9371

• UCREFRP Catalog Number: 9371
• Author: Levee Removal Evaluation Group.
• Title: Green River levee Removal and Floodplain Connectivity Evaluation.
• USFW Year: 1998.
• USFW - Doc Type: CAP-6 LR,
• Copyright Material: NO

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The Stirrup
This site is located at RM 276 on river left. It was sampled in 1997 and 1998 after a 480'
long, 20' wide, 2.5' deep channel was cut in March 1997. This channel was cut into a natural
swale which allows for a hydraulic connection to the main portion of the wetland. It takes several
weeks for the 19.2 acre (34 acres when full) Stirrup site to backfill after flooding discharges are
reached due to the long narrow configuration of this channel. On June 19-21, 1998, when most
of the other sites made significant re-connection, the Stirrup wetland did not have sufficient
inflow to turn a flow meter. The long narrow configuration of the breach created a very shallow
and debris filled channel, thereby inhibiting larval fish drift into the site. Sedimentation and
vegetation blocking the connection caused this wetland to require about 13,700 cfs to begin
filling in 1998. The outer edges of the wetland are dominated by tamarisk with areas of open
water in the center. This site is correctly classified as a depression. Water levels were still
nearly 2.0 meters deep in October of 1998, indicating fish will likely overwinter. Because of this
it was selected for an experimental stocking of 1997 year class razorback suckers.
Baeser Bend
This site is located on river left at RM 273. It was only sampled in 1998 after a 200' long,
20' wide channel was cut into the levee in October 1997. This site inundates 38.2 acres at 13,000
cfs (60 acres when full). Unlike most of the other sites, the breach in this levee was made near
the middle of the wetland instead of at the downstream end. This allowed for a more rapid filling
of the site, with current flowing into the breach instead of backfilling into the site. Down cutting
of a narrow channel took place as the site filled, causing a small delta to form inside the wetland.
Vegetation in the site consists of tamarisk around the edges with large areas of thick cattails and
dead hardstem bulrush. This site is correctly classified as a depression and is likely to overwinter
fish.
Above Brennan
This floodplain wetland is located on river left at RM 268.5, and was sampled during all
three years of study. A 100' long channel 40' wide at the mouth and narrowing to 20' wide was
cut in October 1997 to match the existing outlet drain. At 13,000 cfs, 40.7 acres (63 acres when
full) are flooded making it the largest of the floodplain wetlands located on BLM lands.
Vegetation consists of tamarisk and reeds, with extensive fallen plant debris. When full, depths
exceed 5 meters in some places creating larger areas of open water than at the other sites. Above
Brennan has two connection points: the artificially lowered levee on the downstream end where
backfilling occurs; and, a natural 10' wide inlet on the upper end which floods through thick
vegetation at 12,900 cfs. The two inlet connections allow the Above Brennan wetland to fill
rapidly despite its large size. Above Brennan is correctly classified as a depression and has
overwintered fish during each year of the study.
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