REFUGE AND RESOURCE DESCRIPTIONS

chapter 3
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 25

3.1. INTRODUCTION

This chapter describes the environmental resources at

Rocky Flats that may be affected by the implementation of

the Comprehensive Conservation Plan. As discussed

elsewhere in this document, DOE will retain primary

jurisdiction over an area in the center of the Refuge that

encompasses the former Industrial Area and any cleanup,

closure and monitoring facilities. The resource

descriptions and acreage measurements in this chapter

encompass the entire Rocky Flats site and do not

distinguish between Refuge lands and land that will be

retained by DOE for long-term monitoring. 

3.2. GEOLOGY AND SOILS

The 6,240-acre Rocky Flats site is at the interface of the

Great Plains and Rocky Mountains, about 2 miles east of

the foothill escarpment in Jefferson County, Colorado. Site

elevation ranges from 5,500 feet in the southeastern

corner to 6,200 feet near the current west entrance gate.

The western half of the site is characterized by the

relatively flat Rocky Flats pediment, which gives way to

several finger-like drainages that slope down to the rolling

plains in the eastern portion of the site.

SURFICIAL AND BEDROCK GEOLOGY

Geologic units at the Rocky Flats site range from

unconsolidated surficial deposits to various bedrock layers.

Surficial deposits in the western portions of the site are

characterized by the Rocky Flats Alluvium, clayey and

sandy gravels up to 100 feet thick (Figure 5). The steeper

slopes below the Rocky Flats Alluvium in the central

portion of the site generally consist of landslide deposits.

Surficial deposits in the eastern portion of the site consist

of colluvium 3 to 15 feet thick and terrace alluvium 10 to

20 feet thick (Shroba and Carrara 1996).

The Rocky Flats Alluvium is underlain by the Arapahoe

Formation, composed of sandstones, siltstones and

claystones that range from 0 to 50 feet thick. In several

locations, springs emerge at the contact of the Rocky Flats

Alluvium and the Arapahoe Formation. These springs

support the tall upland shrubland community described in

the Vegetation Communities section. 

Beneath the Arapahoe Formation lies the Laramie

Formation, composed of 600 to 800 feet of silty to clayey

sandstones, clayey siltstones and claystones. The Laramie

Formation is underlain by the Fox Hills Sandstone and

Pierre Shale. 

GEOLOGIC HAZARDS

Landslides and landslide deposits are common along

the steep hillsides and incised drainages at the base of

the Rocky Flats Alluvium escarpment. These deposits

occur in areas where bedrock layers such as the

Arapahoe Formation are capped by unconsolidated

gravel formations such as the Rocky Flats Alluvium.

While most of the landslide deposits are of Pleistocene

origin, some, especially those in the Rock Creek

drainage, are likely more recent. Many landslide areas

have high swell potential and are subject to sheet wash

and soil creep (Shroba and Carrara 1996). 

Seven geologic fault lines have been identified at Rocky

Flats, including a northeast-trending reverse fault that

extends across the western part of the Industrial Area.

These faults are not believed to be a concern associated

with current or future human activities or facilities at the

site (DOE 1997).

MINERAL RESOURCES

The Rocky Flats Alluvium is believed to be the only

mineral resource feasible for development at the Refuge.

Historically, uranium, coal, oil and natural gas have been

extracted near the Rocky Flats site. None of these mineral

resources, however, appear to be feasible for development

(DOE 1997). Mining rights and permits at the site are

described in the Infrastructure, Easements and

Utilities section.

Chapter 3. Refuge and Resource Descriptions

The gravelly soils of Rocky Flats have been mined

for decades.

© USFWS
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 27

SOILS

The soils at the site formed from alluvium (stream

deposited), colluvium (gravity deposited), or residuum

(exposed bedrock material). Soils in the western half of the

site formed from alluvium, while those in the eastern half of

the site formed from colluvium and residuum. 

Soils in the western half of the site are primarily the

Flatirons and Nederland soils that formed in the Rocky

Flats Alluvium (Figure 5). Flatirons soils consist of very

cobbly to very stony loamy surface soils and clayey

subsoils. These soils are deep and well drained. Flatirons

soils are located on western pediments and ridgetops, as

well as the upper portions of hillsides. Nederland soils

have very cobbly loamy surface and subsoils. They are

deep and well drained. Nederland soils are located on

steeper hillsides and valley slopes in the western portion

of Rocky Flats.

Soils in the eastern portion of the site consist primarily of

Denver, Kutch, Midway, Valmont, Haverson and Nunn

soils. The Denver-Kutch-Midway complex consists of soils

with loamy surfaces and clayey subsoils. The Denver soils

are deep and well drained, the Kutch soils are moderately

deep and well drained, while Midway soils are shallow and

well drained. The Denver-Kutch-Midway complex is the

dominant soil map unit in the eastern portion of Rocky

Flats, although it also occurs in the western half along

hillsides. Denver and Kutch soils are found on side slopes

and the Midway soils occur on steeper slopes. Valmont

soils consist of deep, well-drained soils with loamy surface

soils and loamy to clayey subsoils. This soil type is found

in the northeast corner of Rocky Flats on the eastward

extension of the Rock Creek/Walnut Creek drainage

divide. Haverson soils are loamy soils located in

floodplains or low terraces. Nunn soils consist of deep,

well-drained soils on lower slopes adjacent to drainage

bottoms. They have loamy surface soils and loamy to

clayey subsoils.

SOIL CONTAMINATION

DOE Retained Area 

Elevated concentrations of plutonium and americium are

currently found in the eastern portion of the site.

Concentrations are highest within the DOE retained area,

adjacent to an area known as the 903 Pad (DOE 1997).

The 903 Pad was an area where industrial oil mixed with

plutonium was stored in steel drums from 1958 to 1968.

This mixture leaked onto the soils in the storage area, and

these contaminated soils were subsequently blown by the

wind and deposited to the east and southeast. In 1968,

the storage area was capped with asphalt to prevent

further release of contaminated soils. Because the area

near the 903 Pad hadplutonium concentrations greater

than 50 pCi/g, DOE removed all surface soils with a

plutonium concentration greater than 50 pCi/g (as well as

some other areas) and replaced them with

uncontaminated soils. It is anticipated that DOE will

retain jurisdiction over the area, which will not be open for

public use.

Refuge Lands 

Existing concentrations of plutonium, the primary

contaminant found in soils outside the DOE retained area,

are very low (less than 7 pCi/g) in the surface soils in the

lands to be transferred to the Service. Most of the Refuge

surface soils have a plutonium concentration less than 1

pCi/g (Figure 3). As discussed in Chapter 1, DOE is

anticipating retaining management responsibility for all

lands with surface soils having a plutonium concentration

more than approximately 7 pCi/g, in order to minimize

the potential for erosion and surface water impacts

(Figure 3). Some surface soils south of the east entrance

road have a plutonium concentration between 1 and 7

pCi/g (Figure 3). Because plutonium was distributed east

of the 903 Pad by wind, and because of the environmental

characteristics of plutonium, elevated plutonium

concentrations are limited to surface soils on the Refuge,

and are not present in subsurface soils. 

The DOE does not anticipate transferring any lands for use

as a refuge that would require additional safety

requirements for either the refuge worker or the visitor.

Lands that would require use restrictions will not be

transferred to the Service for the Refuge. The risk

assessment efforts that resulted in the 50 pCi/g cleanup

action level were inclusive of Refuge management activities

such as trail building, fence construction and maintenance,

visitor use, and prescribed fire and were designed to be

safe for the Refuge worker, Refuge visitors, including

children, and the greater community. 

3.3. WATER RESOURCES

SURFACE WATER

Three drainages originate on or near Rocky Flats: Rock

Creek, Walnut Creek, and Woman Creek (Figure 7).

Stream levels fluctuate depending on the season and

amount of precipitation. Most streamflow is controlled by

ground water discharge; streamflow is higher when

ground water levels are higher, such as in the spring.

Surface sheet flow is only a significant contributor to

stream flows during high precipitation events (Kaiser-Hill

2002b).
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 29

There are currently 16 ponds on the Rocky Flats site, 12 of

which are within the area that will be retained by DOE. The

others are the two Lindsay Ponds on Rock Creek and ponds

D-1 and D-2 on the Smart Ditch. 

Rock Creek

The Rock Creek basin drains the northwest portion of the

site. This drainage has a relatively flat headwater area to

the west and steep gullies and channels to the east where

it cuts below the Rocky Flats Alluvium into bedrock

formations. Rock Creek is hydrologically isolated from the

rest of the site and receives no water from the Industrial

Area. Surface water generally originates from

precipitation and shallow ground water discharge. Rock

Creek continues off-site to the northeast, where it joins

Coal Creek in the Boulder Creek basin (DOE 1997).

Walnut Creek

Walnut Creek consists of three tributaries that drain the

central portion of the site, including most of the Industrial

Area. The northernmost branch, No Name Gulch, begins

at the outfall of the East Landfill Pond. The central

branch, North Walnut Creek, begin at the northern edge

of the Industrial Area and flow through the “A” series

ponds. South Walnut Creek begins in the Industrial Area

and used to collect discharge from the Rocky Flats

Wastewater Treatment Plant before flowing through the

“B” series ponds. The three branches converge near the

eastern Rocky Flats boundary before flowing off-site to

the east. Walnut Creek is typically dry during most of the

year.

Woman Creek

The Woman Creek basin drains the southern portion of

the Rocky Flats site. The Woman Creek drainage consists

of two major branches that begin off of the Rocky Flats

site to the southwest. The main stem of Woman Creek

flows across the site, passing south of the Industrial Area

and flowing through the C-1 pond. The Mower Ditch

diverts most of the Woman Creek flow into Mower

Reservoir, east of Rocky Flats. 

Typically, Woman Creek has no streamflow in late

spring and summer. All surface flows are lost to ground

water in the warmer months. In the winter, most of the

baseflow is from Antelope Springs. Woman Creek is

largely unaffected by pond releases (pond C-2 is

discharged about once a year, with a release of 38 acrefeet). 

Big Dry Creek

A small portion of Rocky Flats near its southern boundary

lies within the Big Dry Creek drainage, although the

creek itself does not flow onto the site. Big Dry Creek

flows into Standley Lake about 1 mile east of Indiana

Street.

Ditches

Besides the three principal drainages, several ditches

cross the site. The South Interceptor Ditch currently

collects runoff from south of the Industrial Area, which

channels surface runoff into the C-2 pond. The Smart

Ditch originates at Rocky Flats Lake to the southwest of

the site, enters Rocky Flats and flows through the South

Woman Creek drainage for almost 2 miles before splitting

off toward Standley Lake to the southeast. The Mower

Ditch diverts most of Woman Creek toward Mower

Reservoir to the east. The Upper Church Ditch enters

Rocky Flats from the west and traverses the Rock

Creek/Walnut Creek drainage divide until it exits the site

in the northeast corner. The McKay Ditch runs from the

west side of the Industrial Area into the Walnut Creek

drainage. The Kinnear Ditch diverts water from Coal

Creek west of Rocky Flats and conveys it to the Woman

Creek channel (Advanced Sciences 1991).

Off-Site Surface Water

Standley Lake is a large water supply reservoir that

serves nearby communities. It is located about 1 mile

southeast of Rocky Flats on the mainstem of Big Dry

Creek (Figure 7). Upstream of Standley Lake just east of

the Rocky Flats site, the Woman Creek Reservoir was

constructed to intercept any Woman Creek flows that are

not diverted through the Mower Ditch. This reservoir is

intended to protect water quality in Standley Lake. Mower

Reservoir is located north of Woman Creek Reservoir on

the east side of Indiana Street and receives Woman Creek

water through the Mower Ditch. 

Drainages such as Rock Creek are prominent features

of the Refuge.

© Shapins Associates
Chapter 3: Refuge and Resource Descriptions

30 Rocky Flats National Wildlife Refuge 

Immediately east of the site lies Great Western Reservoir,

owned by the City and County of Broomfield and used for

irrigation. Rocky Flats Lake lies to the south and west of

the site on land owned by the State of Colorado. Rocky

Flats Lake provides water to the Smart Ditch, which runs

across the southern end of the site toward the D-2 pond

and eventually, into Standley Lake.

GROUND WATER

Hydrogeology at the Rocky Flats site is characterized by

three distinct units: the upper alluvial aquifer, lower

aquitard, and the Laramie-Fox Hills aquifer. An aquifer is

a geologic formation that has sufficient permeability to

store and/or convey water. An aquitard is a confining layer

with low permeability that can store of water but does not

allow water to readily pass through it.

The upper alluvial aquifer is comprised of the

unconsolidated materials that can be as much as 100 feet

thick in the western portions of Rocky Flats. This aquifer

is generally recharged from precipitation or surface water.

Ground water in the unconsolidated alluvial aquifer is

generally close to the land surface, with an average depth

of 11 feet below ground surface. 

Several springs have emerged in areas where the contact

of the upper aquifer and the lower aquitard is exposed at

the surface. While most of these springs occur within the

Rock Creek drainage, Antelope Springs in the Woman

Creek drainage has the largest discharge at the site.

Antelope Springs discharges continuously over several

acres.

The lower aquitard is composed of the deeper claystones

and siltstones of the Laramie and Arapahoe Formations.

Combined, these formations combined are up to 800 feet

thick below Rocky Flats. Recharge of the lower aquitard

occurs from downward flow through the upper aquifer, or

directly through precipitation in areas where the bedrock

is exposed. Beneath the aquitard lies the regional

Laramie-Fox Hills aquifer. It is composed of the lower

sandstone unit of the Laramie Formation and the Fox

Hills Sandstone and is confined by the overlying aquitard.

Ground water levels in the bedrock aquifers are generally

greater than 100 feet (DOE 1997).

Several portions of the upper alluvial aquifer east and

northeast of the Industrial Area are known or suspected

of being contaminated with radionuclides, volatile organic

compounds, and metals. The aquitard is less contaminated

than the upper alluvial aquifer. No contaminant plumes

have been identified in the aquitard. The Laramie-Fox

Hills aquifer beneath the site is unlikely to be

contaminated (IATTF 1998).

Surface water is stored in small ponds in many places on the Refuge.

© RFETS
Chapter 3: Refuge and Resource Descriptions

32 Rocky Flats National Wildlife Refuge 

FUTURE HYDROLOGICAL CONDITIONS

During site closure, DOE will remove the buildings,

pavement and some of the subsurface utilities (to a depth

of 3 feet) from the Industrial Area and grade and

revegetate the area. Subsurface utilities below 3 feet deep

will be assessed individually and may be left in place.

Landfill areas will be covered and also will be regraded.

These changes will affect the surface and ground water

hydrology of the site. The following changes that will alter

the hydrology of the Rocky Flats site are expected to

occur (Kaiser-Hill 2002b):

• No more water will be imported to the site

• Two channels in the Industrial Area will route

water to the A- and B-series ponds

• Treatment plant discharge to pond B-3 will be

discontinued

• The upper reach of the South Interceptor Ditch

will be removed

• Subsurface drains in the Industrial Area will

be removed down to 3 feet

• Subsurface utilities within 3 feet of surface will

be removed and the area will be backfilled

with Rocky Flats Alluvium, changing the

hydraulic conductivity of the subsurface in the

Industrial Area

• Pavement and buildings will be removed in the

Industrial Area (some basement slabs and

walls will be left in place)

• The Industrial Area and landfill areas will be

regraded to match adjacent topography and

the sites will be vegetated

Expected changes in streamflow in Walnut and Woman

creeks are discussed in the following sections. Flow in

Rock Creek will not be affected. These changes will occur

during site cleanup and closure before Refuge

establishment. Any potential impacts from these changes

will occur while the site is under the DOE’s jurisdiction

and are outside of the scope of this CCP/EIS.

Walnut Creek

Walnut Creek flows will change due to the elimination of

waste water treatment plant discharge to the creek, the

removal of impervious areas in the Industrial Area, and

the elimination of storm water drain discharges in the

Industrial Area. Terminal pond (A-4 and B-5) discharges

will decrease and Walnut Creek flows will be dominated

by pond discharge operations and any pond routing or

structural modifications. South Walnut Creek east of the

Industrial Area is estimated to lose 90% of its annual flow

(Kaiser-Hill 2002b).

Woman Creek

Changes in the flow of Woman Creek will be

insignificant, except for the area south of the Original

Landfill where flows may decrease due to the possible

use of covers and slurry walls at the landfill site.

Drainage to the South Interceptor Ditch and baseflow

within the ditch will decrease because storm water flows

from the Industrial Area will be significantly reduced.

Changes in ditch flows, however, are not likely to affect

Woman Creek flows because water from the ditch is

detained in pond C-2 and the ditch supplies less than 10%

of the flow of Woman Creek at the east boundary. 

3.4. VEGETATION COMMUNITIES

A diverse mosaic of vegetation communities is found at

Rocky Flats (Table 3). Two of these vegetation

communities, the xeric tallgrass grassland and the tall

upland shrubland, are considered to be rare in the region.

Other significant vegetation communities include the

riparian woodland, riparian shrubland, wetlands, mesic

mixed grassland, xeric needle and thread grassland,

reclaimed mixed grassland and ponderosa pine woodland

(Figure 8).

Vegetation communities at Rocky Flats have been grouped

into Resource Management Zones. These zones generalize

the Refuge into three categories with similar wildlife

habitat attributes and management requirements. The

three management zones are Xeric Tallgrass Grassland,

Wetlands and Riparian Corridors, and Mixed Prairie

Grasslands. 

XERIC TALLGRASS GRASSLAND MANAGEMENT ZONE

Xeric Tallgrass Grassland

This rare plant community is found on the rocky plains

in the western portions of the site, extending eastward

along several finger-like ridgelines. Covering 1,568 acres,

it contains several different plant associations that

include combinations of big bluestem, little bluestem,

mountain muhly, sun sedge, Fendler’s sandwort and

Porter’s aster. Other tallgrass prairie species include

Indian-grass, prairie dropseed, switchgrass, and needleand-thread grass. Species richness is high; 285 species

have been recorded within the xeric tallgrass community

at Rocky Flats, of which about 80% are native.
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 33

Differences in species composition are attributable to

annual variations in climate and precipitation (Kaiser-Hill

2002c).

The xeric tallgrass grassland is found primarily on

Flatirons and Nederland soils and is believed to be a relict

once connected to the tallgrass prairie hundreds of miles

to the east (Nelson 2003; Essington et al. 1996).

The Colorado Natural Heritage Program (CNHP) has

found that much of the xeric tallgrass grasslands along the

Colorado Front Range has been disturbed by urban

development and agricultural conversion over the last

century. In addition, aggressive weed species such as

cheatgrass, Japanese brome and diffuse knapweed have

degraded many areas of this community throughout the

region (Essington et al. 1996). The CNHP believes that the

xeric tallgrass grassland community exists in fewer than

20 places globally and that Rocky Flats has the largest

example of this community remaining in Colorado and

perhaps North America. The CNHP ranks this community

as imperiled within the state (Essington et al. 1996).

The xeric tallgrass grassland community is comprised of

several sub-communities (Nelson 2003). One of these subcommunities was identified by ESCO during a five-year

evaluation of bluestem-dominated grasslands in the Rocky

Flats area. This study found that the major distinguishing

feature of what ESCO calls the rare “Rocky Flats Bluestem

Grassland” community is the abundance of big bluestem

with little bluestem, mountain muhly and Porter’s aster.

While big and little bluestem are characteristic of

Midwestern tallgrass prairies, mountain muhly and

Porter’s aster are characteristic of mountain environments.

This unusual combination of mountain and plains grassland

species in a consistent and recurring pattern across the

Rocky Flats alluvial surface, along with evidence of

exceptional stability, makes this vegetation community a

rare, if not unique, resource (ESCO 2002).

In 2001, high winds deposited several inches of sand on

xeric tallgrass grassland areas adjacent to existing gravel

mines in the northwest corner of the Refuge. This sand

buried most of the native vegetation and was soon

colonized by sunflower, a native annual weedy species, as

Big bluestem within the xeric tallgrass grassland. well as noxious weeds such as diffuse knapweed, Russian

© USFWS

Table 3. Vegetation Communities at Rocky Flats

Vegetation Community

Grasslands

Xeric Tallgrass Grassland

Mesic Mixed Grassland

Xeric Needle and Thread Grassland

Reclaimed Mixed Grassland

Short Grassland

Shrublands

Tall Upland Shrubland

Riparian Shrubland

Other Shrubland

Total

Acres

1,568

2,199

187

640

10

34

41

70

Vegetation Community

Woodlands

Riparian Woodland

Ponderosa Pine Woodland

Wetlands

Tall Marsh Wetland

Short Marsh Wetland

Wet Meadow

Open Water/Mudflats

Other

Disturbed and Developed Areas

Acres

28

9

31

121

254

51

997

6,240
Chapter 3: Refuge and Resource Descriptions

34 Rocky Flats National Wildlife Refuge 

thistle and kochia. This area may require ongoing weed

management and possible reseeding to re-establish the

native vegetative cover (Kaiser-Hill 2002c).

WETLAND AND RIPARIAN CORRIDORS

MANAGEMENT ZONE

Riparian Woodland

The riparian woodland community is characterized by a

diverse mixture of plains cottonwood, peachleaf willow,

Siberian elm and coyote willow, with an understory of

various shrubs such as leadplant and snowberry. Covering

28 acres, it is found primarily along the drainage bottoms

of Rocky Flats, with the most significant stand occurring

in the Rock Creek drainage (Kaiser-Hill 1997; PTI 1997;

Essington et al. 1996). 

The most significant threat to the riparian woodland

community is from exotic species such as Siberian elm,

Canada thistle, musk thistle, smooth brome and Kentucky

bluegrass. Preservation of this woodland community

depends on the preservation of associated streamflow

(PTI 1997; Essington et al. 1996). 

Riparian Shrubland

Riparian shrubland forms extensive, dense thickets of

shrubs along the stream bottoms. This community

covers 41 acres throughout the Rocky Flats site. It is

dominated by narrowleaf willow, coyote willow, or

indigo bush and generally has an understory consisting

of leadplant, Baltic rush and various sedges (Kettler et

al. 1994; USACE 1994; Kaiser-Hill 1997).

Tall Upland Shrubland

Tall upland shrubland occurs on 34 acres of north-facing

slopes above seeps and along streams, primarily within

the Rock Creek drainage. The tall upland shrubland

consists of a rare association of hawthorn, chokecherry

and occasionally wild plum. This shrubland is associated

with ground water seeps that form at the contact of the

Rocky Flats Alluvium and the underlying, relatively

impermeable Arapahoe Formation. The herbaceous

understory contains a number of species that are

restricted to the cool, shaded microhabitat provided by the

canopy. Understory species include Fendler waterleaf,

spreading sweetroot, anise root, carrionflower greenbriar,

fragile fern, Colorado violet, Rydberg’s violet and

northern bedstraw. Although the tall upland shrubland

represents less than 1% of the total area of Rocky Flats, it

contains 55% of the plant species on the site (DOE/Service

2001). This shrubland community is believed to be rare

© USFWS

Choke cherry within the tall upland shrub habitat.

© USFWS

Tall upland shrubland occur on slopes above seeps and

along streams.
Chapter 3: Refuge and Resource Descriptions

36 Rocky Flats National Wildlife Refuge 

and may not occur anywhere else (DOE/Service 2001;

Essington et al. 1996).

Other Shrubland

Other shrubland communities include short upland

shrubland and savannah shrubland, covering 70 acres

primarily in the Rock Creek drainage. Short upland

shrubland is characterized by stands of snowberry and

occasional Wood’s rose and is often found in association

with wet meadows and other wetland or riparian

communities. Savanna shrubland occurs in dryer areas

where scattered shrubs are interspersed with

grasslands. Three-leaf sumac is the predominant shrub

in this community (Kaiser-Hill 1997). 

Wetland Communities

Wetland communities cover 406 acres of the Rocky Flats

site and play an important role in sustaining the diverse

vegetation and habitat types found on the site. The most

significant wetland complexes at Rocky Flats are the

seep-fed wetlands along the hillsides of the Rock Creek

drainage and the Antelope Springs complex in the

Woman Creek drainage. These wetlands are significant

because they have the largest contiguous areas and the

most complex plant associations (PTI 1997).

Three wetland types, tall marsh, short marsh and wet

meadow, are found at the site. These wetland types occur

in streamside areas along the valley floors and near the

seeps and springs that occur along many of the hillsides.

Each wetland type is described below. 

Tall Marsh Wetland

Tall marsh wetlands generally occur along ponds, ditches

and in persistently saturated seeps. Covering 31 acres of

the site, these wetlands are dominated by cattails,

bulrushes and associated forbs such as watercress, showy

milkweed, swamp milkweed and Canada thistle (a noxious

weed). Antelope Springs in the Woman Creek drainage is

the best example of a saturated slope wetland and tall

marsh community at Rocky Flats (Figure 8).

Short Marsh Wetland

Covering 121 acres, this wetland type is commonly

associated with seasonally inundated or saturated areas,

such as hillside seeps. Prevalent species include Nebraska

sedge, Baltic rush and spike rush as well as forbs such as

watercress and speedwell. 

Wet Meadow Wetland

These seasonally saturated wetlands occupy 254 acres on

the perimeter of saturated wetlands and contain elements

of both the short marsh wetland and upland mixed

grassland communities. Prevalent species include redtop,

prairie cordgrass and solid stands of Canada bluegrass

and western wheatgrass. Other species commonly found

in this community include common milkweed, wild iris,

Canada thistle, dock and occasionally arnica (Nelson 2003).

MIXED PRAIRIE GRASSLANDS MANAGEMENT ZONE

Mesic Mixed Grassland

The mesic mixed grassland community is the largest

vegetation community at Rocky Flats, covering 2,199 acres

across the broad ridges, hillsides and valley floors

throughout the site and the rolling plains in the eastern

portions of Rocky Flats (Figure 8). This community is

characterized by western wheatgrass, blue grama, sideoats grama, prairie junegrass, Canada bluegrass,

Kentucky bluegrass, green needlegrass and little

bluestem. This grassland occurs on clay loam soils having

relatively higher soil moisture content than other upland

areas. The higher moisture results from subirrigation

from the coarse alluvial soils, snow accumulation, and

protection from wind (DOE 1997). The mesic mixed

grassland is very important to wildlife species including

grassland birds, small mammals and larger mammals such

as mule deer.

The quality of mesic mixed grassland varies considerably

across the site. In the western parts of the site, this

community has been degraded by diffuse knapweed, while

some areas in the eastern portion of the site have been

degraded by weed species such as Japanese brome,

alyssum and musk thistle (PTI 1997).

Wetlands and open water provide waterfowl habitat.

© Mauro
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 37

Xeric Needle and Thread Grassland 

Several patches of xeric grassland dominated by needleand-thread grass occur in the eastern half of Rocky Flats.

These patches cover 187 acres. Other dominant grass

species include New Mexico feathergrass, Canada

bluegrass, Kentucky bluegrass and Japanese brome

(Nelson 2003). This grassland occurs primarily on the

eastern extensions of the Rocky Flats pediment that is

characterized by very cobbly sandy loam soils. Although

not quite as cobbly, these soils are very similar to the soils

that support the xeric tallgrass grassland community

(Kaiser-Hill 1997). The largest expanse of needle-andthread grassland at Rocky Flats occurs along the ridgetop

north of the east access road. 

Reclaimed Mixed Grassland

Reclaimed mixed grassland covers 640 acres, primarily

in the southeastern portion of the site which was

formerly cultivated for agriculture. Most of these areas

have been re-seeded with a mixture of smooth brome

and intermediate wheatgrass, both introduced species.

Other common species include crested wheatgrass,

sweetclover and field bindweed (Kaiser-Hill 1997). 

Short Grassland

This grassland is typified by buffalograss and blue

grama, both short grass prairie species. Ten acres

of this community are found on the site (Kaiser-Hill

1997).

Ponderosa Pine Woodland

Isolated patches of ponderosa pine woodland cover 9 acres

in the uppermost reaches of the Rock Creek and Woman

Creek drainages near the western edge of the Refuge.

These scattered pines represent an eastward extension of

the nearby foothills forests. While much of the understory

is similar to the adjacent grassland communities, other

associated plants are more likely to occur in foothills

environments (DOE 1997).

Disturbed and Developed Areas

Disturbed and developed areas consist of existing or

former facilities associated with the previous use of the

Rocky Flats site. They include roads, landfills, dams and

other facilities. They also include former facilities that have

been revegetated with native and introduced grass species.

NOXIOUS WEEDS

Noxious weeds are exotic, aggressive plants that invade

native habitat and cause adverse economic or

environmental impacts. Since 1990, Rocky Flats has

experienced a large increase in noxious weeds (DOE

1997). At Rocky Flats, the noxious weed species with the

greatest potential to degrade the native plant communities

and that are the most difficult to control include diffuse

knapweed, musk thistle, Dalmatian toadflax, and Canada

thistle. Other increasingly problematic weeds are downy

brome (cheatgrass), field bindweed, and jointed goatgrass

(Lane 2004). Diffuse knapweed, an aggressive

tumbleweed, is currently given highest control priority.

Canada thistle is common in and around most of the

wetlands, musk thistle is found across mesic grasslands,

and Dalmatian toadflax is common in xeric grasslands and

other areas (Figure 9). Sulfur cinquefoil is a new invader

to the area that may have already established populations

on the Refuge (Lane 2004). 

Prioritized noxious weed lists and selected weed control

measures are found in the 2002 Annual Vegetation

Management Plan. The three most abundant noxious

weeds identified in 2001 mapping were: Dalmatian

toadflax infesting 2,504 acres; diffuse knapweed infesting

1,919 acres; and musk thistle infesting 869 acres (Table 4)

(Kaiser-Hill 2002a; DOE/Service 2001).

RARE PLANTS

No federally listed plant species, such as the Ute ladies’-

tresses orchid or Colorado butterfly plant, are known to

occur at Rocky Flats. Aside from the rare xeric tallgrass

prairie and tall upland shrubland communities, Rocky

Flats also supports populations of four rare plant species

that are listed as rare or imperiled by the CNHP. These

species are the mountain-loving sedge, forktip three-awn,

carrionflower greenbriar, and dwarf wild indigo. Forktip

three-awn primarily occurs in previously disturbed sites

near the western edge of the current Industrial Area. The

other three species occur primarily along the pediment

slopes in the Rock Creek drainage (Kaiser-Hill 2002c).

Dalmatian toadflax, a noxious weed, has moved into

large areas of the Refuge.

© Mauro
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 39

FIRE HISTORY

Historical documentation indicates that the grasslands in

the Rocky Flats area have been subjected to lightning and

human-caused fires for thousands of years (DOE 1999).

These fires likely played a major role in promoting native

vegetation growth and diversity (DOE 1999). Since 1972,

wildfires have not been allowed to burn and only one

controlled burn has been conducted in the grasslands at

Rocky Flats. As a result, a fuel load of dead vegetation has

been building up in the grasslands of Rocky Flats for at

least 30 years. This buildup of dead vegetation has

contributed to an invasion of noxious weeds on the site,

particularly in the last 10 years (DOE 1999). 

Seven wildfires have been documented on the site since

1993 (Figure 10). In 1994, the Spring Grassland fire

burned 70 acres between Highway 128 on the north

boundary and the north access road. In 1996, the 104-

acre Labor Day Grassland Fire burned much of an area

penned in by access roads in the southern portion of the

site. In February 2002, a 27-acre fire burned through

portions of the Rock Creek drainage on the south side of

Highway 128. A 48-acre prescribed burn was conducted

on April 6, 2000. The prescribed burn took place in the

same area as the 1996 wildfire (Kaiser-Hill 2002). 

3.5. WILDLIFE RESOURCES

Many areas of the Rocky Flats site have remained

relatively undisturbed for the last 30 to 50 years, allowing

them to retain diverse habitat and associated wildlife.

These wildlife communities are supported by the regional

network of protected open space that surrounds the site

on three sides, buffering wildlife habitat from the

surrounding urban development.

MAMMALS

One of the most abundant and conspicuous mammal

species at Rocky Flats is the mule deer. A resident herd of

about 160 individuals inhabits the site. While mule deer

distribution varies by the season, they appear to have a

general preference for the following areas (shown in

Figure 11):

• The open grasslands of the upper Rock Creek

drainage 

• The shrublands of the lower Rock Creek

drainage

• The grasslands of the upper Walnut Creek

drainage 

• The hillsides above lower Walnut Creek

• Riparian bottomlands around Woman Creek

and Antelope Springs

• The grasslands below the pediment in the

Smart Ditch drainage

Mule deer is one of the most abundant and conspicuous

mammal species on the Refuge.

© Mauro

Table 4. Major Noxious Weeds at Rocky Flats

Weed Name

Dalmatian toadflax

Diffuse knapweed

Musk thistle

High Density

(ac.)

341

380

9

Medium Density

(ac.)

389

525

84

Low Density

(ac.)

1,240

377

430

Scattered

Density (ac.)

537

377

346

Total Infested

Area (ac.)

1,207

1,956

869
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 41

In the spring, mule deer exhibit an affinity for woody

habitat and secondarily for grasslands. In the summer,

deer use is more generally divided among different

habitats. In the fall, mule deer primarily use woody

habitats, with grasslands also being important. In the

winter, mule deer are commonly observed in grasslands

and tall upland shrublands (Kaiser-Hill 2001). 

Whitetail deer have become more common at the site

and are often observed in company with mule deer. The

Refuge is in CDOW’s Game Management Unit (GMU)

#38 and is adjacent to GMU#29, which collectively make

up the Boulder deer herd. American elk visit Rocky

Flats, but are not resident (DOE 1997). In 2003, 11 cow

elk were observed with nine calves in the Rock Creek

drainage (Wedermyer 2003). 

Other mammals observed at Rocky Flats include desert

cottontail, black-tailed jackrabbits, muskrat and

porcupine. Muskrats generally occur in and around the

ponds, while porcupine populations are limited to the

shrubland and ponderosa pine habitats in the upper

Rock Creek drainage (DOE 1997). Black-tailed prairie

dogs inhabit the Rocky Flats site in limited numbers

(Figure 11) and are discussed in greater detail below.

Numerous small mammal species, such as mice and

voles, inhabit all vegetation community types at Rocky

Flats. Preble’s meadow jumping mouse, a threatened

species, is described below under Federal Threatened

and Endangered Species.

Two commonly observed carnivore species at Rocky Flats

are the coyote, which occurs throughout the site, and

raccoon, which is often seen in the Industrial Area and

near watercourses. Typically at Rocky Flats, three to six

coyote dens support an estimated 14 to 16 individuals at

any given time (Kaiser-Hill 2001). Twenty-two coyote dens

used between 1991 and 2002 have been identified at Rocky

Flats. The coyote dens generally occur on hillsides near

watercourses. Six dens were active in 2002. One active

den was located in the upper Rock Creek drainage, two

were located on the slopes above either side of Walnut

Creek near Indiana Street, one was near the D-1 pond,

one near Antelope Springs and one in the upper South

Woman Creek drainage (Nelson 2003). Other carnivores

include striped skunk, gray fox, red fox, long-tailed weasel,

American badger and mink. Black bears and mountain

lion tracks are occasionally seen at the site (Kaiser-Hill

2000, 2001).

Black-Tailed Prairie Dog

The black-tailed prairie dog is a controversial species on

the forefront of conservation in the U.S. (CDOW 2003).

The prairie dog is often described and disputed as a

“keystone species” because it has a large effect on

community structure or ecosystem function (Power et al.

1996; CDOW 2003). 

In August 2004, the Service removed the prairie dog from

consideration as a candidate species under the

Endangered Species Act (Service 2004b). Candidate

species are plants and animals for which the Service has

sufficient information on their biological status to propose

them as endangered or threatened under the ESA, but for

which development of a proposed listing regulation is

precluded by other higher priority listing activities.

Candidate species receive no statutory protection under

the ESA (Service 2002).

Regardless of its status as a keystone species, prairie dogs

play an important role in grassland ecosystems. Several

studies found that prairie dogs alter plant species

composition and structure. Typically, areas occupied by

prairie dogs have greater cover and abundance of

perennial grasses and annual forbs compared to nonThe coyote is a commonly observed carnivore species on the Refuge.

© Mauro
Chapter 3: Refuge and Resource Descriptions

42 Rocky Flats National Wildlife Refuge 

occupied sites (Whicker and Detling 1988; Witmer et al.

2002). Prairie dogs can contribute to overall landscape

heterogeneity, affect nutrient cycling, and provide nest sites

and shelter for wildlife such as rattlesnakes and burrowing

owls (Whicker and Detling 1988). Prairie dogs can also

denude the surface by clipping above-ground vegetation and

contributing to exposed bare ground by digging up roots

(Kuford 1958; Smith 1967). Prairie dogs are susceptible to

and can spread Sylvatic plague.

Three black-tailed prairie dog colonies, comprising 112.8

acres of grasslands, were mapped at Rocky Flats in 2000.

Since 2000, plague outbreaks have reduced the active

colonies to an area of 10 acres (Stone 2003). These colonies

are shown on Figure 11. 

The Rocky Flats site contains about 2,460 acres of potential

prairie dog habitat (Figure 12). Delineations of potential

prairie dog habitat are based on soil, vegetation, and slope

attributes that prairie dogs are known to prefer (Clippinger

1989):

• 30 to 90% herbaceous cover

• 2- to 10-inch vegetation height

• Slopes less than 20% (prefer less than 10%)

• Rock-free soils with less than 70% sand content

BIRDS

The most commonly observed raptors at Rocky Flats are redtailed hawk, great horned owl and American kestrel. Other

less abundant raptors include Swainson’s hawk, ferruginous

hawk, prairie falcon and long-eared owls. Most raptor species

use riparian woodlands or tall upland shrublands for nesting

and roosting habitat and forage in all habitats at the site.

Raptor nest sites observed between 1991 and 1998 are shown

on Figure 11.

Over 185 species of migratory birds have been recorded at

Rocky Flats, of which about 75 are believed to breed at the

site. Of the estimated 100 neotropical migrants (migratory

birds that breed north of the U.S./Mexico border and

winter south of the border (PTI 1997)) at Rocky Flats,

about 45 are confirmed or suspected breeders at the site. 

Commonly observed bird species in wetland habitats

include the red-winged blackbird, song sparrow, common

yellowthroat and common snipe. Common birds in

riparian woodland areas include the northern oriole,

American goldfinch, house finch and yellow warbler. The

tall upland shrubland habitat is inhabited by the song

sparrow, rufus-sided towhee, black-billed magpie, yellowbreasted chat and black-capped chickadee. Common

Swainson’s hawk.

© USFWS

Western meadowlark.

© Mauro

Snipe.

© Mauro
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 45

grassland birds include the vesper sparrow, western

meadowlark, grasshopper sparrow and mourning dove

(DOE 1997). The reclaimed mixed grassland provides

habitat for birds such as the western meadowlark and

vesper sparrow (PTI 1997).

Several waterfowl species use the ponds at Rocky

Flats. The most common waterfowl are mallards and

Canada geese (DOE 1997). Great blue herons feed in

mudflats and short marshlands, while double-crested

cormorants are common summer residents.

Plains Sharp-tailed Grouse

The Rocky Flats site and surrounding areas contain

potential habitat for the plains sharp-tailed grouse. The

grouse is extirpated from the area and is not known to

occur at Rocky Flats prior to 2003 (DOE 1997). The City

of Boulder Open Space and Mountain Parks

Department, along with Boulder County Parks and

Open Space and the CDOW, have initiated a sharp-tailed

grouse reintroduction program on joint City-County

owned open space land north of Rocky Flats. About 25

individuals were transplanted to the open space area in

2003, while several more are planned to be reintroduced

in the future (Brennan 2003). Several of the

transplanted individuals are believed to have used Rocky

Flats’ grasslands (Wedermyer 2003). 

According to the CDOW Plains Sharp-tailed Grouse

Recovery Plan (CDOW 1992), grouse use different

habitats seasonally with extensive use of grassland and

grassland-low shrub transition zones. Riparian areas and

wooded draws are important winter habitat. Reasons for

the decline of sharp-tailed grouse include land cultivation,

livestock grazing and fire control. Other threats to

grouse include urban development and alteration of

habitat by weed infestation (Gershman 1992). 

REPTILES AND AMPHIBIANS

In general, reptiles and amphibians are found in small

numbers at Rocky Flats due to an absence of suitable

habitat. The most common reptiles are the bullsnake,

yellow-bellied racer, plains garter snake and prairie

rattlesnake. All of these species occur in the open

grassland habitats, although the plains garter snake

typically lives close to water bodies. Other reptiles include

the short-horned lizard in open grasslands, the eastern

fence lizard in rocky shrublands, and the western painted

turtle in ponds (DOE 1997).

The most abundant amphibian at Rocky Flats is the boreal

chorus frog, which breeds in water bodies throughout the

site. The northern leopard frog is less common and is

found only in permanent water bodies such as ponds

(DOE 1997). The boreal chorus frog is relatively abundant

in the streams and wetlands at Rocky Flats (Kaiser-Hill

2000). Other amphibians include the bullfrog,

Woodhouse’s toad, the plains spadefoot and the tiger

salamander (DOE 1997). 

AQUATIC SPECIES

Aquatic species at Rocky Flats are limited in drainages

and ditches by low and irregular flows. The most common

aquatic macroinvertebrates (aquatic insects) are the larvae

of the blackfly, midge and mayfly (DOE 1997). Other

species include caddisflies, craneflies, damselfly larvae, as

well as snails and amphipods. Large macroinvertebrates

such as crayfish and snails are potentially important prey

for other fish, waterfowl and mammal species. 

Each of the three primary drainages at Rocky Flats

contains a variety of pond and stream habitats, varying

amounts of habitat modification, and seasonal water flows.

The Walnut Creek drainage has been highly modified as

part of the development of Rocky Flats. The upper section

The western painted turtle is found in ponds on the Refuge.

© MAURO

Northern red-belly dace were introduced into the Lindsay

Pond in 2003.

© RFETS
Chapter 3: Refuge and Resource Descriptions

46 Rocky Flats National Wildlife Refuge 

of the drainage was filled and the lower section modified

into a series of small reservoirs that can retain water

released from the Industrial Area. A variety of non-native

fish species (rainbow trout, carp, bass) were introduced

into the Walnut Creek reservoirs. Although all

introductions did not establish reproducing fish

populations, carp, goldfish and fathead minnows are

present in these reservoirs. Woman Creek retains a

significant amount of stream habitat and holds the

majority of Rocky Flats fish species. Native fish species

that reproduce within Woman Creek include white

suckers, fathead minnows, green sunfish, stonerollers and

creek chubs. Two non-native fish species, golden shiners

and largemouth bass, also are found in the drainage. 

According to the Colorado Vertebrate Ranking System

(CDOW 2001), the Iowa darter and common shiner rank

high enough to merit re-evaluation and the redbelly dace

is potentially imperiled. Threats to these species include

extirpation through habitat degradation (e.g., siltation,

pollution and/or bank destabilization, the effects of

urbanization and predation by introduced non-native fish.

Native Fish Restoration

The 2001 Rock Creek Reserve Integrated Natural

Resources Management Plan (DOE/Service 2001) called

for the establishment of native fish populations within the

Rock Creek drainage. Rock Creek supports favorable

habitat for native fish such as the common shiner and

northern redbelly dace. Monitoring during the drought of

2002 demonstrated that Rock Creek flows remain

consistent in dry years.

Native fish restoration efforts began in 2002, when

largemouth bass and other non-native fish were removed

from the Lindsay Ponds with rotenone (a piscicide). In

June and August 2003, common shiner and northern

redbelly dace were introduced to the Rock Creek

drainage, with the intention of establishing a new

population of these rare and declining native fish species

(Rosenlund 2003). 

WILDLIFE SPECIES OF SPECIAL CONCERN

In addition to federally listed wildlife species described

below in the Federal Threatened and Endangered

Species section, the Rocky Flats site has been known to

support numerous species with special status designated

by CDOW because of their rare or imperiled status (Table

5). Western burrowing owl has been observed in

grasslands and the ferruginous hawk has been observed in

riparian woodlands and open grasslands (PTI 1997;

DOE 1997).

Mule deer are one of several wildlife species that regularly move between the Refuge and adjoining lands.

© Mauro
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 47

WILDLIFE CORRIDORS

While Rocky Flats is surrounded on three sides by major

roads, many wildlife species move between the site and

habitat in surrounding areas. However, movement

corridors between the Refuge and adjacent lands are not

well defined. Movement of most terrestrial species occurs

along broad areas where disturbance and barriers to

movement are minimized (Howard 2003; Wedermyer

2003).

On the west side of the Refuge, east-west movement across

Highway 93 can be impeded by the South Boulder Diversion

Canal and mining areas on the western edge of Rocky Flats.

Given these barriers, the most likely areas for wildlife

movement are the open lands in the upper Rock Creek area

and the upper Woman Creek area between the mining areas

(on land owned by the State of Colorado) and the west

access road.

Prairie dogs cross Highway 128 in the northwest corner of

the Refuge, to access other colonies on adjacent open

space lands. Otherwise, north-south prairie dog movement

across Highway 128 does not likely occur at any specific

location. The Rock Creek drainage along the highway is

impeded by the highway embankment and the culverts for

the creek are too small for use by larger species of

mammals. Likewise, the east side of the Refuge is open in

most places and wildlife moves across a broad front,

although the Walnut Creek and Woman Creek drainages

provide natural corridors for east-west movement for small

and mid-size mammals across Indiana Street.

Most deer on Rocky Flats do not migrate offsite and elk

periodically descend from the foothills and enter Rocky

Flats from the west. In the spring of 2003, several cow elk

used the Rock Creek drainage as a calving ground

(Wedermyer 2003). The behavior of other species is less

known.

POTENTIAL CONTAMINATION ISSUES

Extensive studies have been conducted on the potential

effects of contamination on wildlife and vegetation at

Rocky Flats since the mid 1970s, mostly by Colorado

State University. These studies include two deer studies

as well as studies of small mammals, arthropods

(insects), snakes, and cattle. Samples were taken of

various species for the Draft Ecological Risk

Assessments for Walnut Creek and Woman Creek

Watersheds at Rocky Flats Environmental Technology

Site (September 1995) and included samples consisting The Refuge contains about 2,460 acres of potential

prairie dog habitat.

© USFWS

Table 5. Wildlife Species of State Special Concern at Rocky Flats

Common Name

Plains sharp-tailed grouse

Western burrowing owl

Northern leopard frog

American peregrine falcon 

Common garter snake

Ferruginous hawk

Greater sandhill crane

Long-billed curlew

Mountain plover

Scientific Name

Tympanuchus phasianellus jamesii

Athene cunicularia hypugea

Rana pipiens

Falco peregrinus

Thamnophis sirtalis

Buteo regalis

Grus canadensis tibida

Numenius americanus

Charadrius montanus

Status

State endangered

State threatened

State special concern

State special concern

State special concern

State special concern

State special concern

State special concern

State special concern

Occurrence at 

Rocky Flats

Observed infrequently

Known resident or regular visitor

Known resident

Regular visitor

Observed infrequently

Known resident or regular visitor

Observed infrequently

Observed infrequently

Observed infrequently
Chapter 3: Refuge and Resource Descriptions

48 Rocky Flats National Wildlife Refuge 

of small mammals, insects, benthic invertebrates, and

fish. Additional studies were done by CSU on vegetation

uptake of plutonium, in both terrestrial and aquatic

species. Studies conducted at other DOE facilities can

be used to compare to Rocky Flats. See Section 1.5 -

Issues Outside the Scope of The CCP and EIS, and

Section 3.2 - Geology and Soils for more information

about residual soil contamination at Rocky Flats.

Tissue samples, including edible tissues of deer harvested

at Rocky Flats in 2002, have been analyzed for

contaminants. The results of these analyses indicate

radionuclide tissue levels of non-detectable quantities or at

method detection limits. In all cases the edible tissue

levels are below the 1x10-6 risk-based level for

consumption of Rocky Flats deer tissue.

3.6. FEDERAL THREATENED AND ENDANGERED

SPECIES

Rocky Flats supports two wildlife species listed as

threatened or endangered under the Endangered Species

Act (ESA). The Preble’s meadow jumping mouse and the

bald eagle are listed as threatened. 

As discussed in the preceding Wildlife section, the blacktailed prairie dog is no longer listed as a candidate species

(Service 2004b). 

PREBLE’S MEADOW JUMPING MOUSE

Preble’s meadow jumping mouse (Preble’s) occurs in

every major drainage on the site. Listed as a threatened

species in 1998, the mouse occurs in habitat adjacent to

streams and waterways along the Front Range of

Colorado and southeastern Wyoming. At Rocky Flats,

Preble’s also has been found in wetlands and shrubland

communities adjacent to the Rock Creek and Woman

Creek drainages. Knowledge of the natural history and

ecology of the Preble’s is limited. An increase in

knowledge about the species may change our

understanding of their habitat needs and associations. In

2003, the Service designated critical habitat for the

Preble’s. The critical habitat did not include any of the

drainages at Rocky Flats because the site is to become a

Refuge (Service 2003). 

In February 2005, the Service published a 12-month

petition finding on a proposal to delist the Preble's (Zapus

hudsonius preblei) from the Endangered Species List

based on the results of a study by the Denver Museum of

Nature and Science regarding the genetic makeup of

Preble's (Ramey et al. 2003, 2004).

The Service will make a decision whether to delist within

approximately one year of publishing the proposal. This

decision will be based upon any new information received

regarding combining Preble's with the Bear Lodge

Jumping Mouse (Z.h. campestris), an evaluation of threats

to the combined Z.h. campestris entity, and an evaluation

of whether the Preble's portion of Z.h. campestris qualifies

as a Distinct Population Segment requiring protection.

Until the review and delisting occur, the Service will

continue to manage Preble's as a threatened species in

accordance with existing laws and policies.

BALD EAGLE

The bald eagle occasionally forages at Rocky Flats

although no nests have been identified. An active nest is

located to the east of Rocky Flats near Standley Lake.

Eagles feed primarily on fish and waterbirds but also on

small mammals and mammal carcasses (DOE/Service

2001). The bald eagle was federally listed as endangered

in 1967 and was downlisted to threatened in 1994. 

PLANT SPECIES

No federally listed plant species are known to occur at

Rocky Flats. While many of the riparian and wetland

communities support potential habitat for the Ute ladies’-

tresses orchid and Colorado butterfly plant, these species

are not known to occur at the site (ESCO 1994). The

mosaic of vegetation communities at Rocky Flats contains

several rare and sensitive plant communities. These

include the xeric tallgrass grassland, tall upland

shrubland, riparian shrubland, mountain-loving sedge,

forktip three-awn, carrionflower greenbriar, dwarf wild

indigo and plains cottonwood riparian woodland

Preble’s meadow jumping mouse.

© RFETS
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 49

communities. Each of these communities is described in

detail in the Vegetation Communities section.

3.7. CULTURAL RESOURCES

Cultural resource surveys have identified and recorded 45

cultural sites or artifacts at Rocky Flats (Figure 13). Most

of these sites or artifacts are related to Euro-American

occupation of the area within the last 120 years. None of

the identified cultural resources is recommended as

eligible for listing in the National Register of Historic

Places.

PREHISTORIC RESOURCES

While various Native American groups occupied the

Rocky Flats region prior to 1800, few remains from this

period have been found on the site. Cultural resource

inventories have identified several isolated finds of

prehistoric origin, including stone enclosures and stone

cairns (Dames and Moore 1991).

HISTORIC RESOURCES

Numerous sites and artifacts related to agricultural and

mining activity at Rocky Flats in the early 20th century

have been identified. These include ditches, stock ponds,

rock piles, building remains, fencing materials and other

farming and ranching-related equipment (Figure 13).

Remnants of an apple orchard are near the site of a

former stage coach stop in the Woman Creek drainage.

An abandoned railroad grade, whose construction began

in 1881 and was never completed, traverses the Refuge.

Many historic sites relate to land uses at Rocky Flats

during the early 20th century. During this time, the cattle

industry along the Front Range boomed and several

families acquired land for pasture in the Rocky Flats area.

In most cases, the primary ranch sites were outside of

what became the Rocky Flats site, with the exception of

the Lindsay Ranch (Dames and Moore 1991).

Lindsay Ranch

The area known as the Lindsay Ranch was originally

homesteaded by the Scott family in 1868. The northern

part of this area was given to the railroad in 1897 as

part of the railroad land grants. Other lands

surrounding what became the Lindsay Ranch were

homesteaded by various settlers in the 1880s and 1890s.

Between the late 1880s and 1916, the Jones family, one

of the original homesteaders in the area, had acquired

the area that would become the Lindsay Ranch. During

this time, many of the original homesteads were being

consolidated into larger parcels to provide pasture for

cattle (Dames and Moore 1991). 

In 1916, almost 700 acres of land in the area were sold to

the Ebertharter family, who controlled 1,280 acres along

the northern portion of the current Rocky Flats site. In

1941, a 640-acre ranch property was sold to George and

Susan Lindsay. The Lindsays resided in Denver and

raised cattle on the ranch at Rocky Flats. The Lindsays

owned the ranch property at Rocky Flats and a 320-acre

ranch parcel at the west end of Leyden Gulch, south of

An apple orchard is the only remaining visible remnant of .the stage coach stop along Woman Creek.

© RFETS
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 51

Rocky Flats. The barn was constructed in the mid1940s, followed by the construction of the house in 1949.

The house was occupied by a caretaker until the

property was condemned by the U.S. Atomic Energy

Commission for the development of the Rocky Flats

plant in 1951.

Maintenance of the ranch structures ceased in 1952.

During the operation of the Rocky Flats plant, security

personnel informally used both the house and barn for

target practice. The Lindsay Ranch area now consists of

a large barn, a collapsed shed, corral, livestock chute,

and a frame house. A blizzard in March 2003 dumped

over 3 feet of snow in the area, collapsing the east and

west wings of the barn. During the fall of 2003, the

Service, in partnership with DOE stabilized the barn to

prevent further damage to the structure (Norman 2003).

The two wings were essentially rebuilt. Part of the barn

roof was repaired. Portions of the concrete foundations

were replaced. The windows and doors were boarded to

protect the structure from wind and moisture. 

The house is in a dilapidated condition, with holes in the

roof and walls and an unstable floor, and has not been

maintained or stabilized since it was last used in 1951.

Cold War Era

The Rocky Flats site was one of the 13 nuclear weapons

production facilities in the United States during the Cold

War. Weapons production ended in 1989. The DOE

completed an inventory of all buildings on the site and

determined 64 facilities within the Industrial Area are

very important to regional, national and international

history for their role during the Cold War era. The State

Historic Preservation Office has determined that these 64

facilities are eligible for listing in the National Register of

Historic Places as a historic district (DOE 1997). All of

these facilities will be removed prior to site closure and

establishment of the Refuge.

3.8. INFRASTRUCTURE, EASEMENTS, 

AND UTILITIES

TRANSPORTATION

The Rocky Flats site is surrounded on all sides by state

highways or a major thoroughfare. Colorado Highway 128

defines most of the site’s northern boundary, while

Highway 93 runs parallel to the western boundary about

1⁄4 mile to the west. Less than 1 mile to the south,

Highway 72 runs parallel to the site’s southern boundary.

Indiana Street defines the site’s eastern boundary.

Current access to the site is from Highway 93 or Indiana

Street. The existing access road leading into Rocky Flats

Environmental Technology Site east from Highway 93

carries approximately 2,700 vehicles per day (David Evans

2003). However, traffic on the existing access road will be

greatly reduced following cleanup and closure of the site

by DOE.

Highway 93

Colorado State Highway 93 west of Rocky Flats is

relatively straight and flat with adequate sight distance in

the vicinity of the existing access road. The Rocky Flats

access road intersects Highway 93 at a signalized

During the fall of 2003, the Service, in partnership with

DOE, stabilized the barn and rebuilt the two wings. 

© Mauro

Table 6. Daily and Peak Hour Traffic Volume Summary

Roadway Segment

SH 93 – West of Rocky Flats

SH 128 – East of SH 93

Indiana Street – East of Rocky Flats

2002 AADT†

19,040

4,510

–

2003

Weekday Count

22,110

5,170

5,580

2021

Estimated AADT

28,500

6,700

8,100

† Traffic volumes from CDOT website (CDOT 2003). 

AADT = Annual Average Daily Traffic.

Source: David Evans and Associates, Inc. (2003).
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 53

intersection about 1.5 miles north of Highway 72. The

section of Highway 93 at the access road has two through

travel lanes with a southbound left turn lane and

northbound right turn lane, as well as northbound and

southbound acceleration lanes at the intersection. This

segment of Highway 93 is categorized as an Expressway

(Category E-X) in the CDOT State Highway Access

Category Assignment Schedule (CDOT 2001), which

defines the requirements for access locations, operation

and design criteria along roadways on the state highway

system. The speed limit along Highway 93 approaching

the signal is 45 mph. Highway 93 carries about 22,100

vehicles per day (measured north of the west access road)

(David Evans 2003). This volume is projected to increase

during the life of the CCP (Table 6). 

The Highway 93 and Highway 72 intersection southwest

of the site is signalized. The Highway 93 and Highway 128

intersection northwest of the site is also signalized.

Highway 128

Colorado State Highway 128 north of the site is two lanes

with substantial horizontal and vertical curves between

Highway 93 and McCaslin Boulevard. This segment of

Highway 128 is categorized as a Regional Highway

(Category R-A) in the CDOT State Highway Access

Category Assignment Schedule (CDOT 2001). City of

Boulder and Boulder County Open Space is adjacent to the

roadway on the north side and a signalized intersection is

at McCaslin Boulevard. The speed limit in this segment is

55 mph. Highway 128 west of McCaslin Boulevard carries

about 5,200 vehicles per day (David Evans 2003). This

volume is projected to increase during the life of the CCP

(Table 6).

Indiana Street

Indiana Street east of the site is a straight two-lane

alignment over rolling terrain with little to no shoulder

between Highway 128 and 96th Avenue. The speed limit

in this segment is 50 mph. Indiana Street east of the

project site carries about 5,600 vehicles daily (David

Evans 2003). Traffic volume is projected to increase

during the life of the CCP (Table 6).

This roadway is an arterial maintained by Jefferson

County. The land on the east side of the roadway is City

and County of Broomfield and City of Westminster Open

Space and land owned by the Woman Creek Reservoir

Authority. The Highway 128 and Indiana Street

intersection northeast of the site is signalized. The

existing Rocky Flats Environmental Technology Site has a

gated access at a signalized intersection on Indiana Street

about 1.5 miles north of 96th Avenue. The Indiana Street

and 96th Avenue intersection southeast of the site is also

signalized.

Internal Roads

The Rocky Flats site currently has many roads, fences

and utilities that serve its pre-closure functions. Outside

of the Industrial Area, which currently contains a

network of paved streets, most of the site is accessed by a

network of graded gravel roads and minor two-track

roads. In addition, existing mineral rights and water

rights on site are owned by outside entities. Existing

infrastructure, utility easements and mining permits are

shown on Figure 14.

UTILITIES

The utility infrastructure currently serving the site,

including electric and sewer lines, will be removed or

remediated in place prior to closure. According to the

Refuge Act (Appendix A), existing, privately owned utility

easements across the site will remain in place and the

owners of those easements will have the right to continue

to access them.

Natural Gas Easements

Two natural gas easements are currently on the site, a

north-south easement and an east-west easement. The

north-south easement runs through the eastern portion of

the site. The east-west easement runs along the southern

edge of the Industrial Area, extending between the east

and west access gates (Figure 14). In an area east and

south of the Industrial Area, the title to portions of both

natural gas easements is unclear (Schiesswohl 2003). 

Electrical Line Easements

A 230-kV electrical line follows an easement through the

southern and eastern portions of the site. The line runs in

a north-south orientation between the north boundary and

East entrance road to Rocky Flats.

© USFWS
Chapter 3: Refuge and Resource Descriptions

54 Rocky Flats National Wildlife Refuge 

the proximity of South Woman Creek, where it then runs

southwesterly toward the southern boundary of Rocky

Flats. A second electrical line easement runs from the

proximity of the C-2 pond to the east gate along Indiana

Street. 

Two parallel 115-kV electrical lines follow easements from

the northeast corner of Rocky Flats toward the Industrial

Area. These lines were constructed primarily to serve the

Industrial Area and will be removed and easements

abandoned prior to site closure. Another electrical line

easement follows the west access road from Highway 93 to

the Industrial Area. This electrical line has been removed

and the easement will be abandoned (the title to this

easement is unclear). These easements are shown on

Figure 14. An electrical line with no easement follows the

west side of Indiana Street, within the Rocky Flats

boundary. 

Other Utilities

A fiber optic line with an easement runs from the NWTC

in the northwest corner of the site, across the Rock Creek

drainage, to the Industrial Area. The future of this line and

easement is uncertain. In addition to the electrical line

along the west side of Indiana Street, a telephone and fiber

optic line also follows the Indiana right of way. These utility

lines do not have easements and may be within the Rocky

Flats site (instead of the Indiana right of way) (Schiesswohl

2003).

MINERAL RIGHTS

A substantial portion of the mineral estate (subsurface

mineral rights) associated with lands at Rocky Flats is

privately owned. The Service believes that the exercise of

these existing privately owned mineral rights, particularly

surface mining of gravel and other aggregate material, at

Rocky Flats will have an adverse impact on the

management of the Refuge. The Service does not believe

it can manage the Refuge for meeting the purposes of

section 3177(e)(2) of the Refuge Act if certain mineral

rights are exercised. Accordingly, the Service will not accept

transfer of administrative jurisdiction from DOE for lands

subject to the mining of gravel and other aggregate material

at Rocky Flats until the United States owns the mineral

rights of the land to be transferred to the Service, or until

the mined lands have been reclaimed to a mixed prairie

grassland community. 

Three permitted mining areas currently exist on Rocky

Flats (Figure 14):

• Bluestone Sand and Gravel mine and Bluestone

expansion – 425 acres

• Lakewood Brick and Tile – 80 acres

• Church Ranch Rocky Flats Pit – 94 acres

LaFarge, Inc. (formerly Western Aggregates) operates the

Bluestone sand and gravel quarry in the northwestern

corner of the site. While the permit area includes 425

acres of land, about 300 acres are designated for habitat

preservation, or non-mining setback, easements and buffer

areas (Jefferson County 2002). The Bluestone permit

allows expansion of the mine into the northern portion of

the Rock Creek drainage, near the NWTC (Figure 14).

Most of the Rock Creek drainage is included in a habitat

preservation area. 

Lakewood Brick and Tile operates an 80-acre

clay mining area immediately north of the west

access road. 

In 2004, Church Ranch received a permit for gravel

extraction from the Rocky Flats Pit, located east of the

Lakewood Brick and Tile operation on the north side of

the west access road. As directed by the Colorado

Division of Minerals and Geology in the mining permit,

the Church Ranch mining plan stipulates that it will not

Many internal roads will be revegetated.

© Shapins Associates

Clay mining along the Refuge’s western boundary.

© USFWS
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 55

expose groundwater. Mining activities will stay a

minimum of 2 feet above groundwater (CDMG 2004;

Church Ranch 2004). 

WATER RIGHTS

As discussed in the Water Resources section, the

current water supply to the Rocky Flats site will be

terminated following the cleanup and closure of the

existing facilities. The U.S. Government does not own

water rights on the Rocky Flats site. However, two

outside entities do own water rights. The Smart Ditch

and Irrigation Company owns water rights through

the Smart Ditch from Rocky Flats Lake (west of the

site) to the D-2 Pond in the southeast corner. The City

and County of Broomfield owns water rights in the

Upper Church Ditch and the McKay Ditch, which

convey water across Rocky Flats to the east and

northeast. Other water rights on the site include the

Mower Ditch and the Kinnear Ditch (Advanced

Sciences 1991). A new water supply to serve the

Rocky Flats NWR is not planned. 

3.9. SURROUNDING LAND USE

The Rocky Flats site is at the intersection of Jefferson,

Boulder and Broomfield counties. The site is surrounded

by open space to the north, east and west and urban

development to the northeast and southeast (Figure 15).

Other nearby land uses include mining operations, wind

energy research, and water collection and storage

facilities.

MUNICIPALITIES

Four principal cities and towns, Arvada, Westminster,

Broomfield and Superior, are located within close

proximity of Rocky Flats. The general land uses of those

portions of these municipalities located near the site are

described below.

The City of Arvada is located southeast of Rocky Flats.

While most of Arvada’s residential and commercial

development is over 1 mile from Rocky Flats, the City’s

incorporated boundary directly abuts the site. A large

area immediately south of Rocky Flats and east of

Highway 93 has been annexed by the City and is planned

for residential and mixed development. This area, known

as the Vauxmont property, is currently vacant and used

for livestock grazing.

North of Arvada, the City of Westminster is located

directly east of Rocky Flats. However, most of the

western portions of Westminster’s incorporated area

consist of open space. Residential land uses begin about

1.5 miles east of Rocky Flats.

The City and County of Broomfield is located immediately

east and northeast of Rocky Flats. The area to the east is

dominated by open space associated with Great Western

Reservoir and undeveloped land. Other portions of this

area are planned for development supporting office

complexes. An existing office complex is located about 1

mile northeast of Rocky Flats on the north side of

Highway 128.

The Town of Superior is north and northeast of Rocky

Flats’ northeastern corner. Existing residential land uses

are about 1⁄4 mile north of Rocky Flats and future

residential developments are proposed for the area.

Superior’s town center is located about 2 miles north of

the Rocky Flats boundary.

WOMAN CREEK RESERVOIR AUTHORITY

The Woman Creek Reservoir Authority is a separate unit

of government composed of the cities of Westminster,

Thornton and Northglenn. The Authority constructed the

Woman Creek Reservoir in 1996 to prevent the flow of

surface water from Rocky Flats into Standley Lake, a

Downy paintbrush.

© Nelson, RFETS
Chapter 3: Refuge and Resource Descriptions

56 Rocky Flats National Wildlife Refuge 

drinking water source for several communities (CDPHE

2003a). The Woman Creek Reservoir Authority owns the

reservoir and some of the land surrounding the reservoir.

OPEN SPACE

The Rocky Flats site is surrounded on three sides by

designated open space. These open space lands are owned

and managed by seven different jurisdictions and are

described in detail in Section 3.10.

OTHER NEARBY LAND USES

The Colorado State Land Board manages state land in

Section 16 immediately southwest of Rocky Flats.

Portions of Section 16 have been mined for clay and

aggregates and most of the land is leased for grazing

livestock. 

The DOE’s National Renewable Energy Laboratory

operates the NWTC immediately northwest of Rocky

Flats. This facility is used for research on powergenerating wind turbines. 

Denver Water owns a large tract of land about 1 mile to

the southwest of Rocky Flats along the west side of

Highway 93 from Highway 72 south to Ralston Reservoir.

While portions of this land are used for water collection

and distribution facilities, most of it is undeveloped. This

property includes a potential reservoir site in Leyden

Gulch (Bassett 2002).

Two companies, TXI and LaFarge, operate gravel

mining and processing facilities on two separate but

contiguous sites in the northwest corner of Rocky Flats

site and on adjacent privately owned land. The mining

facilities consist of surface excavations, material

conveyors, rail lines and processing facilities (DOENREL 2002).

Jefferson County Airport is located about 2 miles east of

Rocky Flats. Airport runways are aligned in a

northeast/southwest configuration. Aircraft takeoff and

landing patterns currently do not pass directly over the

Rocky Flats site (DOE-NREL 2002).

3.10. OPEN SPACE, RECREATION AND TRAILS

Rocky Flats is surrounded on three sides by designated

open space. While some of these open space parcels

restrict public use, others provide a network of

recreational trails that are connected to the surrounding

communities (Figures 15 and 16).

CITY OF BOULDER OPEN SPACE AND MOUNTAIN PARKS

The City of Boulder Open Space and Mountain Parks

(BOSMP) owns and manages several large open space

parcels near the northern and western edges of Rocky

Flats. BOSMP lands along the northern edge of Rocky

Flats extend from near the middle of Rocky Flats to the

west along the Boulder/Jefferson county line for over 4

miles to the top of Eldorado Mountain. These lands are

collectively referred to as South Boulder Open Space.

Within Jefferson County, BOSMP also owns the Jewell

Mountain and Van Fleet properties to the west of Rocky

Flats between Highway 93 and Coal Creek. 

BOSMP lands offer a network of soft-surface trails

available for hiking, mountain biking and equestrian use.

The Flatirons Vista and Greenbelt Plateau trailheads are

located about 1 mile from Rocky Flats to the northwest

near the Highway 93/128 intersection.

BOSMP is working with several other organizations to

protect and restore the Coal Creek riparian area that runs

through their properties near Rocky Flats. Restoration

activities include fencing to control livestock, stream

channel restoration, wetland restoration and monitoring.

Small mammal trapping along Coal Creek has revealed

several occurrences of Preble’s meadow jumping mouse

(BOSMP 2002).

BOULDER COUNTY OPEN SPACE

Boulder County owns several open space parcels on the

north side of Rocky Flats between the Town of Superior

to the east and BOSMP lands to the west. These holdings

include the Lindsay, Zacharias/Thomas and

Carlson/Lastoka properties. Recreational access to

Boulder County Open Space lands to the north and

northeast of Rocky Flats is from the Coalton Trail, which

begins on Highway 128 north of Rocky Flats. The Coalton

Trail provides recreational access (hiking, biking and

equestrian uses) to the County open space lands northeast

of Rocky Flats. The trail connects to the Rock Creek Trail

in the Town of Superior.

JEFFERSON COUNTY OPEN SPACE

Jefferson County owns and manages several parcels to the

west and southwest of Rocky Flats. The Ranson-Edwards

property immediately west of Rocky Flats extends from

Coal Creek to the west. Coal Creek Canyon Open Space is

located along the south side of Highway 72 about 2 miles

west of Rocky Flats. Jefferson County also owns several

conservation easements in this area. White Ranch Open
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 59

Space is located about 3 miles to the southwest of Rocky

Flats.

The 2,807-acre Coal Creek Canyon Park currently has no

developed trails or facilities. Due to uncertainty

surrounding the future management of surrounding

publicly owned properties, including Rocky Flats and

Denver Water properties, Coal Creek’s Management Plan

recommends postponing trail and facility development for

5 to 7 years (JCOS 2001).

CITY OF ARVADA OPEN SPACE

The City of Arvada owns several open space parcels about

2 miles south of Rocky Flats. These parcels are around

Arvada Reservoir, along Leyden Gulch, and in the area

between the two. A network of paved and unpaved trails

runs throughout the City of Arvada, including the

unpaved Leyden Gulch trail located about 1.5 miles south

of Rocky Flats.

The City has identified additional trail corridors south of

the Rocky Flats site that would provide potential linkages

between Arvada and the Refuge (City of Arvada 2001).

Proposed trails include the following:

• Leyden Gulch Trail – This extension of an

existing trail will cross Highway 93, providing

access to Jefferson County open space. It will

be open to hiking, biking and equestrian users.

• Big Dry Creek – The trail will follow the Big

Dry Creek from Standley Lake to Highway 93

and will border the Refuge’s southern

boundary. A proposed trailhead for the Big

Dry Creek trail will be 1

/8mile south of the

Refuge’s boundary. The hiking and biking trail

could also link the Refuge to the proposed

Vauxmont Park. 

• Barbara Gulch Trail – This trail will extend

from the Highway 72/93 intersection to the

City of Arvada. The trailhead at the

intersection will be an important hub in an

alternative transportation route (e.g., bike

commuters) along Highway 93.

• Jeffco Trail – The City’s master plan also

identifies a proposed Jeffco trail along

Church Ditch which runs north-south

between the Refuge and Standley Lake.

CITY OF WESTMINSTER OPEN SPACE

The City of Westminster has several open space

properties to the east and southeast of Rocky Flats.

These properties include the Colorado Hills Open

Space and Standley Lake Regional Park. Colorado

Hills includes a soft-surface trail between Mower

Reservoir and adjacent residential areas. Standley

Lake is a regional destination for boating, swimming

and picnicking. This park is also a focal point for

Arvada and Westminster’s paved greenway trail

systems. The city’s soft surface Walnut Creek Trail

terminates less than 2 miles from Rocky Flats’ eastern

boundary and is open to hiking and biking. The trail

could provide a potential link between the Refuge,

surrounding communities and the Westminster trail

system.

CITY AND COUNTY OF BROOMFIELD OPEN SPACE

Directly east of Rocky Flats, Broomfield owns the Great

Western Open Space lands surrounding its Great Western

Reservoir. This area consists mainly of former grazed or

cultivated fields. The City and County of Broomfield

considers Great Western Open Space to be a highly

suitable receiving site for prairie dog relocation (City and

County of Broomfield 2001). The establishment of a large The black-tailed jack rabbit is found on the Refuge.

© USFWS
Chapter 3: Refuge and Resource Descriptions

60 Rocky Flats National Wildlife Refuge 

prairie dog town at Great Western Reservoir Open Space

would likely attract a greater number of raptors and other

predators to the area and may encourage the expansion of

prairie dogs in the eastern portions of the Refuge.

TOWN OF SUPERIOR OPEN SPACE

Superior’s open space is located across Highway 128 at

the northeast corner of Rocky Flats, on the east side of

McCaslin Boulevard. A network of paved trails throughout

Superior’s residential neighborhoods connects to the Rock

Creek Trail, which continues to the northeast into

Broomfield (Superior 2001).

3.11. VISUAL RESOURCES

Visual resources at Rocky Flats can be placed under

three general categories: views of the Rocky Flats area

from surrounding communities, views from Rocky

Flats to surrounding landmarks, and internal views.

Disturbed areas at Rocky Flats are also a component

of its current visual character.

VIEWS FROM SURROUNDING AREAS

Situated on a high, sloping pediment, the Rocky Flats site

lies at the base of the Front Range of the Rocky

Mountains. This area is commonly referred to as the

Front Range mountain backdrop and consists of various

ridges and peaks including South Boulder Peak, Eldorado

Mountain, Crescent Peak and the Ralston Buttes. Beyond

the mountain backdrop are the Indian Peaks, which are

intermittently visible from Rocky Flats and surrounding

communities.

The Rocky Flats area, including the Refuge and

surrounding open space lands, defines the northwestern

boundary of the Denver metropolitan area, where urban

and suburban development gives way to open grasslands

that slope up into the craggy forests of the mountain

backdrop. Views to Rocky Flats capture a range of

landscape types as the grasslands give way to the

ponderosa draped foothills and on to the towering Rocky

Mountains. This view can be appreciated from many areas

throughout the Denver metropolitan region. 

VIEWS FROM ROCKY FLATS

Several notable views from the Refuge characterize the

site’s visual quality. These views, both internal and

distant, are enjoyed from some of the high points along

the pediment in the western and central portions of the

Refuge. The view of the Rock Creek drainage and Lindsay

Ranch from the east is one of the most striking views from

the Refuge. 

While Rock Creek offers topographical relief and

vegetative variety, the Lindsay Ranch structures reveal

the site’s history. Beyond these immediate features, the

high peaks along the Continental Divide are visible

through Eldorado Canyon. From the upper Walnut Creek

area looking east, the mixed grassland prairie and

riparian areas in the eastern portions of the Refuge are

backed by Great Western Reservoir and the communities

and open plains beyond. Several high points in the

southern portion of the Refuge provide distant views to

the southeast of Standley Lake and the downtown Denver

skyline. 

The Front Range mountain backdrop is a visual resource at the Refuge.

© Mauro
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 61

INTERNAL VIEWS

Internal views at Rocky Flats are generally characterized

by the open grassland landscape. While the majority of

the site is composed of large expanses of uninterrupted

grassland, distinct vegetation along drainages (i.e.,

cottonwoods and upland shrubs) and varied topography

present additional visual resources. Numerous drainages

and gullies slope steeply to the east where the flat

pediment top gives way to more rolling grasslands. This

terrain provides numerous opportunities for scenic

overlooks with commanding views as well as secluded

pockets with intimate views of the Refuge landscape.

DISTURBED AREAS

Visual resources at Rocky Flats are affected by facilities

associated with mining and former weapons production on

the site. Currently over 70 miles of maintenance and

access roads occur on the Rocky Flats site (including

Refuge land and area to be retained by DOE). While these

roads are generally not visible from surrounding areas,

they interrupt many of the internal views at Rocky Flats.

The buildings and facilities within the Industrial Area are

visible throughout the site and are a visual landmark from

surrounding areas. Prior to the establishment of the

Refuge, these facilities will be removed and much of the

current Industrial Area will consist of restored

grasslands. While the industrial nature of this area will

change, it will continue to compromise internal views and

will be a visual reminder of the former facilities for several

years. Over the long term, as grassland restoration begins

to take form, DOE envisions a visually “seamless” division

between the Refuge and the former industrial site that

will be retained by DOE. 

3.12. NOISE

Existing noise levels vary widely across the Refuge. Noise

levels on the north, west and east perimeter are affected

by traffic on the highways adjacent to these locations.

Because traffic volumes are higher on Highway 93, noise

levels are higher on the western perimeter than at other

locations. Noise levels are lower on the southern perimeter

because Highway 72 is farther from the site boundary.

Wind generators at the NWTC also generate noise. While

the site is undergoing cleanup and building demolition,

construction noise near the Industrial Area is considerably

louder than ambient conditions. Noise levels vary with the

type of cleanup activity. Rocky Flats is typically a very

windy location and wind noise contributes to the overall

ambient noise levels.

Noise levels decrease away from area highways, site

cleanup, and NWTC wind generators. After cleanup,

noise levels in the center of the Refuge will be very low

and the Refuge will provide opportunities for solitude.

3.13. AIR QUALITY

Rocky Flats is located within the boundary of the Denver

Metropolitan Area for air quality planning purposes. For

many years, the Denver metropolitan area has

experienced carbon monoxide, ozone, and particulate

matter air pollution as well as visibility problems. These

conditions have recently improved, however, and the

Denver area is now in attainment of most of EPA’s healthbased standards for air quality with the exception of ozone

(EPA 2002). Ozone levels in the summer of 2003 violated

standards (CDPHE 2003). Regulatory requirements may

control the timing of certain natural resources

management activities, such as prescribed burning, which

requires a permit from the state.

Air quality is monitored at five air monitoring stations

operated by the CDPHE. Two of these stations are located

just off-site at the northeast and southeast site boundary

along Indiana Street, downwind of Rocky Flats. All

criteria air pollutants are below state standards. It has not

been determined whether the air monitoring stations will

be removed following cleanup of the site.

3.14. SOCIOECONOMICS

POPULATION AND DEMOGRAPHICS

The population in Jefferson County grew from 438,430 in

1990 to 527,056 in 2000 (U.S. Census Bureau 2002), an

average annual increase of about 1.8%. Jefferson County

population is expected to increase about 0.75% annually

from 2000 to 2015, while the state population is expected

to increase by 1.7% annually (Colorado Department of

Local Affairs 2002). 

Rocky Flats is located in Jefferson County’s North Plains

Community Planning Area, which also includes portions of

Westminster, Arvada, Golden and unincorporated areas.

Within this planning area, the population grew from 8,453

in 1990 to 10,194 in 2000, an average annual increase of

about 2% (Jefferson County 2002). About 95% of the North

Plains population consider themselves to be white

(compared to 83% state wide), while about 5% consider

themselves to be Hispanic or Latino in origin (Jefferson

County 2002).

EMPLOYMENT

The average unemployment rate for Jefferson County

in 2001 was 3%, while the state average was 3.72%
Chapter 3: Refuge and Resource Descriptions

62 Rocky Flats National Wildlife Refuge 

(Colorado Department of Local Affairs 2002). In 2000,

the services sector employed 79,317 workers while the

retail trade sector employed 62,838 and the

government sector employed 51,762 (Colorado

Department of Local Affairs 2002).

INCOME

In 2000, per capita personal income was $36,442, a

5.6% annual increase since 1990. Total personal income

in Jefferson County was $19.3 billion in 2000, up from

about $9.4 billion in 1990, reflecting an average annual

growth rate of about 7.5% (Bureau of Economic

Analysis 2002). The largest sources of work-related

personal earnings by industry were services (16.1%),

government (8.3%), and manufacturing (7.9%). Retail

trade accounted for about 3% of the total personal

income in 2000. Transfer payments, dividends, interest

and rent accounted for 22% of personal income in 2000

(Bureau of Economic Analysis 2002). 

3.15. REFERENCES

Advanced Sciences, Inc. 1991. Surface-Water and

Ground-Water Rights Study in the Vicinity of

the Rocky Flats Plan. Prepared for EG&G

Rocky Flats, Inc. Lakewood, Colorado.

Bassett, Marie. 2002. Denver Water Department.

Personal Communication with Bill Mangle,

ERO Resources, September 4, 2002.

Brennan, Mark. 2003. Boulder County Parks and

Open Space Department. Personal

Communication with Ron Beane, ERO

Resources, April 16, 2003.

Bureau of Economic Analysis. 2002. Regional Accounts

Data: Local Area Personal Income.

http://www.bea.doc.gov/regional/reis/action.cfm

Church Ranch. 2004. Technical Revision to Rocky Flats

Pit, Permit number M-1987-113.

City and County of Broomfield. 2001. Final Draft

Policies for Prairie Dog Conservation and

Management.

City of Arvada. 2001. City of Arvada Parks, Trails

and Open Space Plan. Prepared by EDAW.

City of Boulder Open Space and Mountain Parks

Department. 2002. Rocky Flats EIS Scoping

Response: Sharp-tailed Grouse

Reintroduction.

Clippinger, N.W. 1989. Habitat suitability index

models: black tailed prairie dog. Biological

Report 82 (10.156): 1-21. U.S. Fish and Wildlife

Research and Development. Washington, D.C.

Colorado Department of Local Affairs. 2002.

Colorado Economic and Demographic

Information System.

http://www.dola.state.co.us/is/cedishom.htm

Colorado Department of Public Health and

Environment. 2003a. Contaminants Released to

Surface Water from Rocky Flats. Technical

Topic Papers: Rocky Flats Historical Public

Exposures Studies.

http://www.cdphe.state.co.us/rf/contamin.htm 

Colorado Department of Public Health and

Environment. 2003b. Colorado Air Quality

Control Commission: Report to the Public,

2002-2003.

Colorado Department of Transportation. 2001.

Colorado Department of Transportation State

Highway Access Category Assignment

Schedule.

Colorado Department of Transportation. 2003. The

Colorado Department of Transportation

Traffic Information Page.

http//www.dot.state.co.us/App_DTD_DataAcc

ess/Traffic/.

Colorado Division of Minerals and Geology

(CDMG). 2004. Permit issuance, Rocky Flats

Pit, Permit number M-1987-113, with rider.

January 13, 2004.

Colorado Division of Wildlife. 1992. Plains Sharptailed Grouse Recovery Plan.

Colorado Division of Wildlife. 2001. Colorado

Vertebrate Ranking System (COVERS)

Database.

ftp://www.NDIS.NREL.colostate.edu/. 

Colorado Division of Wildlife. 2003. Grassland

Species Conservation Plan. Colorado Division

of Wildlife.

Dames and Moore. 1991. Cultural Resources Class

III Survey of the Department of Energy Rocky

Flats Plant, Northern Jefferson and Boulder

Counties, Colorado. Prepared for EG&G Rocky

Flats.
Chapter 3: Refuge and Resource Descriptions

Final Comprehensive Conservation Plan 63

David Evans and Associates, Inc. 2003. Letter

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