SCREEN 2 SCREEN 1

Figure II-2. – Comparison of sweep (Vs) and approach (Va) velocity distributions on screens in Bay 5 at a fish bypass weir s

65 ft3/s (top) and 50 ft3/s (bottom).
0

0

0

.2

.3 0.3

0.4

0.4

0.5

0.5 0.5

0.6

0.6

0.6

0.7

0.7

0.8

0.8

0.8

0.9

1

1

1.1

0.2 0.3

0.4

0.5

0.6

0 2. 0.3

0.3

0.4

0.4

0.4

Location (ft)

Fraction of Depth from Water Surface (ft)

0 20 40 60 80

0

0.20.40.60.8

1

Va

1.21.110.90.80.70.60.50.40.30.20.10

PIER

PIER

PIER

Screen 20

Screen 19 Screen 18 Screen 17 Screen 16

PIER

0.6 0.8

1.2

1.2

1.4

1.4

1.6

1.6

1.8

0.8

1

1

1

0.8

1 1

1.2

Location (ft)

Fraction of Depth from Water Surface (ft)

0 20 40 60 80

0

0.20.40.60.8

1

Vs

21.81.61.41.210.80.60.40.2

PIER

PIER

PIER

Screen 20 Screen 19

Screen 18 Screen 17 Screen 16

PIER

Figure II-3. –Appro

ach (Va, top) and sweep (Vs, bottom) velocity distributions in Bay 2 at a primary bypass flow rate of 6

5 ft

Black d

ots represent measurement locations at fra

ctional water depths of 0.05, 0.2, 0.5, 0.8, and 0.9. 
0

.

4

0

.

5

0

6

.

0

.

6

0

.7

0

.7

0

.8

0

.

8

0

.9

0

.91

1

.1

0

.

4

0.

5

0

.

5

0.

6

0.6

0.7

0

.

3

0

.

4

0

.

5

0.

6

0

.

6

0

.6

0

.7

Location (ft)

Fraction ofDepthfromWaterSurface(ft)

0 20 40 60 80

0

0.20.40.60.8

1

Va

1.21.110.90.80.70.60.50.40.30.20.10

PIER

PIER

PIER

Screen 5 Screen 4 Screen 3 Screen 2 Screen 1

PIER

0

.

8

0

.8

1

1

1.2

1.2

1

.4

1.

6

1

.

6

1

1

1

1

.

2

Location (ft)

Fraction ofDepthfromWaterSurface(ft)

0 20 40 60 80

0

0.20.40.60.8

1

Vs

21.81.61.41.210.80.60.40.2

PIER

PIER

PIER

Screen 5 Screen 4 Screen 3 Screen 2 Screen 1

PIER

Figure II-4. –Approach (Va, top) and sweep (Vs, bottom) velocity distributions in Bay 5 at a primary bypass flow rate of 65 ftBlack dots represent measurement locations at fractional water depths of 0.2, 0.5, 0.8, and 0.9. 
0

.

4

0

.5

0.5

0

.6

0

.7

0

.

7

0

.8

0

.8

0

.9

1

1

1

.1

1.2

0

.4

0

.

4

0

.5

0.5

0

.

5

0

.

5

0

.

6

0

.0 6

.7

0

.

4

0

.5

0

.

5 0.6

0.7

Location (ft)

FractionofDepthfromWaterSurface(ft)

0 20 40 60 80

0

0.20.40.60.8

1

Va

1.21.110.90.80.70.60.50.40.30.20.10

PIER

PIER

PIER

Screen 20 Screen 19 Screen 18 Screen 17 Screen 16

PIER

0.8

1

1

1.

2

1

.

2

1

.4

1.6

1

.8

0

.

8

0

.

8

0

.8

0.

8

1

Location (ft)

FractionofDepthfromWaterSurface(ft)

0 20 40 60 80

0

0.20.40.60.8

1

Vs

21.81.61.41.210.80.60.40.2

PIER

PIER

PIER

Screen 20 Screen 19 Screen 18 Screen 17 Screen 16

PIER

Figure II-5. –Approach (Va, top) and sweep (Vs, bottom) velocity distributions in Bay 2 at a primary bypass flow rate of 50 ftBlack dots represent measurement locations at fractional water depths of 0.2, 0.5, 0.8, and 0.9.
0

.

8

1

1

1

.

2

1

.

2

1

.

4

1

.

4

1

.

6

0

.8

0

.8

0

.

8

1

1

.

2

0.8

0.

8

1

1

1

.

2

Location (ft)

Fraction ofDepthfromWaterSurface(ft)

0 20 40 60 80

0

0.20.40.60.8

1

Vs

21.81.61.41.210.80.60.40.2

PIER

PIER

PIER

Screen 5 Screen 4 Screen 3 Screen 2 Screen 1

PIER

0

.

4

0

.

5

0

.

6

0

.

6

0

.7

0

.

7

0

.8

0

.

8

0

.

9

0

.9 1

1

.1

0

.

4

0

.

5

0

.6

0

.6

0.7

0

.

70

.

8

0

.

9

0

.

4

0.4

0

.

5

0

.

5

0

.6

0

.

7

Location (ft)

Fraction ofDepthfromWaterSurface(ft)

0 20 40 60 80

0

0.20.40.60.8

1

Va

1.21.110.90.80.70.60.50.40.30.20.10

PIER

PIER

PIER

Screen 5 Screen 4 Screen 3 Screen 2 Screen 1

PIER

Figure II-6. –Approach (Va, top) and sweep (Vs, bottom) velocity distributions in Bay 5 at a primary bypass flow rate of 50 ftBlack dots represent measurement locations at fractional water depths of 0.2, 0.5, 0.8, and 0.9.