7187

• UCREFRP Catalog Number: 7187
• Author: Mustard, E. W. and C. D. Rector.
• Title: Wetlands, Irrigation and Salinity Control
• USFW Year: 1979.
• USFW - Doc Type: Lower Gunnison River Basin, Colorado.
• Copyright Material: YES

farm water management practices (open drains,
tile drains, intercept drains, lined ditches,
irrigation efficiency, etc.). Seepage from a
canal or ditch constructed on a hillside fre-
quently supported wetlands on the slope and
valley below. Seepage from recessed water
conveyance systems rarely supported wetland
growth beyond the ditchbank.
Mean habitat values for wetlands sup-
ported by various water sources are given in
Table 1. Natural wetlands and those sup-
ported in part by natural water sources
consistently rated higher in habitat value
than wetlands depending on canal water, on-
farm irrigation water or combinations of
these.
Phase II - Intensive Assessment
Biological inventories of the 30 sample
wetlands indicated a high species diversity.
A total of 123 bird species, 18 species of
mammals and various reptiles and amphibians
were observed. More than 80 plant species
associated with wetlands were identified.
Species observed are given in Rector et al.
(1979). Wildlife use ratings ranged from 4
to 32 and averaged 18 on a scale of 0 to 50
(Table 2).
A direct correlation between habitat
value ratings and wildlife use ratings was
observed, with an overall correlation coeffi-
cient for individual sites of r = 0.6. Com-
parison of site means for these ratings by
water source, wetland class and location
resulted in correlation coefficients of r =
0.9 or greater.
When wetlands were compared by water
source (fig. 2),' natural wetlands had the
highest wildlife use rating, followed by
canal and on-farm irrigation wetlands.
Comparison of the major FWS wetland types
indicated emergent/interspersed with water
wetlands were most valuable, followed by
forest, scrub/ shrub and emergent/narrow-
leaved (fig. 3). Wetlands located on river-
bottoms rated higher than those east or west
of the bottomlands (fig. 4).
Table 1. -Wetland inventory summary, Lower Gunnison River Basin. Colorado. 1977
-
Wetlands
No. Total
Hectares Mean
Size (ha) Pct. of Total
Wetland Area Mean Habitati
Value Rating
BY WATER SOURCE
Natural 207 5269 25.5 60.1 89
Irrigation Management 191 1342 7.0 15.3 70
Canal 92 153 1.7 1.7 71
Natural b Irrigation Management 203 1683 8.3 19.2 75
Natural 6 Canal 50 72 1.4 0.8 78
Natural b Irrigation Mgmt. b Canal 13 9 0.6 0.1 80
Irrigation Management b Canal 44 245 5.6 2.8 74
Total 800 8773 11.0 100.0 78
BY LOCATION2
On-Farm 594 5405 9.1 61.6 76
South Canal 8 97 12.1 1.1 74
West Canal 22 24 1.1 0.3 76.
Montrose 6 Delta Canal 60 35 0.6 0.4 79
Loutzenhlzer Canal 10 5 0.5 0.1 71
Selig Canal 27 31 1.1 0.4 66
Ironstone Canal 24 35 1.5 0.4 77
East Canal 16 15 0.9 0.2 67
' Carnet Canal 8 6 0.7 0.1 71
Gunnison River 9 1053 117.0 12.0 107
Uncompahgre River 22 1067 94.0 23.6 110
Total On-Farm 594 5405 9.1 61.6 76
" Total Canal 175 248 1.4 2.8 73
Total River 31 3120 100.6 35.6 108
BY DOMINANT CLASS/SUBCLASS
Forested - Broad-leaved deciduous 124 3478 28.0 39.6 93
. Emergent - Narrow-leaved 300 2402 8.0 27.4 72
Shrub - Broad-leaved'deciduous 165 962 5.8 8.6 80
Emergent - Interspersed with water 56 318 5.7 3.6 80
_ Flat - Vegetated 29 100 3.4 1.1 66
'Wildlife habitat value rating can range from 41-123: a wetland may receive 5 additional points for out-
standing wildlife populations.
'.2A total of 270 wetlands were locat ed "On-Farm " with 45% of the study area sampled. Number and area of on-
farmyetlands were multiplied by a facto r of 2.2 to estimate total on-Farm wetlands based on extrapolation
of sample data. All others are based on 100% sampl es. .
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