9641

• UCREFRP Catalog Number: 9641
• Author: Hedrick, T. N., K. R. Bestgen and K. D. Christopherson.
• Title: Entrainment of Semi-Buoyant Beads and Razorback Sucker, Xyrauchen texanus, Larvae into Flood Plain Wetlands of the Middle Green River, Utah.
• USFW Year: 2009.
• USFW - Doc Type: C-6/RZ-ENTR,
• Copyright Material: NO

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velocities as well (unpublished data, KRB). Current velocity is increased in the immediate

vicinity of the outflow, but those areas are small and are unlikely to harbor an important

percentage of entrained larvae. Even if small numbers of larvae are transported through the

wetland, flow-through wetlands still offer the greatest opportunity for entrainment, retention, and

survival of razorback sucker larvae under the flow conditions we tested.

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2006

Building on findings in 2005 that suggested flow-through wetlands had higher

entrainment rates compared to single breach wetlands, we focused on estimating entrainment

. rates of beads and water in flow-through wetlands in 2006.

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Thunder Ranch, 2006
In 2006, Thunder Ranch connected at about 402.1 m3/sec, a connection level consistent
with observations in 2005. Sampling began on 21 May when flows at the Jensen gauge read
420.0 m3/sec.

Four sampling occasions were conducted at Thunder Ranch in 2006, three on the

ascending limb of the hydrograph, and one on the descending limb. Both Breach 3 and 5 were

sampled in 2006 (versus only Breach 3 in 2005) to obtain better estimates of entrainment;

breaches 3 and 5 were the only inlets to this wetland sampled in 2006. Flow and bead

entrainment increased as river stage increased (Tables 9 and 10, Figure 16), and the correlation

between percent flow and bead entrainment was high (0.98). Percent flow and bead entrainment

also increased as river stage increased. For example as river flow increased 45-50 m3/sec

between the first and second, and second and third releases, the percent of flow entrained

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