HomeMy WebLinkAbout1.02 Wildlife and Habitat Assessment
WILDLIFE AND HABITAT ASSESSMENT
NORTH HANG’S RANCH PARCEL
GARFIELD COUNTY, COLORADO
PREPARED FOR:
Western Slope Materials LLC
Sean Mello, General Manager
PO Box 1319
Carbondale, CO 81623
Prepared by:
Environmental Solutions, Inc.
Steve D. Dahmer, Principal Ecologist
600 CR 216
Rifle, CO 81650
April 2021
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TABLE OF CONTENTS
1.0 Introduction ………………………………………………………………….. 3
2.0 Proposed Action ……………………………………………………………... 3
3.0 Methods ……………………………………………………………………… 3
4.0 Study Area Description ……………………………………………………… 4
5.0 Significant Wildlife Use of the Property …………………………………….. 5
6.0 Potential Effects of the Proposed Project ……………………………………. 7
7.0 Literature Cited ………………………………………………………………. 10
8.0 Photographic Documentation of Existing Conditions ……………………….. 13
LIST OF FIGURES
1 - General Location Map ……………………………………………………….. 15
LIST OF TABLES
Table 1: Common plants found on the North Hang’s Ranch study area …..………… 11
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1.0 Introduction
This report presents an evaluation of existing wildlife use and wildlife habitat conditions
on the North Hang’s Ranch parcel (the “Property”) located approximately ½ mile
southwest of Silt, Colorado along the Colorado River. The 72.8-acre parcel is located in
Section 9, Township 6 South, Range 92 West, in unincorporated Garfield County (Figure
1). The following analysis addresses significant wildlife uses currently occurring on the
Property, and evaluates the condition and functional values of the various habitat types
found on the site. The report further addresses potential short- and long-term effects of
the proposed action on the identified wildlife resources, including specific evaluations for
species of concern.
2.0 Proposed Action
The project sponsor has proposed a surface extraction operation to mine sand and gravel
resources on the Property. Operations would be conducted in phases, with portions of the
Property being extracted sequentially. The actual timeline will vary depending on market
demand for the gravel resources, but it is currently anticipated that all mining would be
completed within a 10-year period, with operations commencing no sooner than 2026.
It is anticipated that a number of mitigation measures would be implemented to create a
variety of wildlife habitats upon completion of mining, and a detailed mitigation plan will
be prepared as part of the permit approval process.
3.0 Methods
The wildlife assessment presented herein was based on the following:
a) A review of the Colorado Natural Heritage Program (CNHP) database for
Garfield County.
b) A review of the NatureServe Explorer database for Garfield County
c) A review of current Colorado Parks and Wildlife (CPW) Natural Diversity
Information Source (NDIS) species distribution maps.
d) A review of Natural Resource Conservation Service (NRCS) soils data.
e) Field surveys of the Property.
f) The author’s extensive field experience with a variety of wildlife and habitat-
related matters in this region.
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4.0 Study Area Description
Site Description
The project area consists of approximately 72.8 acres of lowland-riparian habitats and
agricultural lands along the Colorado River corridor. A significant portion of the
Property is flood-irrigated, and there is one major irrigation ditch system (Bernudy Ditch)
serving other properties which flows through the parcel from east to west. The Property
has historically been used as a ranch, both for grazing and hay production. There are a
number of fences, 2-track access roads, extensive irrigation lateral ditches, old culverts
and other farming implements and debris scattered throughout the parcel. Much of the
property falls within the historical floodplain of the Colorado River and contains remnant
cottonwood galleries and evidence of some old floodplain channels, mainly on the
northern half of the parcel, though none currently show any evidence of recent
inundation.
Vegetation
The Property contains a significant area of planted hayfields and pastures, mainly
consisting of Orchardgrass (Dactylis glomerata), Smooth brome (Bromus inermis),
redtop bentgrass (Agrostis stolonifera), Kentucky bluegrass (Poa pratensis), red fescue
(Festuca rubra) and some alfalfa (Medicago sativa). Flood irrigation activities have also
promoted hydrophytes to establish in the more low-lying areas, and these include Arctic
rush (Juncus arcticus), Clustered field sedge (Carex praegracilis), tall scouring rush
(Equisetum hyemale), inland saltgrass (Distichlis spicata) and beaked sedge (Carex
utriculata).
Upland areas consist of two distinct vegetation communities: mature cottonwood
galleries or sagebrush/rabbitbrush shrublands. The cottonwood galleries generally occur
along the riparian corridor near the river and along the old floodplain channels. These are
dominated by an overstory of mature narrowleaf cottonwood (Populus angustifolia) and
Fremont cottonwood (Populus fremontii) with a dense mid-story of invasive Russian
olive (Elaeagnus angustifolia) and Siberian elm (Ulmus pumila). Many of the
cottonwoods are dead-standing and the remainder are very mature, old trees nearing the
end of their life cycle. The herbaceous understory is generally sparse consisting of
intermediate wheatgrass (Thinopyrum intermedium), smooth brome (Bromus inermis),
orchardgrass (Dactylis glomerata), globemallow (Sphaeralcea coccinea) and weedy
forbs such as musk thistle (Carduus nutans), houndstongue (Cynoglossum officinale) and
curlycup gumweed (Grindelia squarossa).
The drier uplands are dominated by big sagebrush (Artemisia tridentata), rabbitbrush
(Chrysothamnus nauseosus) and some Greasewood (Sarcobatus vermiculatus) with an
understory of Basin wildrye (Elymus cinereus), Western wheatgrass (Agropyron smithii),
Quackgrass (Elymus repens) and a variety of weedy species, including Kochia (Kochia
scoparia), Russian knapweed (Acroptilon repens), Scotch thistle (Onopordum
acanthium), cheatgrass (Bromus tectorum), Horseweed (Conyza canadensis) and Prickly
lettuce (Lactuca serriola). The upland sites have an extensive infestation of Russian
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olive trees (Elaeagnus angustifolia), which are on the State noxious weed list and which
are rampant throughout the lower Colorado River valley. This species of scrubby tree
provides little wildlife value, and is a strong competitor with all of the native tree and
shrub species in the valley.
Wetland areas on the Property contain mainly grass-grasslike and forb vegetation, though
some areas of scrub/shrub wetland areas are present, particularly adjacent to the river. A
significant amount of the identified wetland areas are agriculturally-induced due to flood
irrigation and seepage from the main lateral ditches on the Property. The dominant
vegetation of the wetland areas consists of Arctic rush (Juncus arcticus), small-wing
sedge (Carex microptera), clustered field sedge (Carex praegracilis), inland saltgrass
(Distichlis spicata) and tall scouring rush (Equisetum hyemale). Some of the lowest
ditches have stands of reed canarygrass (Phalaris arundinacea), broadleaf cattail (Typha
lattifolia), hardstem bulrush (Schoenoplectus acutis), water sedge (Carex aquatilis) and
creeping spikerush (Eleocharis palustris).
There is a small contingent of Hawthorn (Crataegus erythropoda), Coyote willow (Salix
exigua), Wood’s rose (Rosa woodsii) and Skunkbush sumac (Rhus trilobata) also
scattered through the property, though the Russian olives are rapidly excluding these
more desirable species. A list of plant species encountered on the property is provided in
Table 1.
Soils
Soils encountered on the site were comprised of Wann sandy loams 1-3% slopes,
Halaquepts, nearly level, and Torrifluvents, nearly level, as mapped by the NRCS. All of
these soils are alkali-affected to varying degrees, which, combined with flood-irrigation
practices, accounts for the patches of Inland saltgrass, greasewood and other species
adapted to such conditions.
The soils ranged from fine silty loams to cobbly-sandy loams, which varied from well-
drained to somewhat-poorly drained, depending on location. Most areas have a very
shallow overburden of soils and extensive alluvial deposits of mixed aggregate material,
which makes this site extremely attractive for sand and gravel extraction.
5.0 Significant Wildlife Use of the Property
Records searches and the site visits revealed a number of wildlife species known to use
the Property. Despite the generally degraded condition of most of the upland areas, a
diverse array of species frequent the Property, including coyote, red fox, cottontail rabbit,
and other small mammals. A diverse variety of bird species utilize the area, at least
seasonally, including a wide range of songbirds, waterfowl and raptor species. Further,
several amphibian species and reptiles can be found on the Property, and the wet areas
host a tremendous variety of insects, which are the basis of the food chain for many of the
species listed above.
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Time and space constraints dictate that this analysis will focus on those wildlife species
that are of significant ecological, economic, regulatory or political importance. Other
species or ecological elements assuredly occur on the Property, but are omitted in this
discussion due to one or more of the following: 1) they will not be significantly impacted
by the proposed action; 2) they are not specifically regulated by local, state or federal law
or code; 3) their life cycle and/or habitat use criterion do not make them reasonable
indicators of probable effects to other wildlife species.
Four species were selected for analysis because of their regulatory status, sensitivity to
human activities, known use of the study area, limited habitat resources in the region
and/or their ability to serve as indicators of probable effects to a variety of other wildlife
species. Each species is discussed, complete with known-use history, special habitat
availability and likelihood of continued future habitat capability for the species.
Mule Deer: These are large ungulate browsers, important to social and economic
functions of local communities. Further, this species serves as an “umbrella species,”
which means that if habitat requirements to meet the needs of this species are present,
then we can safely assume that a great many other species will be adequately supported
in the area as well (Caro & O’Doherty 1999, Lambeck 1997, Roberge & Angelstam
2004).
Mule deer are known to utilize the site sporadically throughout the year. The Property is
not considered to be a production area or normal summer range for the species and there
are no migration corridors mapped on the site by CPW. The entire Property is mapped as
mule deer winter range, and the southern half of the parcel is noted as a Winter
Concentration Area, which areas are defined as locations that harbor 200% higher
densities of animals than surrounding areas of defined winter range in the five average
winters out of ten. However, because of the lack of native shrub species and the bulk of
the site consisting of irrigated grass pastures or grassy wetland vegetation, there is
relatively little forage available for deer, particularly under the severe, deep-snow
circumstances which would force them to utilize the area. Site visits from April through
December of 2020 did note the presence of 3-5 mule deer on a somewhat regular basis,
usually in the far northwestern corner of the Property where a sagebrush/rabbitbrush
community is the dominant vegetation. The largest group sighted contained two adult
does with a yearling and two fawns. No bucks were ever documented. Tracks and scat
were noted sporadically in other locations around the Property.
Bald Eagle: There are no Bald eagle nests nor roost sites known to occur on the Property,
though there is an active nest site approximately 0.8 miles southeast of the Property, and
another approximately 4 miles to the west. There are mature cottonwoods suitable for
eagle nest sites on the parcel and it would appear to be an attractive location for nesting.
These trees would also provide perches for hunting or roosting along the river. However,
bald eagles are territorial and the presence of other nearby active nest sites likely
precludes adoption of this location for a nest site at present. Abundant, mature stands of
cottonwoods and Ponderosa pine exist both upstream and downstream of the Property,
and provide a plethora of habitat for this species. The entirety of the Colorado River
corridor is mapped by CPW as summer and winter foraging habitat for bald eagles.
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The river is the critical component to eagle use of the Property, as it provides the only
water available to support a Bald eagle’s chief sources of food: fish and waterfowl. A
significant migratory population of Bald eagles winter along the Colorado River,
generally arriving in late fall and remaining along the river corridor until early spring. A
winter concentration area is mapped by CPW approximately 2.9 miles east of the
Property. There are a number of regular winter roost sites well-known along the river
corridor from Battlement Mesa all the way to Dotsero, though any mature tree with large,
clear branches near the river may be used intermittently.
Great Blue Heron: Great blue herons are included because they select relatively quiet,
undisturbed riparian sites to set up nesting colonies, and they require healthy aquatic
ecosystems to provide adequate food resources. As such, they are an excellent indicator
of the relative health and viability of many other species in the area.
There is a known, active nesting colony (rookery) located approximately 0.7 miles
upstream of the Property, and another nesting area mapped approximately 2 miles
downstream. There are no active nest sites on the Property itself. There are some suitable
floodplain habitats along the river and the flood-irrigated pasture areas as well as the
Bernudy Ditch itself provide foraging habitat and food sources for herons. No herons
were observed on the Property during any of the site visits, though the existing foraging
habitat and reasonable proximity to an existing rookery would indicate that it likely
receives some use by this species at present. CPW has mapped the northern half of the
Property as foraging habitat.
Sandhill Crane: Sandhill cranes are not known to nest in the area, and CPW has no
mapped habitat designations for them in the area. They do, however, occasionally stop
over along the Colorado River during spring and fall migration. This use is intermittent,
at best, and seldom involves more than a handful of birds. Sandhill cranes prefer broad,
open habitats that allow them to see predators at a distance and avoid ambush. They
therefore frequent large rivers on sandbars, large, open lakeshores or islands and also
large, unobstructed agricultural grain fields. Since most agricultural production in the
lower Colorado River valley involves grass and alfalfa production and relatively little
grain production, the agricultural fields are not heavily targeted by migrating birds.
Rather, the cranes generally search for open islands and sandbars in braided sections of
the Colorado River where they can feed on amphibians and crustaceans and rest in
relative safety. Some of the floodplain areas with grassy wetlands on the Property could
provide stopover habitat for migrating cranes, though the proximity of willow stands and
the encroachment of the Russian olive trees has significantly reduced visibility and make
cranes vulnerable to ground-based predators such as coyotes. There are no documented
reports of cranes using the Property.
6.0 Potential Effects of the Proposed Project
The proposed project will result in removal of a significant amount of rock and gravel
resources below the existing grade, which will result in the creation of one large lake on
the Property. As part of the mitigation measures, pond depth, shoreline slopes and layout
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as well as submerged slopes will all be designed to establish a variety of habitat types to
meet requirements of a diverse array of wildlife species. This will include creation of
fisheries, including deepwater habitats, as well as perennial wetland vegetation
communities, both emergent and wet-meadow types. It is anticipated that mitigation will
include planting of a broad selection of wetland and upland species to maximize the
productivity and diversity of habitats on the Property. A comprehensive mitigation plan
will be developed as part of the permitting process.
Creation of the lake will result in increased diversity by adding deep water habitat,
fisheries which currently do not exist, and a great deal of “edge”, which is how biologists
define the convergence of two or more habitat types. Edges tend to be very attractive to a
great many wildlife species, providing food and cover in close proximity. As a result,
habitat edges support an enormous diversity of wildlife species, which will increase the
value of the Property as a wildlife area and provide a number of recreational
opportunities for people.
Finally, there will be a 100-foot buffer along the river itself, which will protect many of
the existing cottonwoods on the site as well as the riparian-wetlands along the river bank.
Potential effects and opportunities posed by the project for the key species identified in
Section 5 are discussed below.
Mule Deer: Since mule deer make little use of the Property, the gravel pit operations are
unlikely to have any detrimental effects to this species, nor will creation of the lake be
likely to enhance habitat for them. Mitigation measures that increase the shrub and tree
component of the vegetative community and create additional cover and feed resources
(which would be available above snowpack in severe winters) would be of great benefit
to mule deer, and removal of the invasive Russian olive trees would also be beneficial.
Bald Eagle: The loss of tall snags and mature tree species on the Property would
negatively affect the site’s suitability for nesting and roosting. However, many of the
existing mature trees fall within the 100-foot buffer strip along the river and will remain
intact. Available habitat for key prey species on which eagles depend is currently limited
on the Property. The mining operation has the potential to create a great deal of habitat
for prey species, particularly for fish and waterfowl, which would provide an increased
prey base for eagles. Further, mitigation measures such as tree planting or establishment
of artificial nest structures could also improve suitability of the Property for Bald eagles.
Such measures could provide a significant benefit relatively quickly, especially for the
migratory population of Bald eagles that winter along the Colorado River.
Great Blue Heron: A healthy population of Great blue herons are present throughout the
valley though no nesting colonies occur on the Property. The loss of mature trees would
decrease the potential for nesting colonies to establish on the Property, though many of
the existing mature trees will remain within the 100-foot buffer along the river. The
grassy flood-irrigated fields, low swales, the Bernudy Ditch itself and river shoreline do
provide some adequate foraging habitat for the birds.
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Creating fisheries in the ponds after mining has been completed could provide an
excellent source of food for the herons, and the creation of emergent wetlands on the
pond fringes will add diversity and a significant food base as well. Planting of
cottonwoods on the reclaimed site will eventually create suitable habitat for a rookery.
Sandhill Crane: Sandhill crane use along the Colorado River is sporadic during spring
and fall migration, and generally involves small flocks or pairs of birds when it occurs.
There is no documented use of the Property by this species, and suitable habitat is
currently limited due to the encroachment of Russian olive trees which decrease sight
distance and make the birds vulnerable to predation. The creation of lakes on the site
opens an opportunity to create island features, which would provide roosting security for
this species. The lake and wetland fringe creation would also enhance the food base as
described for Great Blue herons, making the site attractive as a stopover for migrating
cranes. However, since current crane use of the entire lower Colorado River valley is so
sporadic currently, it would not be prudent to expect a single 72-acre site to create
enough of an attraction to increase crane stopover to any appreciable degree.
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7.0 Literature Cited
Andrews, Robert and Righter, Robert. 1992. Colorado Birds. Denver Museum of
Natural History. Denver, CO.
Caro, T.M., and G. O’Doherty. 1999. On the Use of Surrogate Species in Conservation
Biology. 13:805.
Colorado Parks and Wildlife. 2021. Natural Diversity Information Source. Colorado
Species Distribution Maps. Available https://ndismaps.nrel.colostate.edu
Accessed: April 9, 2021).
Colorado Natural Heritage Program. 2021. Garfield County tracked avian data.
Available https://cnhp.colostate.edu/ (Accessed April 12, 2021).
Lambeck, R. J. 1997. Focal Species: A Multi-Species Umbrella for Nature Conservation.
Conservation Biology. 11:849.
NatureServe. 2021. NatureServe Explorer [web application]. NatureServe, Arlington,
Virginia. Available https://explorer.natureserve.org/. (Accessed: April 19, 2021).
Robbins, Chandler S. et al. 1983. A Guide to Field Identification—Birds of North
America. Golden Press. New York.
Roberge, J.M., and P. Angelstam. 2004. Usefulness of the Umbrella species Concept as a
Conservation Tool. Conservation Biology. 18:76-85.
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Table 1: Common plants found on the North Hang’s Ranch study area.
ID Scientific Name Common Name Indicator Status Stratum
1 Carex nebraskensis Nebraska Sedge OBL H
2 Carex microptera Small-Wing Sedge FACU H
3 Carex utriculata Beaked Sedge OBL H
4 Beckmannia schyzachne Sloughgrass FACW H
5 Scirpus americanus Three-Square Bulrush OBL H
6 Eleocharis macrostachya Creeping Spikerush FACW H
7 Typha latifolia Broadleaf Cattail OBL H
8 Agropyron elongatum Intermediate Wheatgrass FACU H
9 Dactylis glomerata Orchardgrass FACU H
10 Bromus inermis Smooth Brome FACU H
11 Trifolium repens White Clover FACU H
12 Trifolium hybridum Alsike Clover FAC- H
13 Phleum pratense Timothy FACU H
14 Poa pratensis Kentucky Bluegrass FAC H
15 Agrostis stolonifera Redtop Bentgrass FAC H
16 Melilotus officinalis Sweetclover FACU H
17 Phalaris arundinacea Reed Canarygrass FACW H
18 Equisetum hyemale Tall Scouring Rush FACW H
19 Carex praegracilis Clustered Field Sedge FACW H
20 Rumex crispus Curly Dock FACW H
21 Juncus arcticus Arctic Rush FACW H
22 Festuca rubra Red Fescue FAC H
23 Elymus repens Quackgrass FACU H
24 Carex aquatilus Water Sedge OBL H
25 Rosa woodsii Wood’s Rose FAC S
26 Agropyron cristatum Crested Wheatgrass UPL H
27 Taraxicum officinale Dandelion FACU+ H
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28 Kochia scoparia Kochia FACU H
29 Populus fremontii Fremont Cottonwood FAC T
30 Clematis ligustifolia Western Virgins Bower FACU V
31 Alopecurus aequalis Short-Awn Foxtail OBL H
32 Rhus trilobata Skunkbush Sumac FAC S
33 Crataegus erythropoda Western Hawthorn FAC T
34 Cirsium arvense Canada Thistle FAC H
35 Distichlis spicata Inland Saltgrass FAC H
36 Populus angustifolia Narrowleaf Cottonwood FACW T
37 Artemisia tridentata Big Sagebrush UPL S
38 Sarcobatus vermiculatus Greasewood UPL S
39 Grindelia squarrosa Curlycup Gumweed FACU H
40 Lactuca serriola Prickly Lettuce FACU H
41 Festuca scabrella Rough Fescue UPL H
42 Cynoglossum officinale Houndstongue FACU H
43 Carduus acanthoides Plumeless Thistle FACU H
44 Arctium minus Burdock FACU H
45 Elaeagnus angustifolia Russian Olive FAC T
46 Salix planifolia Planeleaf Willow OBL S
47 Sphaeralcea coccinea Orange Globemallow UPL H
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8.0 Photographic Documentation of Existing Conditions
Photo 1: Typical upland pasture under flood irrigation on the southern end of Property.
Photo facing northwest, with I-70 just out of the picture to the left.
Photo 2: Sagebrush-dominated uplands on the northwestern corner of the Property.
Photo facing west, Colorado River just out of picture to right.
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Photo 3: Mature cottonwood gallery with many dead-standing trees. Note massive
Russian olive infestation in the understory.
Photo 4: View of Bernudy Ditch facing west just below the headgate on the Colorado
River. Note severe infestation of Russian olives throughout the site and the lack of
cottonwood sapling establishment.
NORTH HANGS RANCH
WETLAND JD
Environmental Solutions, Inc.
600CR216
Riffe, CO 81650
Phone: (970) 618-6841
Fax· (970) 625-1673
sieve.dahmer@esinc.biz
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