9504

• UCREFRP Catalog Number: 9504
• Author: Cooper, D. J. and C. Severn.
• Title: Ecological Characteristics of Wetlands at the Wetland Clough, Moab, Utah.
• USFW Year: 1994.
• USFW - Doc Type: \
• Copyright Material: NO

years in the La Sal Mountains. Thus,. good late summer and-even
winter flows-could have occurred in Mill.Creek and-its ground
water flow system which would have kept wetland water levels-high
into and most likely through the winter.- We hypothesize that the
ample beaver populations of these wetlands. would also have
occupied Mill Creek prior to that creeks channelization. Their
dams could have impounded the river in the vicinity of the-
:-current wetlands and provided higher water tables and hydrologic.
support-than occurs today.. Thus, overwinter fish survival could
,have been high.
If Figure 7 is reviewed-it can be seen that high flow-years
typically occur in sequence,-representing wet periods which may
- be E1 Nino's. Adult, juvenile, and larval fishes trapped in the
wetlands one year, would-have an excellent-opportunity for
movement to the river during the subsequent high water-event.
(2) Reduced salt flushincr. The large salt plume extending
-from east to west across: he northern portion of the site is ,one
of the most characteristic-aspects of the .study area. It is as
prominent as the large-wetland complexes. in the southern portion-
of the study area, but less visible ,until the chemical analysis
revealed-the pattern. .The vegetation of this portion of the
study can now be understood. We hypothesize that reduced
flooding frequency has allowed salts to accumulate over the past
t'~ 3 decades producing-an extremely concentrated pool of briny
ground water.
This .brine will limit the vegetation,-:composition of the
northern study area to halophytes, such as salt grass (Distichlis
spicata) and salt cedar (Tamarix ramossissima). -The boundaries
of this brine pool are determined on the west and north by the
Colorado River and on the south by ground water flow from the
wetland complexes supported-there. It is imperative .that a
positive gradient ,from south to north and east to west in the
southern portion of the study area be maintained to keep-the
brine pool from expanding. to the south.
Maintaining healthy and .active beaver .populations is
important-for maintaining a high water table and positive head.
from south to north and south to west in the southern area.
Beaver control should not-be attempted until a clear idea of
beaver .populations and the carrying capacity of the southern
areas willow and cottonwood tree populations- are for beavers . If
the woody plant population is sufficient to support large beaver
..populations then the.beavers:should be left alone.
(3) Reduced alluvial-sediment deposition. Reduced flooding
has reduced sediment-input to the wetlands and other portions of
the study area. Colorado River sediment could provide an
74