Geochemical Baselines of Stream and Spring 

Waters From Areas Underlain by Permian and 

Pennsylvanian Rocks, Including Evaporites, and 

Potential Environmental Damage in the Eagle 

Valley, Colorado 

by William R. Miller1 

Open-File Report 01-362 

2001 

This report is preliminary and has not been reviewed for conformity with the U.S. Geological 

Survey editorial standards and stratigraphic nomenclature. Any use of trade product or firm 

names is for descriptive purposes only and does not imply endorsement by the U.S. Government. 

U.S. DEPARTMENT OF THE INTERIOR 

U.S. GEOLOGICAL SURVEY 

1

Denver, Colorado 
Introduction 

When precipitation, as rain and snow, falls within a watershed, water comes into contact 

with rock minerals and chemical weathering is initiated. These processes release elements to the 

natural waters of a watershed. Therefore the chemical composition of natural waters that evolve 

within a watershed, in the absence anthropogenic input, is determined mostly by the chemical 

composition of rocks within the basin. Other factors such as rates of mechanical erosion, grain 

size and crystallinity of the rock minerals, amount and distribution of precipitation, temperature, 

type and amount of vegetation, and biota activity influence mainly the rates of the water-rock 

reactions, but the chemical composition of the rocks is the fundamental factor which determines 

the type of waters which evolve within a headwater watershed (Miller, 1999). This natural 

baseline geochemistry of waters of a watershed can be modified by input from anthropogenic 

processes which are always superimposed on the background geochemistry. The distribution of 

water available in streams and springs in these headwater watersheds is uneven throughout the 

year in western Colorado with high flows during the spring runoff and after summer 

thunderstorms. In the winter, water available in streams and springs reaches a minimum when 

element concentrations are high but mass flux is low. At this time, runoff is fed mainly by the 

recession of the groundwater reservoir. Geochemical baselines, at a particular point in time, can 

be determined for stream and spring waters in these headwater watersheds, and may approximate 

the background geochemistry. Because water geochemistry is sensitive to changes in the 

environment, by monitoring water geochemistry in these watersheds and comparing the results to 

the earlier geochemical baseline data, changes within the watershed can be detected. 

The purpose of this study is to determine the baseline range of species and other 

geochemical parameters in order to characterize the baseline geochemistry of stream and spring 

waters evolving within headwater watersheds underlain by Permian and Pennsylvanian rocks 

which occur in western Colorado and often contain highly soluble evaporite minerals. Processes 

responsible for the control and mobility of species in the natural waters were also investigated as 

well as potential environmental damage associated with development of golf courses, homes, and 

1
ski areas on the Evaporite Facies rocks in Eagle Valley. 

Study Area 

The study areas occur within western Colorado (fig. 1) in the Southern Rocky Mountain 

physiographic province (Hunt, 1974). The mountain ranges and intermountain basins generally 

trend north-northwest. Dendritic drainage patterns are well developed and most of the area is of 

moderate to high relief. Several peaks are above 14,000 feet and the lowest point is around 

6,500 feet along the Arkansas River. Annual precipitation ranges from as little as 10 inches near 

Antereo Reservoir in South Park to more than 40 inches in the higher Flat Tops area (Colorado 

Climate Center, 1984). Snow-melt runoff usually occurs from April through July and peaks in 

May through June (Apodaca and others, 1996). 

Because of the large differences in altitude, the climate in the study area varies from coolhumid in the higher mountains to semi-arid in the lower elevations. The natural vegetation in the 

study area is strongly zoned by altitude. The vegetation in the subalpine zone is dominated by 

spruce and fir, the montane zone by pine and Douglas fir, which can alternate with juniperpinyon woodland, and mountain mahogany - scrub oak. Unforested mountain parks dominated 

by grasses and sometimes sagebrush and other shrubs are also present (U.S. Dept. of Agriculture, 

1972). 

Geological History of the Permian and Pennsylvanian Rocks 

Permian and Pennsylvanian rocks in Colorado were formed during a series of continental 

collisions that resulted in deformation and uplift. The Ancestral Rocky Mountains formed 

around 300 mya probably as the result of the collision of North America with South AmericaAfrica along the southern margin of North America (Curtis, 1958). Tectonic activities consisted 

of block-fault mountain uplifts and subsiding basins between the uplifts. The Ancestral Rocky 

Mountains formed along two belts. The eastern belt is known as the ancestral Front Range uplift 

and the western belt as the Uncompahgre uplift. During the early stages of tectonic activities, 

2
1 

3 

2 

4 

5 

COLORADO 

Figure 1. Location of study areas: 1) Redcliff area; 2) Flat Tops Area 

3) Eagle Valley area; 4) South Park area; 5) Sangre de 

Cristo area. 

3
shallow seas invaded the basins and deposited marine sediments from the adjoining mountain 

uplifts. One of the large basins, the central Colorado trough, extended from northwest Colorado 

to south-central Colorado and contains between 10,000 to 20,000 feet of Permian and 

Pennsylvanian rocks of both marine and nonmarine origin (DeVoto, 1972). The earliest basindeposited sediments of Pennsylvanian age in the central Colorado trough are marine-transitional 

black shales and sandstone of the Belden Formation. The Minturn Formation and the younger 

Maroon Formation overlies the Belden Formation and consist of marine and nonmarine 

sediments accumulated adjacent to the basin margins but pass into evaporite and clastic deposits 

of the Eagle Valley Evaporite in the center of the basin (Mallory,1971). The Eagle Valley 

Evaporite between the towns of Avon and Gypsum, consists of a thick sequence of interbedded 

gypsum, anhydrite, halite, black shale and siltstone formed by evaporation of a narrow seaway. 

Along the flanks of the Ancestral Rockies, sediments derived from the eroding mountain 

uplifts accumulated as valley fill and alluvial fans consisting of arkosic gravels and sands and 

conglomerates, predominately red in color (redbeds). In south-central Colorado, the Sangre de 

Cristo Formation of sandstones, conglomerates, and shales was deposited on mudflats with 

stream channels. The erosion of the Ancestral Rockies and the deposition of sediments in the 

basins continued into Permian time. By middle Permian time, terrestrial sedimentation had 

decreased and shallow seas invaded the region. 

Evaporite minerals, particularly gypsum, are known to occur in the Pennsylvanian and 

Permian rocks throughout central Colorado. Gypsum is mined from the central Colorado trough 

near the town of Gypsum and along the Arkansas River below Salida, Colorado. 

Methods 

Generally small streams were sampled, usually with a watershed area of around several 

square miles, although some watersheds are larger. Springs within the watershed were also 

sampled. Waters were collected from five rock groups of Permian and Pennsylvanian age in 

western Colorado. The five rock groups are: 1) Pennsylvanian Minturn and Belden Formations 

in the Redcliff area, 2) Pennsylvanian Minturn and Belden Formations in the Flat Tops area; 3) 

4
Pennsylvanian Minturn and Belden Formations in the Sangre de Cristo Range; 4) Permian and 

Pennsylvanian Sangre de Cristo Formation in the Sangre de Cristo Range; and 5) Pennsylvanian 

Eagle Valley Formation, Evaporitic Facies in Eagle Valley and Evaporitic Facies of Minturn and 

Belden Formations in South Park (Tweto, 1979). The last group is from two areas but because 

all contain evaporite facies minerals, the two areas are combined and will be referred to as 

Evaporite Facies of Eagle Valley and South Park. Samples of water were collected from 36 

streams and 9 spring sites from July 18 to August 24, 2000. The waters were collected after peak 

runoff had occurred but prior to the streams reaching base flow or in some cases, drying up 

completely. Generally, during the time of sampling, the weather was stable and no precipitation 

occurred. Waters from each of the study areas were usually collected within one or two days. 

Waters from areas of lower elevations were collected earlier in the season than the higher areas. 

During the time of sampling, the weather was stable and no precipitation occurred. Samples 

were collected by width and depth integration (Edwards and Glysson, 1988) or from a point 

source for springs. Temperature, pH, and conductivity were measured at the site. pH was 

measured using an Orion model 250 pH meter with an Orion Ross Sure-Flow electrode. 

Temperature was measured using temperature probe. The conductivity was measured using an 

Orion model 120 conductivity meter. Samples were collected into high-density polyethylene 

bottles. For the dissolved cation analyses, a sample was filtered at the site through a 0.45 :mmembrane filter and acidified with ultrapure reagent-grade Ultrex nitric acid to pH < 2. Another 

sample was filtered but not acidified for anion analyses and an unfiltered, unacidified sample 

was collected for alkalinity measurement. The samples were stored in an ice chest and later in a 

refrigerator and kept cool until analyzed. 

Upon return to the laboratory, alkalinity as HCO3

-

, was determined by titration with 

H2SO4 using Gran’s plot technique (Orion Research, Inc.,1978). Sulfate, chloride, nitrate, and 

fluoride concentrations were determined by ion chromatography (IC) (Fishman and Pyen, 1979). 

Cations were analyzed by inductively coupled plasma - mass spectromentry (ICP-MS) or 

inductively coupled plasma - atomic emission spectrometry (ICP-AES). IC, ICP-AES, and 

alkalinity analyses were performed by Murdock Environmental Laboratory, University of 

Montana, Missoula, The ICP-MS analyses were determined by U.S.G.S. laboratories in Denver 

5
under the direction of Allen Meier. Duplicate water samples, blank samples, and USGS Water 

Resource Division standard reference waters were analyzed with each data set. The chemical 

analyses with date of collection, location, rock type of basin, water type, flow data, and 

comments are shown for all sites in appendix 1. 

Results 

Water samples were collected from small streams or springs of watersheds that were 

mainly within National Forests or Bureau of Land Management lands. The watersheds are 

generally mountainous headwaters and are not impacted by historic mining. The ranges and 

means of species and other parameters were determined for each of the five rock groups. A 

summary of the mean geochemical data of waters collected within each of the groups is shown in 

Table 1. In addition, total dissolved solids (TDS) values were calculated for each site. The TDS 

value represents the total amount of solids (mg/L) remaining when a water sample is evaporated 

to dryness. In calculation from the chemical data, TDS value is the sum of all dissolved 

constituents with bicarbonate converted to equivalent carbonate in the solid phase, which 

assumes that half the bicarbonate is volatilized (Hem, 1992). The TDS value is calculated for the 

waters from each site and is shown in appendix 1. 

Minturn and Belden Formations in the Redcliff Area 

Water samples were collected from seven tributary streams of Turkey Creek and Eagle 

River in the Redcliff area in the White River National Forest (fig. 2). The watersheds are 

underlain by Pennsylvanian Minturn and Belden Formations of sandstone, grit, conglomerate, 

shale, and carbonate rocks (Tweto, 1979). The relief in the area is high and the dominant 

vegetation is subalpine forest (Kuchler, 1965). Annual precipitation ranges from 25 to 40 inches 

(Colorado Climate Center, 1984). The ranges and means of selected species in the waters are 

- shown in Table 2. The sites contain Ca2+- HCO3 type waters with alkaline pH values. Mean pH 

is 8.33 and mean conductivity is 295 :S/cm. Mean total dissolved solids (TDS) is higher than 

6
Table 1. Means of selected chemistry of waters from areas underlain by Permian and 

Pennsylvanian sedimentary rocks. Conductivity in μS/cm, alkalinity 

in mg/L HCO3, TDS, Ca, Mg, Na, K, Si, SO4, Cl, F, and N in 

mg/L, remaining elements in μg/L. 

Variable Minturn and Belden Fms Minturn and Belden Fms 

in the Redcliff Area in the Flat Tops Area 

n 7 8 

pH 8.33 7.82 

Conductivity 295 392 

TDS 240 312 

Ca 41 74 

Mg 11 3.1 

Na 1.6 1.3 

K 0.5 <0.5 

Alkalinity 325 402 

SO4 13 5.4 

Cl <1 <1 

F <0.05 <0.05 

N <0.05 0.22 

Li 2.5 0.6 

Ba 82 45 

Sr 102 127 

Al 3.6 1.6 

Fe 1.3 2.1 

Mn 0.36 1 

Cu <0.5 <0.5 

Zn <0.5 <0.5 

Mo 0.5 0 

Cr <1 3 

Ni 1.2 1.9 

U 1.4 0.8 

7
Table 1 cont. Means of selected chemistry of waters from areas underlain by Permian and 

Pennsylvanian sedimentary rocks. Conductivity in μS/cm, alkalinity in mg/L 

HCO3, TDS, Ca, Mg, Na, K, Si, SO4, Cl, F, and N in mg/L, remaining elements in μg/L. 

Variable Minturn and Belden Fms in Evaporite Facies of Eagle Sangre De Cristo Formation 

the Sangre de Cristo Area Valley and South Park 

n 6 11 11 

pH 8.15 8.09 7.86 

Conductivity 429 685 172 

TDS 334 528 137 

Ca 57 103 24 

Mg 19 21 4 

Na 3.2 7.8 1.9 

K 1.3 1.2 <0.5 

Alkalinity 322 369 179 

SO4 64 155 6.6 

Cl <1 3.6 <1 

F 0.09 0.08 <0.05 

N <0.05 <0.05 <0.05 

Li 1.9 4.0 1.1 

Ba 42 56 66 

Sr 472 1071 121 

Al 2.3 2.7 1.6 

Fe 2.4 10 1.8 

Mn 0.58 4.1 0.23 

Cu 0.5 1 <0.5 

Zn 1.1 1.7 <0.5 

Mo 1.8 1.8 0.3 

Cr 1 1 1.1 

Ni 1.7 3.2 0.7 

U 1.3 1.5 0.35 

8
Gore Creek 

Eagle Creek 

Two Elk Creek 

Minturn 

W illow

C reek 

Lime Creek 

T urkey Creek 

Redcliff 

7 

5 

8 

9 

10 

11 

0 1 Mile 

39 30’ O 

106 15’ O 

Spring Site 

Stream Site 

PmI b

6 

Game Creek 

PmI b Minturn and Belden 

Formations 

Figure 2. Locations of water samples from stream and spring sites in 

the Redcliff area. Geology generalized from Tweto (1979). 

9
Table 2. Summary of selected water chemistry of six streams and one spring in 

watersheds underlain by Pennsylvanian Minturn and Belden Formations in 

the Redcliff area (n=7). Conductivity in mS/cm, alkalinity as mg/L HCO3, 

TDS, Ca, Mg, Na, K, Si, SO4, Cl, F, and N in mg/L, remaining elements 

in mg/L. Values below level of detection were replaced with values of 0.7 

the level of detection. 

Measurement Range Mean 

Minimum Maximum 

Conductivity

TDS

pH

Ca

Mg

Na

K

Si

Alkalinity

SO4

Cl

F

N

Al 

Fe

Mn

Cu

Zn

Mo

Cr

Ni

U

Li

Ba

Sr

187 564 295 

159 426 240 

7.47 8.57 8.33 

29 86 41 

2.5 19 11 

1.3 2.3 1.6 

0.3 1.1 0.5 

2.9 4.7 3.3 

239 393 325 

2.5 119 13 

<1 <1 <1 

<0.05 0.05 <0.05 

<0.05 0.08 <0.05 

2.1 7.4 3.6 

1 2 1 

0.1 4.2 0.4 

<0.5 0.6 <0.5 

<0.5 0.7 <0.5 

0.3 1.3 0.5 

<1 1 <1 

0.8 2.1 1.2 

1 2.1 1.4 

1.3 4.1 2.5 

62 167 82 

53 597 102 

10
average river water (Table 3) with a mean of 240 mg/L. The mean concentrations of Fe, Al, and 

Mn are low compared to average river water with values of 1, 0.4, and 3.6 mg/L, respectively. 

Other trace metals are also low. Mean concentrations of Zn, Cu, Mo, and U are <0.5, <0.5, 0.5, 

and 1.4. Si concentrations are low with a mean of 3.3 mg/L probably because of the rock type 

which contains abundant carbonate minerals as well a gypsum. Alkalinity values are high with a 

mean of 325 mg/L, probably because of the carbonate rocks within the formations. Mean Cl 

content is < 1 mg/L, which is low and reflects the short residence time of the melting snow and 

storm runoff in contact with the rocks and lack of significant evaporation. Because of the high 

alkalinity values, the areas underlain by rocks of the Minturn and Belden Formations in the 

Redcliff area are moderately resistant to introduced acidification, such as a coal-burning power 

plant or acidity from mining wastes. The chemical quality of the waters from watersheds 

underlain by Pennsylvanian Minturn and Belden Formations in this area is good. 

Minturn and Belden Formations in the Flat Tops Area 

Samples of water were collected from three streams and five springs in the Flat Tops area 

in the White River National Forest (fig. 3). The watersheds are underlain by Pennsylvanian 

Belden and Minturn Formations of sandstone, grit, conglomerate, shale, and carbonate rocks 

(Tweto, 1979). Relief is high along the flanks but the upland area containing the springs is 

generally flat lying. The dominant vegetation is subalpine forests with alpine meadows in the 

upland area (Kuchler, 1965). Annual precipitation ranges from 20 to 40 inches (Colorado 

Climate Center, 1984). The ranges and means of selected species in the waters are shown in 

- Table 4. The sites contain Ca2+- HCO3 type waters with alkaline pH values. Mean pH is 7.82 

and mean conductivity is 392 :S/cm. Mean TDS value is higher than average river water (Table 

3) with a mean of 312 mg/L. Mean concentrations of Al, Fe, and Mn are low with means of 1.6, 

2, and 1 :g/l, respectively. Other trace metals are also low. Mean Zn, Cu, Mo, and U are <0.5, 

<0.5 , 0.4, and 0.8 :g/l, respectively. Mean Si concentration is low with a mean of 4.3 mg/L 

probably because of the rock type which contains abundant carbonate minerals as well a gypsum. 

The mean Cl concentration is < 1 mg/L, which is low and reflects the short residence time of the 

11
Table 3. Background of trace metals in freshwater and chemical analyses of mean river water 

Background of trace metals (mg/L) in freshwater 

Element Data after Forstner and Wittmann (1979) 

Al <30 

Fe <30 

Mn <5 

Cu 1.8 

Zn 10 

As 2 

Mo 1 

Pb 0.2 

Sb 0.1 

Cr 0.5 

Ni 0.3 

Li 1 

Se 0.1 

U 0.5 

Chemical analyses (in mg/L) of mean river water 

Element in mg/L Data from Livingstone (1963) 

Ca 15 

Mg 4.1 

Na 6.3 

K 2.3 

Si 6.1 

SO4 11.2 

HCO3 58.4 

Cl 7.8 

Calculated TDS in mg/L 81.5 

12
43 

PPwm 49 

50

Bar HL Park

48 

45 

47 

43 

Triangle Park 

Coulter

Mesa 

Three Forks Ck 

44 

E. Rifle Ck 

Butler Ck 

George

CK 

39 45’ o 

107 37’ 30” o 

0 1 2 Miles 

Stream Site 

Spring Site 

46 

Pmb 

PPwm 

I 

I 

I 

Weber Sandstone and Maroon Formation 

Minturn and Belden Formations 

PPwm 

PPmb 

I 

I 

Figure 3. Locations of water samples from streams and springs in 

the Flat Tops area. Geology generalized from Tweto (1979). 

13
Table 4. Summary of selected water chemistry of three streams and five springs in 

watersheds underlain by Pennsylvanian Minturn and Belden Formations 

in the Flat Tops Area. (n=8). Conductivity in μS/cm, alkalinity as mg/L 

HCO3, TDS, Ca, Mg, Na, K, Si, SO4, Cl, F, and N in mg/L, remaining 

elements in μg/L Values below level of detection were replaced with values 

of 0.7 the level of detection. 

Measurement Range Mean 

Minimum Maximum 

Conductivity

TDS

pH

Ca

Mg

Na

K

Si

Alkalinity

SO4

Cl

F

N

Al 

Fe

Mn

Cu

Zn

Mo

Cr

Ni

U

Li

Ba

Sr

296 633 392 

228 479 312 

7.46 8.31 7.82 

58 108 74 

1.1 18 3.1 

1 2.3 1.3 

<0.5 0.55 <0.5 

3.7 5 4.3 

326 465 402 

1.4 143 5.4 

<1 1.1 <1 

<0.05 0.1 <0.05 

<0.05 0.87 0.22 

0.9 2.2 1.6 

1 14 2 

0.02 13 1 

<0.5 0.6 <0.5 

<0.5 0.6 <0.5 

<0.2 2.2 0.4 

2.1 2.8 2.5 

1.4 2.9 1.9 

0.4 2.4 0.8 

0.3 2.9 0.6 

34 60 45 

53 1040 127 

14
water from melting snow and rain in contact with the rocks and the lack of significant 

evaporation. Alkalinity values are high with a mean 402 mg/L, which indicates good acidneutralizing capacity probably because of abundant carbonate minerals in the rocks. Because of 

the high alkalinity values, the areas underlain by rocks of the Minturn and Belden Formations are 

moderately resistant to introduced acidification. The chemical quality of the waters from 

watersheds underlain by Pennsylvanian Minturn and Belden Formations in this area is good. 

Minturn and Belden Formations in the Sangre de Cristo Range 

Samples of water were collected form six streams in the northern Sangre de Cristo Range 

within the San Isabel and Rio Grande National Forest (figs. 4 and 5). The watersheds are 

underlain by Pennsylvanian Minturn and Belden Formations of shale, siltstone, and sandstone 

with beds of gypsum and marine limestone (Tweto, 1979). Relief is high and the dominant 

vegetation is pine-Douglas fir and spruce-fir forest in the higher areas and juniper-pinyon 

woodland along the lower flanks (Kuchler, 1965). Annual precipitation ranges from 16 to 40 

inches (Colorado Climate Center, 1984). The ranges and means of selected species in the waters 

- are shown in Table 5. The sites contain Ca2+- HCO3 type waters with alkaline pH values. Mean 

pH is 8.15 and mean conductivity is 429 :S/cm. Mean TDS value is higher than average river 

water (Table 3) with a mean of 334 mg/L. The mean concentrations of Al, Fe, and Mn are low 

with means of 2.3, 2, and 0.6 :g/l, respectively. Other trace metal concentrations are low. Mean 

concentrations of Zn, Cu, Mo, and U are 1.1, 0.5 , 1.8, and 1.3 :g/l, respectively. Mean Si 

concentration is 5.2 mg/L probably because of the rock type which contains abundant carbonate 

minerals as well a gypsum. Mean Cl concentration is < 1 mg/L, which is low and reflects the 

short residence time of the water from melting snow and rain in contact with the rocks and the 

- lack of significant evaporation. Mean alkalinity as HCO3 is 322 mg/L, which indicates good 

acid-neutralizing capacity probably because of abundant carbonate minerals in the rocks. 

Because of the high alkalinity values, the areas underlain by rocks of the Minturn and Belden 

Formations are moderately resistant to introduced acidification. The chemical quality of the 

waters from watersheds underlain by Pennsylvanian Minturn and Belden Formations is good. 

15
14

13 27 

26 

Middle

Prong

Ck 

South

Prong

Ck 

Big

Cotto

nwood

Ck 

Cotopaxi

Arkansas River

Hayden Ck 

0 1 2 3 Miles 

105 45’ o 

38 30’ o 

PPI s

PPI s

I Pmb

Stream Site 

PPI s Sangre de Cristo Formation 

IPmb Minturn and Belden Formation 

Figure 4. Locatins of waters from stream sites in the northern 

Sangre de Cristo Range. Geology generalized from 

Tweto (1979). 

16
PmI b

PmI b

PsI c

Garner Ck

Major Ck 

Electria Pk 

Gibson Ck 

Verde Ck 

Middle Ck 

Alvarado Ck 

Henneguin Ck 

Horn Ck 

Dry Ck 

Colony Ck 

28 

29 

17 

20 

23 22 

21 

19 

24 

25 

18 

Horn Pk + 

+ 

38o 

105 45’ o 

Sangre De C risto Range 

0 1 2 3 Miles

Stream Site 

IPsc Sangre de Cristo Formation 

IPmb Minturn and Belden Formatins 

Figure 5. Locations of water samples from streams from the Sangre de 

Cristo Range. Geology generalized from Tweto (1979). 

17
Table 5. Summary of selected water chemistry of six streams in watersheds 

underlain by Pennsylvanian Minturn and Belden Formations in the 

Sangre de Cristo Range (n=6). Conductivity in μS/cm, alkalinity 

mg/L HCO3, TDS, Ca, Mg, Na, K, Si, SO4, Cl, F, and N in mg/L, 

remaining elements in μg/L. Values below level of detection were 

replaced with values of 0.7 the level of detection 

Measurement Range Mean 

Minimum Maximum 

Conductivity

TDS

pH

Ca

Mg

Na

K

Si

Alkalinity

SO4

Cl

F

N

Al 

Fe

Mn

Cu

Zn

Mo

Cr

Ni

U

Li

Ba

Sr

235 632 429 

197 469 334 

7.11 8.56 8.15 

31 91 57 

11 30 19 

1.3 4.7 3.2 

0.64 3.2 1.3 

3.1 7 5.2 

285 444 322 

6.2 169 64 

<1 1.3 <1 

<0.05 0.15 0.09 

<0.05 0.07 <0.05 

0.88 6.3 2.3 

1 5 2 

0.3 7.6 0.6 

<0.5 0.9 0.5 

0.5 19 1.1 

0.53 8.1 1.8 

<1 3.2 1 

0.9 2.6 1.7 

1 1.8 1.3 

0.5 4.5 1.9 

38 47 42 

120 1310 472 

18
Evaporitic Facies in the Eagle Valley and South Park Areas 

Samples of water draining Evaporite Facies rocks were collected form five streams and 

three springs in the Eagle Valley and two streams and one well in the South Park area (figs. 6, 7 

and 8). Because the water samples were from areas underlain with rocks containing evaporite 

minerals, particularly gypsum, the samples from the two areas were lumped together. The 

watersheds in the Eagle Valley are underlain by Pennsylvanian Eagle Valley Evaporite of 

gypsum, anhydrite and interbedded siltstone and minor dolomite and Pennsylvanian Eagle 

Valley Formation of siltstone, shale, sandstone, carbonate, and lenses of gypsum (Tweto, 1979). 

The watersheds of the South Park area are underlain by the evaporite facies member of the 

Pennsylvanian Minturn and Belden Formations (Tweto, 1979). Relief varies from high in the 

Eagle Valley and moderate to low in the South Park area. The dominant vegetation is western 

spruce-fir forest in the higher areas and juniper-pinyon scrub and sagebrush along the flanks and 

Eagle Valley and alpine meadow and grasslands in South Park (Kuchler, 1965). Annual 

precipitation ranges from 12 to 30 inches in the Eagle Valley and 12 to 25 inches in South Park 

(Colorado Climate Center, 1984). The ranges and means of selected species in the waters are 

- shown in Table 6. The sites contain nine Ca2+- HCO3 and two Ca2+-SO42-

type waters with 

alkaline pH values. Mean pH is 8.09 and mean conductivity is 685 :S/cm. Mean TDS value is 

higher than average river water (Table 3) with a mean of 334 mg/L. Trace metal concentrations 

are low. Mean concentrations of Al, Fe, and Mn are moderately low with means of 2.7, 10, and 

4.1 :g/l, respectively. Other trace metal concentrations are low. Mean Zn, Cu, Mo, and U are 

1.7, 1, 1.8, and 1.5 :g/l, respectively. Mean Si concentration 7.5 mg/L. Mean Cl concentration 

is 3.6 mg/L, which is slightly higher than the waters from the other rock composition types 

probably because of the presence of minor halite in the Evaporite Facies rocks. Mean alkalinity 

is 369 mg/L, which indicates good acid-neutralizing capacity probably because of abundant 

carbonate minerals in the rocks. Because of the high alkalinity values, the areas underlain by 

rocks containing evaporite minerals are moderately resistant to introduced acidification. The 

19
34 

33 

32 

31 Gore Ck 

Eagle River 

Berry 

Ck 

Beaver Ck 

McCoy Ck 

Vail 

Avon 

Edwards 

0 1 2 3 Miles 

106 30’ o 

39 30’ o 

Pmb 

Pe, 

PC 

I 

_ 

I 

PmI b

PeI e

Pe, I PeI e Eagle Valley Formation and Evaporitic Facies 

Minturn and Belden Formations Stream Site 

Precambrian Rocks 

PmI b

PC_ 

Figure 6. Locations of water samples from steams in the Upper 

Eagle River Valley. Geology is generalized from 

Tweto (1979). 

20
39 

Cottonwood

Ck 

Gypsum Ck 

Gypsum Eagle 

Eagle River 

41 

38 

37 

36 

40 

Eby Ck 

Cottonwood Ck 

Colorado River 

39 30’ o 

107o 0 5 Miles 

Stream Site 

Spring Site 

PeI 

P PI m

PPI m Maroon Formation 

PeI Evaporitic Facies

Figure 7. Locations of water samples from stream and spring sites in the 

lower Eagle River Valley. Geology generalized from Tweto (1979). 

21
1 

2 

3 

So. Fk. South Platte

Rough and Tumblin Ck 

Pike National Forest Antero Resv. 

0 1 2 Miles 

39

O 

106

O 

Stream Site 

Well Site 

Pmb I e

Pmb I 

Pike National 

Forest 

Pmb I e Evaporitic Facies of Minturn and 

Belden Formations of South Park 

Pmb I Minturn and Belden Formations 

Figure 8. Locations of water samples from stream and well sites in South 

South Park. Geology generalized from Tweto (1979). 

22
Table 6. Summary of selected water chemistry of eight streams, two springs and one 

well in watersheds underlain by Pennsylvanian Evaporite Facies rocks in Eagle 

Valley and South Park (n=11). Conductivity in μS/cm, alkalinity as mg/L 

HCO3, TDS, Ca, Mg, Na, K, Si, SO4, Cl, F, and N in mg/L, remaining 

elements in μg/L. Values below level of detection were replaced with values 

of 0.7 the level of detection 

Measurement Range Mean 

Minimum Maximum 

Conductivity

TDS

pH

Ca

Mg

Na

K

Si

Alkalinity

SO4

Cl

F

N

Al 

Fe

Mn

Cu

Zn

Mo

Cr

Ni

U

Li

Ba

Sr

232 2020 685 

169 1757 528 

7.49 8.65 8.09 

30 387 103 

7 74 21 

2.7 60 7.8 

<0.5 5.6 1.2 

3.8 14 7.5 

177 575 369 

19 972 155 

<1 24 3.6 

<0.05 0.89 0.08 

<0.05 0.07 <0.05 

0.88 8.2 2.7 

1 20 10 

0.06 441 4.1 

<0.5 2.3 1 

<0.5 123 1.7 

0.5 8.6 1.8 

<1 3.8 1 

1.1 14.4 3.2 

0.37 6.1 1.5 

<0.1 110 4 

20 116 56 

215 4720 1071 

23
chemical quality of the waters from watersheds underlain by Evaporite Facies rocks is good 

except for moderately high total dissolved solids. 

Sangre de Cristo Formation in the Sangre de Cristo Range 

Water samples were collected from 11 streams in the Sangre de Cristo Range within the 

San Isabel and Rio Grande National Forest (figs. 5 and 9). The watersheds are underlain by 

Permian and Pennsylvanian Sangre de Cristo Formation of conglomerate, arkose, sandstone, 

siltstone, and minor shale and limestone (Johnson, 1969). Relief is high and the dominant 

vegetation is pine-Douglas fir and western spruce-fir forest in the higher areas and juniperpinyon woodland along the lower flanks (Kuchler, 1965). Annual precipitation ranges from 16 

to 40 inches (Colorado Climate Center, 1984). The ranges and means of selected species in the 

- waters are shown in Table 7. The sites contain Ca2+- HCO3 type waters with alkaline pH 

values. Mean pH is 7.86 and mean conductivity is 172 :S/cm. Mean TDS value is higher than 

average river water (Table 3) with a mean of 137 mg/L. Mean concentrations of Al, Fe, and Mn 

are low with means of 1.6, 2, and 0.23 :g/l, respectively. Other trace metal concentrations are 

low. Mean concentrations of Zn, Cu, Mo, and U are <0.5, <0.5 , 0.26, and 0.35 :g/l, 

respectively. Mean Si concentration is 3.4 mg/L. The low mean compared to average waters is 

probably due to the rock type which contains abundant course silicate grains which are less 

soluble than finer grain silicate minerals. Mean Cl concentration is < 1 mg/L, which is low and 

reflects the short residence time of the water from melting snow and rain in contact with the 

rocks and the lack of significant evaporation. Mean alkalinity is 172 mg/L, probably because of 

the presence of minor carbonate minerals in the rocks and indicates acid-neutralizing capacity. 

The chemical quality of the waters from watersheds underlain by Permian and Pennsylvanian 

Sangre de Cristo Formation is good. 

Comparison of Water Chemistry from each of the Five Rock Groups 

The chemistry of water evolving in watersheds depends on the chemical composition of 

24
Psc 

Psc 

Pmb I I 

I 

Hudson Branch

15 

16 

38o 

105 45’ o 

M usic Pass Ck 

Co lony Ck 

Sangre De C risto Range 

0 1 2 3 Miles

Stream Site 

Psc Sangre de Cristo Formation 

Pmb Minturn and Belden Formation 

Figure 9. Locations of water samples from streams in the 

Sangre de Cristo Range. Geology is generalized 

from Tweto (1979). 

25
Table 7. Summary of selected water chemistry of 11 streams in watersheds underlain by 

Permian and Pennsylvanian Sangre de Cristo Formation in the Sangre de Cristo 

Range (n=11). Conductivity in μS/cm, alkalinity as mg/L HCO3, TDS, Ca, Mg, 

Na, K, Si, SO4, Cl, F, and N in mg/L, remaining elements in μg/L. Values 

below level of detection were replaced with values of 0.7 the level of detection. 

Measurement Range Mean 

Minimum Maximum 

Conductivity

TDS

pH

Ca

Mg

Na

K

Si

Alkalinity

SO4

Cl

F

N

Al 

Fe

Mn

Cu

Zn

Mo

Cr

Ni

U

Li

Ba

Sr

63 294 172 

58 246 137 

7.13 8.99 7.86 

6.9 39 24 

1.9 11 4.1 

1 5.7 1.9 

<0.5 0.57 <0.5 

1.5 6.6 3.4 

81 359 179 

1.8 55 6.6 

<1 <1 <1 

<0.05 0.14 <0.05 

<0.05 <0.05 <0.05 

0.22 11 1.6 

<1 16 2 

<0.01 4.4 0.23 

<0.5 0.6 <0.5 

<0.5 1 <0.5 

<0.2 1.4 0.26 

<1 14 1.1 

0.3 1.2 0.7 

0.03 1.9 0.35 

0.6 304 1.1 

15 186 66 

36 364 121 

26
the underlying rock type. A unique range of water chemistry evolves within each of the five 

rock groups (Table 1). Values of TDS can be used to compute the rate at which rivers transport 

chemical weathering products to the ocean and therefore chemical weathering rates at a point in 

time but not an annual rate. Even so, TDS values can be used to compare waters from different 

geologic terrains as a means of comparing chemical weathering rates. Mean TDS values for 

waters from the five areas are shown in Table 1. Waters with the highest mean TDS values 

evolve from areas underlain by Evaporite Facies rocks in the Eagle Valley and South Park 

followed by Minturn and Belden Formations in the Sangre de Cristo Range, Minturn and Belden 

Formations in the Flat Tops area, Minturn and Belden Formations in the Redcliff area, and 

Sangre de CristoFormation in the Sangre de Cristo Range. The areas underlain by Evaporite 

Facies rocks in the Eagle Valley and South Park are undergoing by far the most rapid rate of 

chemical weathering, supplying the most dissolved solids to the waters of the area. This is not 

surprising because these rocks contain evaporite minerals, particularly gypsum, which are readily 

soluble. Watersheds underlain by Pennsylvanian Sangre de CristoFormation in the Sangre de 

Cristo Range are undergoing the lowest rate of chemical weathering and supplying the lowest 

amounts of dissolved solids to the waters of the area. These rocks contain sandstones and 

conglomerates more resistance to weathering and lack the more soluble carbonate and evaporite 

minerals such as gypsum of the other rock groups. 

Alkalinity of a solution is the capacity for solutes it contains to react with and neutralize 

acid (Hem, 1992). The property of alkalinity is determined by titration with a strong acid. 

Several different solute species may contribute to alkalinity, but for almost all natural fresh 

waters, the alkalinity is produced by the dissolved carbon dioxide species, bicarbonate and 

carbonate (Hem, 1992). Alkalinity in this study is reported as equivalent amounts of bicarbonate 

and is a measure of the capacity of the water to react with and consume acid. If an area is 

affected by introduced acidity from sources such as acid mine drainage or acid rain, the alkalinity 

will consume the introduced acid. If all the alkalinity is consumed and acidity is still being 

introduced, the acidity of the water will increase. The higher the alkalinity value, the greater the 

capacity of the water to consume acid. The mean alkalinity values of waters from areas 

- underlain by the five rock groups range from 179 to 402 mg/L as HCO3 (Table 1). The waters 

27
with the highest alkalinity values are from areas underlain by Minturn and Belden Formations in 

the Flat Tops area, followed by Evaporite Facies in the Eagle Valley and South Park, Minturn 

and Belden Formations in the Redcliff area, and Minturn and Belden Formations in the Sangre 

de Cristo Range. The lowest alkalinity values are from areas underlain by Sangre de Cristo 

Formation in the Sangre de Cristo Range. The waters from areas underlain by Minturn and 

Belden Formations and the Evaporite Facies are very well buffered and have large capacity to 

neutralize acidity. 

Mean pH values of waters from areas underlain by the five rock groups are all alkaline 

and range from 7.82 to 8.33 (Table 1). In addition to rock type, pH values in these headwater 

streams are affected by the amount of melting snow runoff as a component of the total flow and 

the time of contact of water and rock. The snow runoff will generally lower the pH, and the time 

of contact of water and rock will generally increase the pH value. In addition, high biotic 

activity in the soil zone may release organic acids and may lower pH. The lowest mean pH 

values are from Belden and Minturn Formations in the Flat Tops area and the Sangre de Cristo 

Formation in the Sangre de Cristo Range. Both areas have the large components of snow runoff 

which probably accounts for the lower pH values compared to the remaining rock groups. 

Mean concentrations of Si in waters from areas underlain by the five rock groups range 

from 3.3 to 7.5 mg/L (Table 1). These values are low for four of the rock groups compared to 

average fresh water of 6.1 mg/L (Table 3). The highest mean value is from areas underlain by 

evaporites, probably because these rocks contain fine-grained silicate minerals with high surface 

areas, particularly susceptible to the dissolution of silica. The other four rock types contain 

coarser grain-size silicate minerals which are more resistant to weathering. 

Mean concentrations of Cu, Zn, Fe, Mn, and Mn in waters from the five rock groups are 

low (Table 1), compared to average fresh water (Table 3). Mean Mo concentrations are low 

except from areas underlain by Minturn and Belden Formations from the Sangre de Cristo Range 

and Evaporite Facies from Eagle Valley and South Park. Mean U is high for all rock groups 

except the Sangre de Cristo Formation and mean Cr and Ni concentrations are high for the five 

rock groups (Table 1). Mean sulfate concentrations are high for the five rock groups compared 

to fresh water except for waters from areas underlain by Minturn and Beldon Formations in the 

28
Flat Tops area and the Sangre de Cristo Formation in the Sangre de Cristo Range. Waters from 

areas underlain by Minturn and Beldon Formations in the Flat Top area is low in sulfate probably 

because of the large component of snow melt in the waters. The source of sulfate in waters is 

probably gypsum in all the rock types except for waters from the Sangre de Cristo Formation in 

the Sangre de Cristo Range. By far the highest mean sulfate in waters (155 mg/L) is from areas 

underlain by Evaporite Facies in Eagle Valley and South Park, which contains the highest 

amounts of gypsum. Mean Li concentrations are high except from areas underlain by Minturn 

and Belden Formations in the Eagle Valley. Mean nitrate values are low for all waters 

suggesting little or no anthropogenic contamination. 

A comparison of water chemistry from the three areas underlain by Minturn and Belden 

Formations shows that waters from areas underlain by Minturn and Belden Formations in the 

Sangre de Cristo Range have the highest TDS values and sulfate concentrations (Table 1). The 

likely source of the sulfate is gypsum, so these rocks probably contain more evaporite minerals, 

particularly gypsum, than the other two areas. The waters from the Flat Tops area contained the 

lowest amount of sulfate, and this area probably contains the least amount of evaporite minerals 

of the three areas containing Minturn and Belden Formation rocks. But waters from the Flat Top 

area contain the highest alkalinity (Table 1) indicating that these waters are in contact with more 

carbonate rocks than the other two areas. 

Chemical Modeling of the Waters 

To gain understanding of processes such as speciation of elements and identification of 

minerals that may control the concentration, mobility, and attenuation of elements in the stream 

waters, chemical modeling of the waters was carried out using PHREEQC (Parkhurst, 1995). 

The modeling program assumes mineral-solution equilibrium. For some chemical reactions, 

particularly with slow kinetics, this may not be the case. Except for Al, most of the cations in the 

stream waters occur mostly as simple cations and the anions as chloride, sulfate, carbonate, and 

0 bicarbonate complexes (Table 8). Si occurs as the uncharged specie H4SiO4 . In addition, the 

state of saturation of the waters with mineral phases were calculated. Saturation indices were 

29
Table 8. Dominant species of selected elements in waters 

Element Specie 

Ca 

Mg 

Na 

K 

S 

C 

Cl 

F 

Si 

Al 

Fe 

Mn 

Ca2+ 

Mg2+ 

Na+ 

K+ 

SO4

2-

- HCO3 

ClFH4SiO4

0 

- Al(OH)4

Fe2+, FeCO3

0

, Fe(OH)3

0

Mn3+, MnCO3

0

30
 calculated for a suite of minerals to determine if concentrations of trace metals in water were 

controlled by mineral phases. The saturation index is a convenient means of expressing 

saturation states of minerals (Barnes and Clark, 1969) where: 

SI=log10 IAP/KT. 

In the expression, SI is the saturation index, IAP is the ion activity product, and KT is the 

equilibrium constant of the dissolution reaction at the temperature of the sample. Mineral phases 

are supersaturated at SI>0, saturated at SI=0, and undersaturated at SI<0. 

Each water sample was modeled and the results for selected minerals are shown in Table 

9. Waters from areas underlain by the five rock groups are mostly supersaturated or near 

saturated with respect to calcite. Many are supersaturated or near saturation with respect to 

barite and dolomite. These minerals appear to control the solubility of Ca, Mg, Ba, and 

alkalinity. Another mineral which has an influence on the control of species in water is 

chalcedony. The waters from all the rock groups are slightly undersaturated with respect to 

chalcedony, which appears to control the amount of dissolved silica in the waters. The waters 

are all undersaturated with respect to other minerals such as siderite, gypsum, fluorite, sepiolite, 

and rhodochrosite except for one water supersaturated with respect to sepiolite from Evaporite 

Facies rocks in South Park. Of the five rock groups, waters from Evaporite Facies rocks in the 

Eagle Valley and South Park come closest to saturation with respect to gypsum, which is not 

surprising since these rocks contain abundant gypsum. 

Comparison of Water Chemistry of Two Streams From Above and Below Contact with 

Evaporite Facies Rocks and Potential Environmental Problems Associated with 

Construction in the Eagle Valley 

The changes of water chemistry of a stream as it crosses the contact and comes into 

contact with Evaporite Facies rock are shown for Eby and Beaver Creeks (fig.10). Upper Eby 

31
Table 9. Saturation indices for selected minerals for waters from Permian and Pennsylvanian 

Rocks, Western Colorado 

Site Barite Calcite Chalcedony Dolomite Gypsum Rhodochrosite Sepiolite Siderite 

Minturn and Belden Formations in the Redcliff Area 

CC43 0.56 

CC44 0.41 

CC45 -1.28 

CC46 -1.41 

CC47 -1.02 

CC48 -1.39 

CC49 -1.33 

CC50 -1.16 

1.14 -0.32 1.56 -1.31 -1.87 -2.02 -1.64 

1.07 -0.33 1.41 -1.4 -2.52 -2.19 -1.64 

0.37 -0.48 -0.65 -3.13 -1.06 -6.78 -1.24 

0.21 -0.4 -1.02 -3.38 -3.01 -7.23 -2.8 

0.89 -0.4 0.52 -3.18 -0.86 -4.51 -1.31 

0.23 -0.4 -1.07 -3.27 -1.75 -7.52 -1.9 

0.34 -0.39 -1.06 -3.29 -1.63 -7.24 -2.66 

0.19 -0.31 -1.3 -3.29 -3.96 -6.97 -2.72 

Minturn and Belden Formations in the Flat Top Area 

CC05 0.29 

CC06 0.54 

CC07 -0.2 

CC08 -0.31 

CC09 -0.22 

CC10 -0.76 

CC11 -0.79 

0.63 -0.44 1.08 -2.65 -2.8 -2.04 -2.85 

1.04 -0.35 1.51 -1.46 -2.35 -1.98 -2.95 

0.78 -0.54 1.09 -2.62 -2.31 -2.6 -2.1 

0.9 -0.56 1.65 -2.85 -1.26 -1.37 -1.45 

1.15 -0.57 1.84 -2.62 -2.67 -1.06 -1.87 

0.13 -0.61 -0.22 -2.93 -1.62 -6.12 -2.25 

0.63 -0.57 0.26 -3.39 -2.9 -3.71 -2.11 

Minturn and Belden Formations in the Sangre de Cristo Range 

CC13 -0.09 

CC14 -0.78 

CC26 0.32 

CC27 0.41 

CC28 0.22 

CC29 0.23 

0.69 -0.42 1.29 -2.3 -2.29 -1.59 -1.58 

0.64 -0.59 1 -3.04 -2.18 -2.73 -1.97 

0.82 -0.37 1.18 -1.4 -2.59 -2.29 -1.76 

-0.18 -0.27 -0.85 -1.31 -3.43 -6.35 -2.77 

1.28 -0.22 2.33 -1.6 -1.7 -0.04 -1.11 

0.98 -0.26 1.57 -1.58 -0.89 -1.1 -1.16 

32
Site Barite Calcite Chalcedony Dolomite Gypsum Rhodochrosite Sepiolite Siderite 

Evaporite Facies of Eagle Valley and South Park 

CC01 0.62 1.31 -0.07 2.45 -0.68 -0.09 -0.61 -0.77 

CC02 0.1 0.52 -0.02 -0.36 -2.39 -1.34 -2.96 -1.69 

CC03 0.03 1.34 -0.37 2.45 -1.62 -1.13 0.2 -1.67 

CC31 -0.19 0.17 -0.43 -0.15 -2.34 -1.23 -3.66 -1.03 

CC33 0.33 1.14 -0.52 1.79 -1.18 -0.06 -1.61 -0.57 

CC34 0.87 1.21 -0.3 1.76 -1.08 -1.89 -1.46 -1.42 

CC36 0.47 1.44 -0.18 2.65 -1.02 -0.87 -0.26 -0.48 

CC38 3.52 0.87 0.04 1.23 -0.31 0.31 -2.87 -1.28 

CC39 0.22 0.2 -0.24 -0.1 -2.22 -3.11 -3.84 -2.37 

CC40 0.29 0.58 -0.22 0.21 -0.91 -3.49 -4.36 -2.23 

CC41 0.67 1.28 -0.1 2.01 -1.13 -1.01 -1.39 -0.7 

Sangre de Cristo Formation in the Sangre de Cristo Range 

CC15 -1.6 -1.26 -0.37 -2.96 -4.04 -2.65 9.16 -1.86 

CC16 -0.95 -0.85 -0.28 -2.46 -3.5 -2.67 -7.68 -2.88 

CC17 -0.41 -0.11 -0.78 -0.9 -2.91 -2.2 -5.36 -1.03 

CC18 -0.2 1.01 -0.99 1.6 -2.09 -1.01 -1.37 -1.03 

CC19 0.1 0.09 -0.89 -0.33 -2.12 -2.79 -5.28 -2.59 

CC20 -0.37 0.48 -0.3 0.15 -3.23 -2.29 -3.41 -2.27 

CC21 -0.38 -0.47 -0.7 -1.62 -3.12 -3.07 -6.87 -2.57 

CC22 -0.75 -0.56 -0.7 -1.73 -3.19 -4.6 -7.19 -3.03 

CC23 -0.48 -0.16 -0.33 -1.06 -3.24 -3.46 -5.67 -2.79 

CC24 -0.65 0.09 -0.4 -0.47 -3.32 -2.53 -5.1 -2.7 

CC25 -0.19 0.5 -0.24 0.57 -2.97 -4.08 -3.04 -1.91 

Eby and Beaver Creeks 

CC32 -1.42 -1.25 -0.46 -2.81 -3.99 -2.59 -6.58 -2.56 

CC37 -1.15 0.28 -0.09 0.06 -3.18 -0.99 -4.79 -1.65 

33
37 

36 

Eagle Creek 

Eby Cr eek 

Pe 

PPwI m

I 

0 

5 

8 

1 

Site 37 6 

7.36 8.3

482.7 841.

84.1 141.

524 562 

93.6 32

Site 3

pH 

TDS 

Calcium 

Alkalinity 

Sulfate 

Eagle Creek 

31 

32 

Pee 

Pmb 

pC 

B

e

av 

er C re

ek 

I 

I 

-

6 

Site 32 1 

7.55 8.0

55.7 169.3 

6.8 30.1 

78 177 

2.15 30.3 

Site 3

pH 

TDS 

Calcium 

Alkalinity 

Sulfate 

Figure 10. Increases in water chemistry from above to below contact with Evaporite 

Facies rocks of two streams. Units for conductivity in S/cm, : alkalinity

in mg/L bicarbonate, and calcium and sulfate in mg/L. 

34 
Creek is underlain by Permian and Pennsylvanian Weber Sandstone and Maroon Formation and 

to a lesser extent by Cretaceous Dakota Sandstone and Colorado Group (Tweto, 1979). Site 37 

(fig. 10) represents the stream water chemistry above the contact with Evaporite Facies rocks. 

Below this site the stream crosses into Evaporite Facies rocks and site 36 shows the impact of 

these rocks on water chemistry. TDS, pH, Ca, alkalinity, and sulfate all increase significantly. 

The largest increase is in sulfate (243%). The source of the sulfate is likely gypsum within the 

Evaporite Facies rocks. Ca concentration increases (69%), but not as much as the sulfate 

concentration. Congruent dissolution of gypsum would cause Ca and sulfate to increase 

similarly, but this is not the case. The stream water above site 37 is saturated with respect to 

calcite (table 9), which controls the Ca concentrations. As Ca is released by the dissolution of 

gypsum, much of this extra Ca is precipitated as calcite. So the increase in Ca does not keep 

pace with the increase in sulfate. The significant change in water chemistry between site 37 and 

site 36 illustrates the degradation of the waters resulting from contact with Evaporite Facies 

rocks and, in particular, gypsum. Increase in sulfate concentration is the main impact on the 

stream water chemistry. TDS values increase to a lessor extent (74%). 

Upper Beaver Creek above site 32 drains areas underlain mainly by Precambrian rocks 

and to a lesser extent Minturn and Belden Formations rocks (Tweto, 1979). The dramatic 

increase in water chemistry can be seen between site 32 and site 31 after the stream comes into 

contact with Evaporite Facies rocks (fig.10). Again, there is a general degradation of stream 

water chemistry. 

Within the Eagle River Valley from westward from the towns of Avon to Gypsum, 

significant construction of ski areas, golf courses, and houses are taking place at a rapid pace. 

Much of the water for snow making for the ski areas and irrigation for golf courses and homes is 

being obtained from tributaries of Eagle River. Much of this new construction is on Evaporite 

Facies rocks. The use of the water, particularly for snow making and irrigation, will probably 

impact the water chemistry by causing an increase in TDS in the Eagle River and the 

downstream Colorado River. Some of the tributaries have formed wide flat areas at their mouths 

before entering the Eagle River, mainly because of the presence of easily eroded Evaporite 

Facies rocks. These wide flat areas are ideal locations of golf courses with surrounding homes. 

35
This land use will require large amounts of water for irrigation and has the potential to 

significantly impact the water quality in terms of an increase in TDS of the Eagle River and the 

downstream Colorado River. Irrigation of the golf courses and yards of the homes will cause 

chemical degradation of the Eagle River during the summer. The melting of snow made by 

snow making will also cause chemical degradation of the Eagle River in the spring in this area. 

Summary and Conclusions 

This study determines ranges and means of baseline geochemistry of stream and spring 

waters that evolve within each of five rock groups of Permian and Pennsylvanian rocks in 

western Colorado. By comparing the geochemistry of the waters that evolve in each of the five 

rock groups, a rationale can be developed for characterizing and ranking the rock groups as to 

their release of TDS (a measure of chemical weathering) and their acid-neutralizing capacities. 

Also, processes responsible for the control and mobility of elements in water and the potential 

environmental impact of development in the Eagle Valley are discussed. The following are the 

most significant conclusions based on these results: 

< 1. The baseline geochemistry of stream and spring waters evolving in the headwater areas 

depends on the chemical composition of the underlying rock type. Within each rock 

compositional type, a unique range of water compositions evolve. Other factors such as 

annual precipitation, temperature, topographic setting, character of minerals (e.g., grain 

size and crystallinity), and biotic activity can be important, but mainly influence the rates 

of chemical reactions and not the type of elements present in the waters. 

- < 2. The waters that evolve in these five rock groups are mainly Ca2+- HCO3 type waters, 

with alkaline pH values and high TDS values. Dominant species present in the water 

samples are Ca2+, Mg 2+, Na+

, K+, SO4

2-

, HCO3

-

, Cl-, F-, H4SiO4

0

, Al(OH)4 

-

, Fe2+, and 

Mn2+. 

36
< 3. TDS values, which are an approximate measure of the chemical weathering rates, 

indicate that waters with the highest TDS values evolve from watersheds underlain by 

Evaporite Facies rocks in Eagle Valley and South Park. This is not surprising because 

these formations contain soluble evaporite minerals such as gypsum. Waters with the 

lowest TDS values evolve from watersheds underlain by the Sangre de Cristo Formation. 

These rocks contain abundant coarse grained sediments which are more resistant to 

weathering. 

< 4. Alkalinity is a measure of the acid-neutralizing capacity of waters to introduced 

acidification. The waters with the highest alkalinity values are from areas underlain by 

Minturn and Belden Formations in the Eagle Valley, followed by Evaporite Facies in the 

Eagle Valley and South Park, Minturn and Belden Formations in the Redcliff area, and 

Minturn and Belden Formations in the Sangre de Cristo Range. The lowest alkalinity 

values are from areas underlain by Sangre de Cristo Formation in the Sangre de Cristo 

Range. All the waters contain significant alkalinity and are well buffered. The waters 

from the Minturn and Belden Formations and the Evaporite Facies have large capacity to 

neutralize acidity. 

< 5. Mean values for pH of waters from areas underlain by the five rock groups are all 

alkaline and range from 7.82 to 8.33. The lowest mean pH values are from Belden and 

Minturn Formations in the Flat Tops area and the Sangre de Cristo Formation in the 

Sangre de Cristo Range. Both areas have large components of snow runoff which 

probably accounts for the lower pH values compared to the remaining rock groups. 

< 6. The mean sulfate values are high compared to average fresh water from all the areas 

except waters from the Minturn and Beldon Formations in the Flat Tops area and the 

Sangre de Cristo Formation in the Sangre de Cristo Range. By far the highest sulfate 

values are from areas underlain by Evaporite Facies in Eagle Valley and South Park, 

mainly because of the presence of gypsum. 

37
< 7. Mean concentrations of Cu, Zn, Fe, Mn, and Mn in waters from the five rock groups 

are low and the mean concentrations of Ni and Cr are high compared to average fresh 

water. Mean concentrations of U is high for all rock groups except the Sangre de Cristo 

Formation. 

< 8. Evaporite minerals are present in the Minturn and Belden Formations in the Redcliff 

area, the Flat Tops areas, and Sangre de Cristo Range. The amounts vary but are 

generally much less than Evaporite Facies rocks. 

< 9. Development of golf courses, homes, and ski areas in the Eagle Valley between Avon 

and Gypsum has led to the diversion of water, particularly of tributaries of the Eagle 

River, for irrigation and snow making. In areas where this development overlies 

Evaporite Faies rocks, the irrigation and snow making has probably lead to an increase in 

TDS and a lowering of water quality of the Eagle River and downstream Colorado River. 

The unique geochemical baselines from the five rock groups demonstrates the importance 

of rock composition in determining the types of waters that are evolving in headwater areas. 

These geochemical baselines provide ranges and means of values that approximate the natural 

baseline geochemistry of the stream and spring waters in these watersheds for each of the five 

rock groups. In addition, the comparison of these geochemical baselines with future baselines 

will allow the recognition of any significant changes in water quality that may occur. 

38
References Cited 

Apodoaca, L.E., Driver, N.E., Stephens, V.C., and Spahr, N.E., 1996, Environmental setting and 

implications on water quality, Upper Colorado River Basin, Colorado and Utah: WaterResources Investigations Report 95-4263, 33 p. 

Barnes, I. and Clark, F.E., 1969, Chemical properties of ground water and their corrosion and 

encrustation effects on wells: U.S. Geol. Survey Professional Paper 498-D, 58 p. 

Colorado Climate Center, 1984, Colorado average annual precipitation 1951-1980: Compiled by 

Climate Center, Dept. Atmospheric Science, Colorado State Univ., Fort Collins, 

scale1:500,000. 

Curtis, B. F., 1958, Pennsylvanian paleotectonics of Colorado and adjacent areas, in Curtis, B. 

F., ed. Symposium on Pennsylvanian rocks of Colorado and adjacent areas: Rocky 

Mountain Association of Geologists, p. 9-12. 

DeVoto, R. H., 1972, Pennsylvanian and Permian stratigraphy and tectonism in central 

Colorado: Quarterly of the Colorado School of Mines, v. 67, p. 139-185. 

Edwards, T. K. and Glysson, G. D., 1988, Field methods for measurement of fluvial sediment: 

U.S. Geological Survey Open-File Report 86-531, 118 p. 

Fishman, M.J. and Pyen, G., 1979, Determination of selected anions in water by ion 

chromatography: U.S. Geol. Survey Water Resources Invest. 79-101, 30 p. 

Forstner, U. and Wittmann, G. T. W., 1979, Metal pollution in the aquatic environment: Springer 

39
Verlag, 486 p. 

Hem, J.D., 1992, Study and interpretation of the chemical characteristics of natural water: U.S. 

Geological Survey Water-Supply Paper 2254, 263 p. 

Hunt, C.B., 1974, Natural regions of the United States and Canada: San Francisco, W.H. 

Freeman and Company, 725 p. 

Johnson, R. B., 1969, Geologic map of the Trinidad quadrangle, south-central Colorado: U.S. 

Geological Survey Misc. Geol. Inv. Map I-558. 

Kuchler, A. W., 1965, Potential natural vegetation of the conterminous United States: American 

Geographical Society Special Publication no. 36. 

Livingstone, D.A., 1963, Chemical composition of rivers and lakes: 6th ed., U.S. Geological 

Survey Professional Paper 440-G, 64 p. 

Mallory, W. W., 1971, The Eagle Valley Evaporite, northwest Colorado-a regional synthesis: 

U.S. Geological Survey Bulletin 1311-E, p. E1-E37. 

Miller, W.R., 1999, Geochemical baselines and maps showing acid-neutralizing capacity and 

potential release of total dissolved solids of stream and spring waters from different rock 

compositional types from mountainous watersheds in the Gunnison, Uncompahgre, and 

Grand Mesa National Forest, Colorado: U.S. Geological Survey Open-File Report 99-

580, 107 p. 

Orion Research, Inc., 1978, Analytical methods guide (9th ed.): Cambridge, MA, 48 p. 

Parkhurst, D.L., 1995, User’s guide to PHREEQC - a computer program for speciation, reactionpath, advective-transport, and inverse geochemical calculations: U.S. Geological Survey 

40
Water-Resources Investigations Report 95-4227, 143 p. 

Tweto, O., 1979, Geologic map of Colorado: U.S. Geological Survey Publication, scale 

1:1,500,000. 

U. S. Department of Agriculture, 1972, Natural vegetation , Colorado, scale 1:1,500,000. 

41
Appendix 1. Chemical analyses of waters from areas underlain by Permian and Pennsylvanian rocks, western 

Colorado. (PPsc) Sangre de CristoFormation, (PPwm) Weber Sandstone and Maroon Formation, (Pee) 

Evaporitic Facies, (Pe) Eagle Valley Formation, (Pmbe) Evaporitic Facies, (Pm) Minturn Formation, (Pmb) 

Minturn and Belden Formations, (MDr) Missippian and Devonian rocks, and (PC) Precambirian rocks 

(Tweto, 1979). 

Site Latitude Longitude Date Flow Comments 

deg. min. sec. deg. min. sec. 

Minturn and Belden Formations in the Redcliff Area 

CC05 39 32 14 106 23 26 7/19/00 3 gps Rock Creek 

CC06 39 35 52 106 25 34 7/19/00 10 gps Game Creek 

CC07 39 33 56 106 23 57 7/19/00 5 cfs Two Elk Creek 

CC08 39 31 0 106 21 43 7/19/00 10 gps Willow Creek 

CC09 39 31 23 106 20 9 7/19/00 3 cfs Lime Creek 

CC10 39 32 49 106 17 53 7/19/00 2 gps spring from wetland 

CC11 39 33 14 106 16 48 7/19/00 5gps stream 

Minturn and Belden Formations in the Flat Tops Area 

CC43 39 45 49 107 41 36 8/24/00 10 cfs Three Forks Creek

CC44 39 45 47 107 41 34 8/24/00 10 gps Rifle Creek

CC45 39 48 57 107 41 49 8/24/00 2 gps G V Spring

CC46 39 47 59 107 44 47 8/24/00 2 qt/sec spring 

CC47 39 46 13 107 45 29 8/24/00 3 gps Butler Creek

CC48 39 47 46 107 45 18 8/24/00 2 gps spring 

CC49 39 48 25 107 35 20 8/24/00 1 qt/sec Clark Cabin Spring

CC50 39 48 19 107 35 28 8/24/00 1 qt/sec spring 

Minturn and Belden Formations in the Sangre de Cristo Range 

CC13 38 19 30 105 49 12 8/14/00 5 gps South Prong Creek 

CC14 38 19 45 105 49 35 8/14/00 2 cfs Middle Prong Creek 

CC26 38 19 2 105 45 17 8/16/00 10 cfs Big Cottonwood Creek 

CC27 38 19 4 105 45 18 8/16/00 2 qt/sec Wolf Creek 

CC28 38 9 52 105 47 34 8/17/00 10 gps Major Creek 

CC29 38 10 34 105 48 10 8/17/00 2 cfs Garner Creek 

Evaporite Facies of Eagle Valley and South Park 

CC01 39 2 5 105 58 57 7/18/00 2 qt/sec stream

CC02 39 1 55 105 59 6 7/18/00 pump well at campground

CC03 38 59 6 105 59 3 7/18/00 5 gps stream

CC31 39 37 51 106 31 16 8/21/00 7 cfs lower Beaver Creek

CC33 39 38 0 106 33 45 8/21/00 7 gps McCoy Creek

CC34 39 39 12 106 35 5 8/21/00 10 gps Berry Creek

CC36 39 40 8 106 49 53 8/21/00 2 cfs lower Eby Creek

CC38 39 39 31 106 52 55 8/22/00 1 qt/sec spring in Cottonwood Creek

CC39 39 31 54 106 55 31 8/22/00 1 gps spring 

CC40 39 29 25 106 50 5 8/22/00 1 gps spring 

CC41 39 35 10 107 3 6 8/23/00 20 gps Cottonwood Creek
Site Latitude Longitude Date Flow Comments 

deg. min. sec. deg. min. sec. 

Sangre De Cristo Formation in the Sangre de Cristo Range 

CC15 37 50 52 105 26 26 8/15/00 3 cfs Mendano Creek

CC16 37 56 26 105 27 32 8/15/00 5 gps Music Pass Creek

CC17 37 59 42 105 29 26 8/15/00 10 cfs South Colony Creek

CC18 38 5 41 105 38 4 8/15/00 5 cfs upper Middle Taylor Creek

CC19 38 5 49 105 36 41 8/15/00 5 cfs Middle Taylor Creek

CC20 38 4 49 105 33 45 8/16/00 4 gps Alvarado Creek

CC21 38 2 17 105 32 11 8/16/00 8 cfs Horn Creek

CC22 38 3 17 105 32 24 8/16/00 5 gps Dry Creek

CC23 38 3 37 105 33 3 8/16/00 3 cfs Hennequin Creek

CC24 38 8 9 105 35 35 8/16/00 1 gps Gibson Creek

CC25 38 7 54 105 35 54 8/16/00 5 gps Verde Creek

Eby and Beaver Creeks 

CC32 39 35 51 106 31 18 8/21/00 6 cfs Beaver Creek 

CC37 39 41 30 106 49 52 8/22/00 1 gps Eby Creek 
Appendix 1. Chemical analyses of waters from areas underlain by Permian and Pennsylvanian rocks, western 

Colorado. (PPsc) Sangre de CristoFormation, (PPwm) Weber Sandstone and Maroon Formation, (Pee) 

Evaporitic Facies, (Pe) Eagle Valley Formation, (Pmbe) Evaporitic Facies, (Pm) Minturn Formation, (Pmb) 

Minturn and Belden Formations, (MDr) Missippian and Devonian rocks, and (PC) Precambirian rocks 

(Tweto, 1979). 

Site Geology Temperature pH TDS Conductivity Ca Mg Na 

Degree C mg/L μS/cm mg/L mg/L 

Minturn and Belden Formations in the Redcliff Area 

CC05 Pmb 6.9 8.37 228.8 272 29.3 16.2 2.2 

CC06 Pmb 7.7 8.31 426.1 564 85.6 19.4 2.3 

CC07 Pmb 8.7 8.38 225.2 288 39.6 10.8 1.4 

CC08 Pmb 11.3 8.57 221.0 269 32.1 16.0 1.4 

CC09 Pmb 8.8 8.80 226.5 281 38.9 10.4 1.3 

CC10 Pmb 14.1 7.47 260.0 314 47.3 10.2 1.3 

CC11 Pmb 8.5 8.43 158.6 187 30.7 2.5 1.5 

Minturn and Belden Formations in the Flat Tops Area 

CC43 Pm, MDr 7.4 8.31 479.0 633 108.2 17.6 2.0 

CC44 Pm, MDr 7.8 8.31 430.9 583 95.5 14.3 2.3 

CC45 Pm 10.2 7.63 270.3 333 64.6 2.0 0.9 

CC46 Pm 6.1 7.51 275.0 348 66.8 2.2 0.9 

CC47 Pm 9.6 8.06 313.8 377 73.3 3.1 1.3 

CC48 Pm 6.6 7.46 297.3 355 71.7 1.9 1.0 

CC49 Pmb 6.2 7.65 271.6 329 65.2 1.1 1.2 

CC50 Pmb 4.3 7.66 228.0 296 58.0 1.2 1.3 

Minturn and Belden Formations in the Sangre de Cristo Range 

CC13 Pmb 13.4 8.37 235.0 301 31.9 17.2 3.3 

CC14 Pmb 12.6 8.32 196.5 235 30.5 10.6 1.3 

CC26 Pmb 12 8.18 405.6 532 79.9 19.0 3.5 

CC27 Pmb 7.9 7.11 469.0 632 90.6 24.4 4.7 

CC28 Pm 10.7 8.56 444.9 552 72.0 30.3 4.5 

CC29 Pm 14 8.38 356.0 473 67.0 17.2 3.3 

Evaporite Facies of Eagle Valley and South Park 

CC01 Pmbe

CC02 Pmbe

CC03 Pmbe

CC31 Pee, Pm, pC

CC33 Pee, Pm

CC34 Pe, PPm

CC36 Pee, PPwm, others

CC38 Pee 

CC39 Pee 

CC40 Pee 

CC41 Pee 

23.3 8.01 1262.9 1416 212.9 67.3 59.9 

7.5 7.97 281.6 370 50.0 8.8 6.4 

22.5 8.65 362.0 462 66.5 18.0 6.0 

11.7 8.06 169.3 232 30.1 7.0 3.8 

13.6 8.43 492.6 904 104.7 21.2 4.3 

12.8 8.36 563.2 720 125.6 17.9 3.9 

18.4 8.30 841.5 994 141.8 45.2 31.7 

14.3 7.49 1757.3 2020 387.2 73.7 28.6 

6.7 7.87 232.1 292 39.4 11.1 2.7 

6 7.72 638.7 864 154.6 15.6 3.1 

13.5 8.14 675.5 841 142.4 26.1 5.7 
Site Geology Temperature pH TDS Conductivity Ca Mg Na 

Degree C mg/L μS/cm mg/L mg/L 

Sangre De Cristo Formation in the Sangre de Cristo Range 

CC15 PPsc 10.4 7.54 58.3 63 6.9 1.9 1.8 

CC16 PPsc, Pm 13 7.13 123.2 147 21.1 2.5 2.5 

CC17 PPsc 12.9 8.10 98.8 126 17.5 2.4 1.3 

CC18 PPsc, Pmb 16.3 8.99 167.5 237 32.3 7.2 1.2 

CC19 PPsc, Pmb 11.8 8.01 169.0 234 32.0 7.0 1.4 

CC20 PPsc, Pmb 9.8 8.18 180.8 216 33.7 4.0 3.9 

CC21 PPsc 9.6 7.65 110.0 140 19.7 3.2 1.2 

CC22 PPsc 11.8 7.53 110.1 142 19.1 3.4 1.0 

CC23 PPsc 7.9 7.63 165.4 208 31.0 4.7 2.1 

CC24 PPsc 12.8 7.73 181.3 223 34.0 5.1 2.5 

CC25 PPsc 10.9 8.01 246.1 294 39.4 10.6 5.7 

Eby and Beaver Creeks 

CC32 Pm, pC 11.5 7.55 55.7 67 6.8 2.4 1.4 

CC37 PPwm 9.5 7.36 482.7 593 84.1 20.5 12.4 
Appendix 1. Chemical analyses of waters from areas underlain by Permian and Pennsylvanian rocks, western 

Colorado. (PPsc) Sangre de CristoFormation, (PPwm) Weber Sandstone and Maroon Formation, (Pee) 

Evaporitic Facies, (Pe) Eagle Valley Formation, (Pmbe) Evaporitic Facies, (Pm) Minturn Formation, (Pmb) 

Minturn and Belden Formations, (MDr) Missippian and Devonian rocks, and (PC) Precambirian rocks 

(Tweto, 1979). 

Site K Si Alkalinity SO4 Cl F N Al 

mg/L mg/L mg/L HCO3 mg/L mg/L mg/L mg/L μg/L 

Minturn and Belden Formations in the Redcliff Area 

CC05 1.13 3.7 324 16.3 <1 <0.05 <0.05 3.21 

CC06 0.89 4.7 393 119 <1 0.05 <0.05 4.85 

CC07 0.53 3.1 317 13.1 <1 <0.05 <0.05 2.70 

CC08 0.61 3.3 319 9.94 <1 <0.05 <0.05 7.39 

CC09 0.51 3.0 320 14.3 <1 <0.05 0.08 3.90 

CC10 <0.5 3.1 389 5.80 <1 <0.05 0.08 2.09 

CC11 <0.5 2.9 239 2.46 <1 <0.05 <0.05 2.89 

Minturn and Belden Formations in the Flat Tops Area 

CC43 0.52 5.0 412 143 <1 0.10 0.33 2.23 

CC44 0.55 4.9 383 124 1.14 0.08 0.26 2.04 

CC45 <0.5 3.7 398 2.60 <1 <0.05 0.34 1.52 

CC46 <0.5 3.9 405 1.39 <1 <0.05 0.87 0.90 

CC47 <0.5 4.4 465 2.20 <1 0.06 <0.05 1.23 

CC48 <0.5 4.0 440 1.74 <1 <0.05 0.45 1.80 

CC49 <0.5 4.0 402 1.74 <1 <0.05 <0.05 1.95 

CC50 <0.5 4.6 326 1.83 <1 <0.05 0.49 1.39 

Minturn and Belden Formations in the Sangre de Cristo Range 

CC13 0.64 4.7 285 36.3 <1 0.07 <0.05 6.29 

CC14 0.91 3.1 291 6.22 <1 <0.05 <0.05 1.74 

CC26 1.30 5.1 295 151 1.03 0.13 0.07 1.20 

CC27 1.20 5.6 350 169 1.25 0.12 <0.05 0.88 

CC28 1.36 7.0 444 110 1.10 0.08 <0.05 4.07 

CC29 3.16 7.0 294 113 <1 0.15 <0.05 2.78 

Evaporite Facies of Eagle Valley and South Park 

CC01 5.61 13.7 538 615 24.0 0.9 <0.05 4.26 

CC02 0.83 9.8 373 18.6 3.79 0.16 <0.05 2.61 

CC03 0.97 7.2 307 111 1.30 0.09 <0.05 7.20 

CC31 0.95 4.4 177 30.3 5.74 <0.05 0.27 8.21 

CC33 1.23 3.8 281 216 3.18 0.07 <0.05 5.46 

CC34 0.94 6.1 342 239 1.36 <0.05 0.18 0.98 

CC36 3.27 9.6 562 321 12.4 0.2 <0.05 2.07 

CC38 2.83 13.8 525 972 21.3 0.1 <0.05 1.38 

CC39 <0.5 5.8 283 32.9 <1 <0.05 0.11 1.08 

CC40 <0.5 5.9 347 288 <1 0.05 0.19 0.88 

CC41 1.91 9.8 575 204 2.90 0.08 <0.05 5.53 
Site K Si Alkalinity SO4 Cl F N Al 

mg/L mg/L mg/L HCO3 mg/L mg/L mg/L mg/L μg/L 

Sangre De Cristo Formation in the Sangre de Cristo Range 

CC15 0.50 4.8 81 1.84 <1 0.14 <0.05 11.1 

CC16 <0.5 6.4 177 2.59 <1 0.07 <0.05 2.51 

CC17 <0.5 2.0 128 11.7 <1 <0.05 <0.05 6.43 

CC18 <0.5 1.5 141 54.9 <1 <0.05 <0.05 3.94 

CC19 <0.5 1.5 158 48.3 <1 <0.05 <0.05 1.33 

CC20 <0.5 5.6 263 3.39 <1 <0.05 <0.05 1.52 

CC21 <0.5 2.2 155 6.46 <1 <0.05 0.07 2.00 

CC22 <0.5 2.3 158 5.67 <1 <0.05 <0.05 0.22 

CC23 0.51 4.9 240 3.49 <1 <0.05 <0.05 0.49 

CC24 0.55 4.8 266 2.78 <1 <0.05 <0.05 1.01 

CC25 0.57 6.6 359 6.03 <1 <0.05 <0.05 0.48 

Eby and Beaver Creeks 

CC32 <0.5 4.0 78 2.15 <1 <0.05 <0.05 11.9 

CC37 2.05 8.8 524 93.6 3.05 0.17 <0.05 1.24 
Appendix 1. Chemical analyses of waters from areas underlain by Permian and Pennsylvanian rocks, western 

Colorado. (PPsc) Sangre de CristoFormation, (PPwm) Weber Sandstone and Maroon Formation, (Pee) 

Evaporitic Facies, (Pe) Eagle Valley Formation, (Pmbe) Evaporitic Facies, (Pm) Minturn Formation, (Pmb) 

Minturn and Belden Formations, (MDr) Missippian and Devonian rocks, and (PC) Precambirian rocks 

(Tweto, 1979). 

Site Fe Mn P Li ug/L Sc ug/L Ti ug/L V ug/L Cr ug/L 

μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L 

Minturn and Belden Formations in the Redcliff Area 

CC05 0.002 0.1 <0.01 4.1 0.9 < 0.1 0.3 < 1 

CC06 0.002 0.3 <0.01 3.7 1.1 1.3 0.4 < 1 

CC07 <0.001 0.3 <0.01 2.4 0.7 < 0.1 0.3 1.0 

CC08 0.002 2.8 <0.01 2.8 0.7 0.1 0.3 < 1 

CC09 <0.001 0.1 <0.01 2.1 0.6 0.1 0.3 < 1 

CC10 0.002 4.2 <0.01 2.0 0.6 < 0.1 0.3 1.0 

CC11 <0.001 0.08 <0.01 1.3 0.6 < 0.1 0.4 < 1 

Minturn and Belden Formations in the Flat Tops Area 

CC43 0.002 0.9 <0.01 2.8 1.1 2.1 1.1 2.8 

CC44 0.002 0.2 <0.01 2.9 1.1 1.8 1.0 2.3 

CC45 0.014 12.7 <0.01 0.3 0.8 0.2 1.7 2.4 

CC46 <0.001 0.2 0.019 0.5 0.8 < 0.1 1.4 2.5 

CC47 0.005 10.3 0.011 0.8 0.9 < 0.1 2.1 2.4 

CC48 0.005 3.8 0.016 0.3 0.8 < 0.1 1.7 2.8 

CC49 <0.001 3.7 0.014 0.3 0.9 < 0.1 2.5 2.6 

CC50 <0.001 0.02 0.018 0.3 0.9 < 0.1 2.6 2.1 

Minturn and Belden Formations in the Sangre de Cristo Range 

CC13 0.002 0.3 <0.01 4.1 1.0 0.8 0.4 3.2 

CC14 0.001 0.4 <0.01 1.0 0.7 0.4 0.7 1.0 

CC26 0.002 0.2 <0.01 4.0 1.1 4.5 0.4 < 1 

CC27 0.002 0.2 <0.01 4.5 1.1 2.2 0.4 < 1 

CC28 0.004 1.0 0.017 1.4 1.5 1.4 0.7 1.0 

CC29 0.005 7.6 0.019 0.5 1.4 1.6 0.6 < 1 

Evaporite Facies of Eagle Valley and South Park 

CC01 0.016 57.2 <0.01 110 2.8 7.6 0.9 1.7 

CC02 0.003 4.4 <0.01 1.3 2.0 < 0.1 2.1 1.6 

CC03 0.002 3.2 <0.01 1.4 1.5 1.2 3.2 < 1 

CC31 0.015 6.3 <0.01 5.9 1.0 0.3 0.4 < 1 

CC33 0.019 12.9 <0.01 7.9 1.0 3.4 0.4 < 1 

CC34 0.003 0.8 <0.01 2.4 1.4 3.5 2.7 < 1 

CC36 0.019 7.1 <0.01 18.1 2.2 5.2 1.8 1.2 

CC38 0.020 441 <0.01 16.8 3.4 15.3 0.7 1.0 

CC39 0.001 0.1 0.030 < 0.1 1.6 0.4 2.8 < 1 

CC40 0.002 0.06 0.011 1.2 1.4 4.2 1.1 < 1 

CC41 0.016 6.3 0.023 6.7 2.0 2.8 2.7 3.8 
Site Fe Mn P Li ug/L Sc ug/L Ti ug/L V ug/L Cr ug/L 

μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L 

Sangre De Cristo Formation in the Sangre de Cristo Range 

CC15 0.012 1.0 <0.01 0.6 0.8 0.5 0.4 < 1

CC16 0.002 1.2 0.013 1.0 1.2 0.5 1.0 < 1

CC17 0.016 0.7 <0.01 0.8 0.4 0.6 0.3 < 1

CC18 0.004 4.4 <0.01 1.1 0.4 1.1 0.2 < 1

CC19 <0.001 0.2 <0.01 1.1 0.4 1.0 0.2 < 1

CC20 <0.001 0.4 <0.01 1.6 1.1 0.3 0.4 < 1

CC21 0.001 0.2 <0.01 1.0 0.4 0.4 0.2 < 1

CC22 <0.001 < 0.01 <0.01 0.6 0.5 < 0.1 1.6 5.7

CC23 <0.001 0.07 <0.01 1.2 1.0 1.3 0.3 < 1

CC24 <0.001 0.4 <0.01 0.8 1.0 0.8 0.5 < 1

CC25 0.002 < 0.01 <0.01 3.4 1.4 < 0.1 3.8 14.0

Eby and Beaver Creeks 

CC32 0.024 1.1 <0.01 0.4 0.9 0.1 0.1 < 1

CC37 0.009 22.8 <0.01 18.1 1.9 1.2 1.5 1
Appendix 1. Chemical analyses of waters from areas underlain by Permian and Pennsylvanian rocks, western 

Colorado. (PPsc) Sangre de CristoFormation, (PPwm) Weber Sandstone and Maroon Formation, (Pee) 

Evaporitic Facies, (Pe) Eagle Valley Formation, (Pmbe) Evaporitic Facies, (Pm) Minturn Formation, (Pmb) 

Minturn and Belden Formations, (MDr) Missippian and Devonian rocks, and (PC) Precambirian rocks 

(Tweto, 1979). 

Site Co Ni Cu Zn Rb Sr Y Zr Nb Mo 

μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L 

Minturn and Belden Formations in the Redcliff Area 

CC05 0.04 0.8 0.63 0.7 0.54 81.0 0.04 < 0.05 < 0.02 0.62 

CC06 0.08 2.1 0.53 0.6 0.37 597 0.12 < 0.05 < 0.02 0.85 

CC07 0.05 1.2 < 0.5 < 0.5 0.31 98.4 0.03 < 0.05 0.03 1.29 

CC08 0.06 1.0 < 0.5 < 0.5 0.27 61.0 0.03 0.05 0.03 0.42 

CC09 0.05 1.1 < 0.5 < 0.5 0.32 85.4 0.02 < 0.05 0.03 0.31 

CC10 0.07 1.4 < 0.5 < 0.5 0.30 86.2 0.01 < 0.05 0.03 0.31 

CC11 0.04 0.9 < 0.5 < 0.5 0.35 52.6 0.03 < 0.05 0.02 < 0.2 

Minturn and Belden Formations in the Flat Tops Area 

CC43 0.10 2.9 0.57 0.6 0.50 1030 0.10 < 0.05 < 0.02 2.21 

CC44 0.09 2.5 0.50 < 0.5 0.33 1040 0.10 < 0.05 < 0.02 2.16 

CC45 0.11 1.6 < 0.5 < 0.5 0.57 53.6 0.03 < 0.05 < 0.02 0.42 

CC46 0.06 1.6 < 0.5 < 0.5 0.34 53.4 0.02 < 0.05 < 0.02 < 0.2 

CC47 0.09 2.0 < 0.5 < 0.5 0.77 98.3 0.02 < 0.05 < 0.02 0.50 

CC48 0.07 1.7 < 0.5 < 0.5 0.57 55.4 0.03 < 0.05 < 0.02 < 0.2 

CC49 0.07 1.6 < 0.5 < 0.5 0.29 67.6 0.07 < 0.05 < 0.02 < 0.2 

CC50 0.06 1.4 < 0.5 < 0.5 0.35 59.9 0.02 < 0.05 < 0.02 < 0.2 

Minturn and Belden Formations in the Sangre de Cristo Range 

CC13 0.04 1.0 < 0.5 18.6 0.23 198 0.01 < 0.05 < 0.02 0.53 

CC14 0.03 0.9 < 0.5 0.8 0.37 120 0.01 < 0.05 < 0.02 0.79 

CC26 0.07 2.3 0.50 0.6 0.90 1230 0.10 0.06 0.06 2.38 

CC27 0.09 2.6 0.53 0.5 0.64 1310 0.12 < 0.05 0.02 2.75 

CC28 0.09 2.2 0.86 0.7 0.73 506 0.13 < 0.05 < 0.02 1.80 

CC29 0.09 2.1 0.60 0.5 1.48 572 0.10 0.05 < 0.02 8.06 

Evaporite Facies of Eagle Valley and South Park 

CC01 0.30 6.0 1.7 2 8.43 3110 0.14 0.3 < 0.02 0.71 

CC02 0.08 1.6 2.2 123 0.23 363 0.03 < 0.05 < 0.02 0.46 

CC03 0.07 1.6 0.55 0.6 0.35 828 0.16 < 0.05 < 0.02 1.90 

CC31 0.06 1.1 1.4 0.9 0.64 229 0.05 0.06 < 0.02 0.74 

CC33 0.13 3.5 1.3 7.0 0.89 1280 0.11 0.05 < 0.02 1.71 

CC34 0.13 3.9 0.79 0.7 0.32 1690 0.11 < 0.05 < 0.02 3.25 

CC36 0.21 5.1 1.1 1 0.75 2670 0.11 0.2 < 0.02 6.86 

CC38 3.00 14.4 2.3 2.3 1.00 4720 0.13 0.2 < 0.02 8.62 

CC39 0.04 1.2 < 0.5 < 0.5 0.27 215 0.01 < 0.05 < 0.02 0.83 

CC40 0.14 4.5 0.77 1 0.38 1270 0.10 < 0.05 < 0.02 2.50 

CC41 0.22 4.2 0.91 0.8 0.59 1340 0.14 0.08 < 0.02 2.39 
Site Co Ni Cu Zn Rb Sr Y Zr Nb Mo 

μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L 

Sangre De Cristo Formation in the Sangre de Cristo Range 

CC15 0.03 0.3 0.62 1 0.42 36.4 0.09 0.06 < 0.02 0.47 

CC16 0.04 0.6 < 0.5 < 0.5 0.24 79.9 0.03 < 0.05 0.02 < 0.2 

CC17 0.03 0.6 0.52 < 0.5 0.23 86.7 0.03 < 0.05 < 0.02 < 0.2 

CC18 0.05 1.0 < 0.5 < 0.5 0.28 279 0.01 < 0.05 < 0.02 0.41 

CC19 0.04 1.0 < 0.5 < 0.5 0.26 259 0.01 < 0.05 < 0.02 0.30 

CC20 0.04 0.9 < 0.5 < 0.5 0.20 145 0.02 < 0.05 < 0.02 < 0.2 

CC21 0.03 0.7 0.54 < 0.5 0.42 86.5 0.03 < 0.05 < 0.02 < 0.2 

CC22 0.03 0.6 < 0.5 < 0.5 0.38 81.8 0.02 0.1 0.1 0.46 

CC23 0.03 0.8 < 0.5 < 0.5 0.52 132 0.01 < 0.05 0.04 < 0.2 

CC24 0.05 1.0 < 0.5 < 0.5 0.27 91.6 0.02 < 0.05 0.02 < 0.2 

CC25 0.04 1.2 < 0.5 < 0.5 0.53 364 0.08 0.1 0.1 1.38 

Eby and Beaver Creeks 

CC32 0.0 0.3 < 0.5 0.80 0.44 34.30 0.08 0.05 < 0.02 < 0.2 

CC37 0.13 3 0.6 0.5 0.54 1180 0.11 0.08 < 0.02 3.85 
Appendix 1. Chemical analyses of waters from areas underlain by Permian and Pennsylvanian rocks, western 

Colorado. (PPsc) Sangre de CristoFormation, (PPwm) Weber Sandstone and Maroon Formation, (Pee) 

Evaporitic Facies, (Pe) Eagle Valley Formation, (Pmbe) Evaporitic Facies, (Pm) Minturn Formation, (Pmb) 

Minturn and Belden Formations, (MDr) Missippian and Devonian rocks, and (PC) Precambirian rocks 

(Tweto, 1979). 

Site Sb Cs Ba La Ce Pr Nd Sm Eu Tb 

μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L 

Minturn and Belden Formations in the Redcliff Area 

CC05 < 0.1 < 0.01 167 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.02 < 0.005 

CC06 < 0.1 < 0.01 65.5 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.007 < 0.005 

CC07 0.1 < 0.01 73.6 < 0.01 < 0.01 < 0.01 0.01 < 0.01 0.008 < 0.005 

CC08 < 0.1 < 0.01 86.3 < 0.01 < 0.01 < 0.01 0.01 < 0.01 0.008 < 0.005 

CC09 < 0.1 < 0.01 66.0 < 0.01 < 0.01 < 0.01 0.01 < 0.01 0.008 < 0.005 

CC10 < 0.1 < 0.01 62.0 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.007 < 0.005 

CC11 < 0.1 < 0.01 85.8 0.01 < 0.01 < 0.01 0.02 < 0.01 0.01 < 0.005 

Minturn and Belden Formations in the Flat Tops Area 

CC43 < 0.1 < 0.01 60.4 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.006 < 0.005 

CC44 < 0.1 < 0.01 47.5 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.006 < 0.005 

CC45 < 0.1 < 0.01 34.6 0.01 0.03 < 0.01 0.01 < 0.01 0.007 < 0.005 

CC46 < 0.1 < 0.01 39.5 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 < 0.005 < 0.005 

CC47 < 0.1 < 0.01 76.4 < 0.01 0.01 < 0.01 < 0.01 < 0.01 0.01 < 0.005 

CC48 < 0.1 < 0.01 34.4 0.01 0.02 < 0.01 0.01 < 0.01 0.006 < 0.005 

CC49 < 0.1 < 0.01 37.8 0.03 0.02 < 0.01 0.03 < 0.01 0.007 < 0.005 

CC50 < 0.1 < 0.01 44.7 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.005 < 0.005 

Minturn and Belden Formations in the Sangre de Cristo Range 

CC13 < 0.1 < 0.01 46.9 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.006 < 0.005 

CC14 < 0.1 < 0.01 47.0 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.006 < 0.005 

CC26 < 0.1 < 0.01 39.6 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.006 < 0.005 

CC27 0.2 < 0.01 38.2 < 0.01 < 0.01 < 0.01 0.01 < 0.01 0.005 < 0.005 

CC28 < 0.1 < 0.01 39.6 < 0.01 0.02 < 0.01 0.01 < 0.01 0.005 < 0.005 

CC29 < 0.1 < 0.01 42.8 < 0.01 0.01 < 0.01 0.02 < 0.01 < 0.005 < 0.005 

Evaporite Facies of Eagle Valley and South Park 

CC01 < 0.1 < 0.01 71.6 < 0.01 0.02 < 0.01 0.02 < 0.01 0.009 < 0.005 

CC02 < 0.1 < 0.01 104 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.01 < 0.005 

CC03 < 0.1 < 0.01 40.1 0.02 0.05 < 0.01 0.02 < 0.01 0.007 < 0.005 

CC31 < 0.1 < 0.01 36.1 0.03 0.03 0.01 0.04 0.01 0.007 < 0.005 

CC33 < 0.1 < 0.01 53.4 0.02 0.03 < 0.01 0.03 < 0.01 0.007 < 0.005 

CC34 < 0.1 < 0.01 116 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.02 < 0.005 

CC36 0.1 < 0.01 55.3 < 0.01 0.01 < 0.01 < 0.01 < 0.01 0.007 < 0.005 

CC38 < 0.1 < 0.01 34.2 0.01 0.03 < 0.01 < 0.01 < 0.01 0.005 < 0.005 

CC39 < 0.1 < 0.01 72.5 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.007 < 0.005 

CC40 < 0.1 < 0.01 19.5 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.005 < 0.005 

CC41 < 0.1 < 0.01 92.7 0.01 0.03 < 0.01 0.02 < 0.01 0.01 < 0.005 
Site Sb Cs Ba La Ce Pr Nd Sm Eu Tb 

μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L 

Sangre De Cristo Formation in the Sangre de Cristo Range 

CC15 < 0.1 < 0.01 14.8 0.05 0.04 0.01 0.06 < 0.01 0.005 < 0.005 

CC16 < 0.1 < 0.01 64.2 0.01 0.01 < 0.01 0.01 < 0.01 0.007 < 0.005 

CC17 < 0.1 < 0.01 48.2 0.02 0.02 < 0.01 0.02 0.01 0.007 < 0.005 

CC18 < 0.1 < 0.01 25.8 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 < 0.005 < 0.005 

CC19 < 0.1 < 0.01 46.3 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.007 < 0.005 

CC20 < 0.1 < 0.01 180 < 0.01 < 0.01 < 0.01 0.01 < 0.01 0.02 < 0.005 

CC21 < 0.1 < 0.01 80.1 0.01 < 0.01 < 0.01 0.02 < 0.01 0.01 < 0.005 

CC22 0.1 < 0.01 43.5 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.006 < 0.005 

CC23 < 0.1 0.01 121 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.02 < 0.005 

CC24 < 0.1 < 0.01 136 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.01 < 0.005 

CC25 0.64 < 0.01 186 < 0.01 < 0.01 < 0.01 < 0.01 < 0.01 0.02 < 0.005 

Eby and Beaver Creeks 

CC32 < 0.1 < 0.01 20.40 0.11 0.04 0.03 0.1 0.02 0.01 < 0.005 

CC37 < 0.1 < 0.01 66.7 < 0.01 < 0.01 < 0.01 0.01 < 0.01 0.008 < 0.005 
Appendix 1. Chemical analyses of waters from areas underlain by Permian and Pennsylvanian rocks, western 

Colorado. (PPsc) Sangre de CristoFormation, (PPwm) Weber Sandstone and Maroon Formation, (Pee) 

Evaporitic Facies, (Pe) Eagle Valley Formation, (Pmbe) Evaporitic Facies, (Pm) Minturn Formation, (Pmb) 

Minturn and Belden Formations, (MDr) Missippian and Devonian rocks, and (PC) Precambirian rocks 

(Tweto, 1979). 

Site Gd Dy Ta W Pb Bi Th U 

μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L 

Minturn and Belden Formations in the Redcliff Area 

CC05 0.01 0.009 < 0.02 < 0.02 < 0.05 < 0.005 < 0.005 2.13 

CC06 < 0.005 < 0.005 < 0.02 < 0.02 < 0.05 < 0.005 < 0.005 1.18 

CC07 0.005 < 0.005 0.04 0.06 < 0.05 0.06 0.01 1.43 

CC08 0.005 < 0.005 0.04 0.06 < 0.05 0.02 0.01 1.04 

CC09 < 0.005 < 0.005 0.04 0.06 < 0.05 0.01 0.008 1.23 

CC10 < 0.005 < 0.005 0.03 0.05 < 0.05 0.008 0.008 1.43 

CC11 0.005 < 0.005 0.03 0.02 < 0.05 < 0.005 < 0.005 1.41 

Minturn and Belden Formations in the Flat Tops Area 

CC43 < 0.005 < 0.005 < 0.02 0.02 < 0.05 < 0.005 0.005 1.93 

CC44 < 0.005 < 0.005 < 0.02 < 0.02 < 0.05 < 0.005 < 0.005 2.40 

CC45 < 0.005 < 0.005 < 0.02 < 0.02 < 0.05 < 0.005 < 0.005 1.09 

CC46 < 0.005 < 0.005 < 0.02 < 0.02 < 0.05 < 0.005 < 0.005 0.49 

CC47 < 0.005 < 0.005 < 0.02 < 0.02 < 0.05 < 0.005 < 0.005 0.97 

CC48 < 0.005 < 0.005 < 0.02 < 0.02 < 0.05 < 0.005 < 0.005 0.36 

CC49 0.005 0.005 < 0.02 < 0.02 < 0.05 < 0.005 0.005 0.57 

CC50 < 0.005 < 0.005 < 0.02 < 0.02 < 0.05 < 0.005 < 0.005 0.38 

Minturn and Belden Formations in the Sangre de Cristo Range 

CC13 < 0.005 < 0.005 0.02 0.03 < 0.05 < 0.005 0.005 1.25 

CC14 < 0.005 < 0.005 0.03 0.04 < 0.05 < 0.005 < 0.005 1.19 

CC26 < 0.005 < 0.005 0.05 0.07 < 0.05 < 0.005 0.02 1.00 

CC27 < 0.005 < 0.005 0.05 0.07 < 0.05 0.05 0.03 1.26 

CC28 < 0.005 < 0.005 0.04 0.07 < 0.05 0.02 0.02 1.81 

CC29 < 0.005 < 0.005 0.03 0.08 < 0.05 0.009 0.03 1.24 

Evaporite Facies of Eagle Valley and South Park 

CC01 < 0.005 < 0.005 0.06 0.07 < 0.05 < 0.005 0.05 1.16 

CC02 < 0.005 < 0.005 < 0.02 < 0.02 0.1 < 0.005 < 0.005 1.69 

CC03 0.008 0.009 < 0.02 < 0.02 < 0.05 < 0.005 0.005 1.62 

CC31 0.008 0.007 < 0.02 0.04 < 0.05 < 0.005 0.007 0.37 

CC33 0.009 0.006 < 0.02 0.04 0.08 < 0.005 0.03 1.45 

CC34 < 0.005 < 0.005 < 0.02 < 0.02 < 0.05 < 0.005 0.02 1.93 

CC36 < 0.005 < 0.005 < 0.02 0.03 < 0.05 < 0.005 0.04 6.12 

CC38 < 0.005 < 0.005 < 0.02 0.03 < 0.05 < 0.005 0.14 4.57 

CC39 < 0.005 < 0.005 < 0.02 < 0.02 < 0.05 < 0.005 < 0.005 0.44 

CC40 < 0.005 < 0.005 < 0.02 < 0.02 < 0.05 < 0.005 0.008 1.04 

CC41 0.006 0.006 0.03 0.04 < 0.05 < 0.005 0.01 1.45 
Site Gd Dy Ta W Pb Bi Th U 

μg/L μg/L μg/L μg/L μg/L μg/L μg/L μg/L 

Sangre De Cristo Formation in the Sangre de Cristo Range 

CC15 0.02 0.01 0.03 0.03 < 0.05 < 0.005 0.01 0.03 

CC16 0.006 < 0.005 0.03 < 0.02 < 0.05 < 0.005 0.007 0.20 

CC17 0.007 0.005 0.02 0.02 < 0.05 < 0.005 0.006 0.32 

CC18 < 0.005 < 0.005 < 0.02 0.02 < 0.05 < 0.005 0.007 0.48 

CC19 < 0.005 < 0.005 < 0.02 < 0.02 < 0.05 < 0.005 < 0.005 0.28 

CC20 < 0.005 < 0.005 < 0.02 0.03 < 0.05 < 0.005 < 0.005 0.25 

CC21 < 0.005 < 0.005 < 0.02 < 0.02 < 0.05 < 0.005 < 0.005 0.43 

CC22 < 0.005 < 0.005 0.08 0.51 < 0.05 < 0.005 0.007 0.21 

CC23 < 0.005 < 0.005 0.03 0.05 < 0.05 < 0.005 < 0.005 0.62 

CC24 < 0.005 < 0.005 0.03 < 0.02 < 0.05 < 0.005 < 0.005 1.59 

CC25 < 0.005 < 0.005 0.09 0.44 < 0.05 < 0.005 < 0.005 1.94 

Eby and Beaver Creeks 

CC32 0.02 0.01 < 0.02 < 0.02 < 0.05 < 0.005 0.008 0.06 

CC37 < 0.005 < 0.005 < 0.02 < 0.02 < 0.05 < 0.005 0.009 2.42