During the smolt transportation season, fish collected from the juvenile bypass systems at Lower Granite, Little Goose, Lower Monumental, and McNary dams are either trucked or barged to an in-river release point below Bonneville Dam. PTAGIS maintains PIT tag interrogation equipment in these facilities with site codes of GRJ, GOJ, LMJ, and MCJ, respectively. The following information is pertinent only to these four sites. All fish passing through juvenile bypass systems at other hydroelectric facilities are returned to the river by default.
At the four transportation facilities, the juvenile fish pass through a size and/or debris separator and are then routed into the collection facility. Adult salmon “fallbacks” are diverted from the separator and returned to the dam’s tailrace. During transportation season, fish are generally routed into the collection facility’s raceways where they are held until loaded onto a barge or tanker truck. Under some circumstances, the fish are direct-loaded to a barge as soon as they pass over the separator. A sample portion of the fish exiting the separator are routed to the facility’s lab, where biologists determine the species composition and densities of the group(s) of fish to be transported. Sample fish are also transported.
Beginning in 1993, PIT-tagged fish exiting the separator at these four sites have been bypassed directly back to the river by default. In 1996 this capability was expanded to allow the automatic segregation of specific PIT-tagged fish. This selective segregation of PIT-tagged fish is called Separation by Code (SbyC). Separation by Code can be used to override the default bypassing of fish back to the river, or to collect a target group of fish for further hands-on sampling.
PTAGIS maintains PIT tag detectors in all of the routes through the smolt collection facilities, providing the means to track the movement of each fish through the facility. With this information it is possible to determine which PIT-tagged fish have been bypassed back to the river with high confidence, and to infer (but not confirm) which fish have been transported.
Using Last Antenna Group to Infer Disposition
The Interrogation Summary report, available through Query Builder 2 in the Advanced Reporting system, returns a single record for each PIT tag code detected at a detection site. It also provides the time stamp and antenna group name of the tag’s first and last detection at the site. The Last Antenna Group attribute can be used to determine which PIT-tagged fish were bypassed back to the tailrace and to infer which fish were transported from the facility (see Caveats).
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Last Antenna Group Name
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Detection Time
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Disposition
|
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FULL FLOW BYPASS
ADULT FISH RETURN
DIVERSION RIVER EXIT
SBYC RIVER EXIT
RIVER-1 EXIT
RIVER-2EXIT
BYPASS RIVER EXIT
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Any
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Bypassed
|
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If the name contains:
RACEWAY
or
SAMPLE
or
SUBSAMPLE
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During transportation season
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Probably Transported
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If the name contains:
RACEWAY
and
EXIT
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Outside of transportation season
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Probably Bypassed
|
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DIVERSION GATE
SBYC GATE
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Any
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Not Transported
but may not have been returned to the river
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At LMJ:
A-EXIT
B-EXIT
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During transportation season
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Transported (direct-loaded)
Or
Bypassed
-contact Corps’ site biologist for more information about these operations
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Any other name
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Any
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Unknown – last detected at some intermediate point in the facility
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Caveats
- The transportation season at a site may be shorter than the collection season. Fish may be collected (passed through the separator) for monitoring purposes prior to the start of the transportation season. PTAGIS has attempted to record the dates when collection for transportation started and ended each year in each site’s Event Log, but these dates should be confirmed by Corps personnel.
- McNary Dam had a “Spread the Risk” policy implemented for a number of years that called for the bypass of most fish during the spring, and transportation of most fish during Summer-like conditions. During the spring, only PIT-tagged fish marked for the Corps of Engineer’s Smolt Transportation Evaluation study were targeted for transportation; all other PIT-tagged fish were routed back to the tailrace and bypassed. In recent years, McNary has not had a transportation season. Contact the site biologist for more information about these operations.
- During the transportation season, not all fish at a “Raceway” antenna group are transported. On occasion, raceways are intentionally emptied to the river. If the fish in these raceways are routed through a pipe without a PIT tag monitor, or pass through a monitored pipe at a high density, they may exit the facility without a last “River” detection.
- If a gate below a “Raceway” monitor leaks or fails, then fish may be routed out to the barge loading dock and dropped into the river, rather than loaded onto a barge and transported.
PTAGIS recommends that you contact the Corps’ site biologist to confirm transportation season dates and to inquire about any possible operational anomalies that may have occurred during the years in which you are interested.