Prepared in cooperation with the City of Boulder, Colorado 

STATE OF THE WATERSHED: 

WATER QUALITY OF BOULDER CREEK, COLORADO 

US. GEOLOGICAL.SURVEY CIRCULAR 1284 

U.S. Department of the Interior 

U.S. Geological Survey 

State of the Watershed: 

Water Quality of Boulder Creek, Colorado 

By Sheila F. Murphy 

Prepared in cooperation with the City of Boulder, Colorado 

U.S. Geological Survey Circular 1284 

U.S. Department of the Interior 

U.S. Geological Sunrey 
U.S. Department of the Interior 

Gale A. Norton, Secretary 

U.S. Geological Suwey 

P. Patrick Leahy, Acting Director 

U.S, Geological Survey, Reston, Virginia: 2006 

For sate by U.S. Geological Survey, Information Services 

Box 25286, Denver Federal Center 

Denver, CO 80225 

For more information about the USES and its products: 

Telephone: l-888-ASK-USGS 

World Wide Web: http:/lwww.usgs.govJ 

Any use of trade, product, or f~rm names In this publ~cation IS for descriptive purposes only and does not imply 

endorsement by the U.S. Government. 

Although this report is in the public domain, it contains copyrighted materials that ate noted in the text. 

Permission to reproduce those items must be secured from he individual copyrlght owners. 

Library of hngress Cataloging-in-Publication Data 

Murphy. Sheila F. 

State of the watershed : water qualiv of Boulder Creek, Colorado /by Sheila Murphy. 

p. cm. -(USGS Circular : 1284) 

Includes bibliographic references. 

1. Water quality -- Colorado -- Boulder Creek Watershed (Boulder and Weld Counties). I. Title. 

II. U.S. Geological Survey circular ; 1284. 

TD224.C7M87 2006 

363.739'420978863-4~22 

ISBN 1-411-30954-5 
iii 

Contents 

Welcome to the Boulder Creek Watershed .............................................................................................. 1 

Environmental Setting ................................................................................................................................... 2 

Hydrology ........................................................................................................................................................ 6 

How does water management affect the flow of Boulder Creek? ..................... ..................... 8 

How clean is the water in Boulder Creek? ................................................................................................ 9 

Water Quality of Boulder Creek from Top to Bottom .............................. .... ............................................ 12 

What fish species live in Boulder Creek? ................................................................................................ 20 

What is the quality of ground water in the Boulder Creek Watershed? ........... ......................... 21 

What was the quality of water in the Boulder Creek Watershed in the past? .................................. 22 

Timeline for the Boulder Creek Watershed .......................................................................................... 27 

How does water quality in the Boulder Creek Watershed compare to other 

Front Range watersheds and to watersheds nationwide? ..................................................... 28 

What will be the water-quality issues in the Boulder Creek Watershed in the future? .................. 29 

Summary ................................................................................................................................................... 30 

References .................................................................................................................................................... 31 

Acknowledgments ....................................................................................................................................... 34 

For more information ................................................................................................................................... 34 

Welcome to the Boulder Creek Watershed 

The Boulder Creek Watershed is approximately 1,160 square kilometers (447 square miles) in area and is located in the 

Front Range of the Colorado Rocky Mountains, east of the Continental Divide. The watershed includes all the land area that 

drains water into Boulder Creek. The watershed has great variation in geology, climate, and land cover. Tributaries of Boulder 

Creek include North, Middle, and South Boulder Creeks, Fourmile Creek, Coal Creek, and Rock Creek, along with several 

smaller streams, These streams generally flow from west to east. Boulder Creek empties into Saint Vrain Creek, which empties 

into the South Platte River. The water in Boulder Creek eventually reaches the Mississippi River and the Gulf of Mexico. The 

communities of Boulder, Louisville, Lafayew, Me, Superior, and Nederland am in the watershed, along with parts of Arvada, 

Broomfield, and Frederick In 2000, about 185,000 people lived in the Boulder Creek Watershed (U.S. Census Bureau, 2001). 

A reliable source of high-quality water is important for drinking-water supply, recreation, aquatic life, and agriculm. In 

the semiarid environment of the Colorado Front Range, water resources are limitad and waterways are subject to stress by com- peting uses. The population of the five largest communities in the watershed (Boulder, Lafayette, Louisville, Superior, and Erie) 

grew by 36 percent from 1990 to 2000, increasing demands on water resources. 'Ihis report, prepared by the U.S. Geological 

Survey in cwperation with the City of Boulder, presents the state of water quality in the Boulder Creek Watershed in 2005 and 

how it has changed over the past 160 years, and identifies potential future water-quality concerns. 

Boulder Creek Wmnh J (from Murphy and dm, #Ma1 
2 State of the Watershed: Water Quality of Boulder Creek, Colorado 

Environmental Setting 

The Boulder Creek Watershed lies within two physiographic provinces. The mountainous upper watershed is part of the 

Southern Rocky Mountains Province and is characetized by deep. steeply sloping valleys. The flatter, lower watershed is part of 

the Colorado Piedmont Section of the Great Plains Province and slopes gently to the northeast. The two regions differ substantially in geology, climate, and land cover. 

I 

Near the Continental Divide Urban corridor Agricuttural reach of Boulder Creek 

Physiography 

Elevations in the watershed range from 4,120 meters Creek. The great variation in topography produces five distinct 

(1 3,520 feet) at the Continental Divide to 1.480 meters (4,860 clhatid=ological zones: alpine, subdpine, montane, footfeet) at the confluence of Boulder Creek aud Saint Vrain hills, and plains. 

f 

EXPLANATION ' 

ELEVATION CLIMATIC 

WETEM) ZONE 

9,600- 4,200 ALPINE 

, 2,700- 3,600 BVBALPINE 

1 2,400 - 2,700 MONTANE 

1,600 - 2,400 FOOTHILL8 

I 

I 1,480 -1,WO PWN8 

Elewtlon and ollmatfcle~ologlcet xonoa (data fmm U.S. Geological Sunray, 20051; a few 

mesas arm included In the plalns climndc/acologlcal mnm deaph higher otauadons). 

\ J 
Environmental Setting 3 

Climate 

Temperatures vary widely across the climaticlmlogical as snow in the mountains during winter and spring. Melting of 

zones of the watershed., generally, temperature increases and snow produces high flows in Boulder Creek and its tributaries 

the difference between minimum and maximum temperatures in spring and summer. 

increases with decreasing elevation. Most precipitation falls 

r EXPUNAflON 

ANNUAL 

PREClPlTATION 

I t,MH).1,100 

I m 800-1,m 

C m7- 

-fOO 

m- - 

300.400 

Elblmdrd rvrragr annurl prrclpMon (braed on r model from 

Oaly and othrrr, 1994 for 16.mqwrr-kilometer grld call#), 

40 40 

30 V1 

0 

L -20 + -20 

AVERAGE MAXIMUM = 1 

MONTH MONTH 

I Air temperatures in the alpine and plains in 2000 (data from Niwot Ridge Long-Term Ecological 

Research Program, 2002, and National Oceanic and Atmospheric Administration, 2002). 
4 Stata of the Watershd Water Quality of Boulder Creek. Colorado 

Geology 

The upper watershed is underlain by 1 .&I .8 billionyear-old metamorphic and granitic bedrock, with deposits of 

gold, silver, tungsten. and other metals that were emplaced 

M0 million years ago. The lower watershed is underlain by 

65-300 million-yemld sedimentary rocks. includmg shale, 

sandstone, limestone, and coal-bearing deposits (Murphy and 

others, 2003). Mountain-building events that occurred about 

70 million years ago caused steeply dipping rock layers at 

the edge of the mountain front. Ridges and valleys reflect 

subsequent erosional processes. Metal and cod mining 

fueled settlement of the watershed in the 18608. Today, sand 

and gravel is mined along Boulder Creek, and oil and natural 

gas are extracted in the eastern part of the watershed. 

EXPLANATION 

GEOLOGY 

WATERNARY 

ALLUVIUM 

TERTIARY 

VOLCANIC 

1 TERTIARY 

SEDIMENTARY 

MESOZOIC 

SEDIMENTARY 

PRECAMBRIAN 

METAMORPHIC 

PRECAMBRIAN 

IGNEOUS 

WATER 

L Geology (from Tweto, 1979, and Green, 19921 

Land Cover 

The upper watershed consists primarily of forest, 

shrubs, and alpine tundra The lower waded consists 

of grassland, agricultural land, and urbaddeveloped land. 

Agricultud lands primarily consist of pasture and fields 

of alfalfa, wheat, corn, and barley. Urbanized land of the 

plains and foothills has increased substantially in the past 

30 years in areas that were previously forest, grassland, or 

agricultural land. Reservoirs have increased in number and 

size, and sand and gravel quarries along Boulder Creek 

have filled with water and formed ponds. 

Upper watershed 
Envimnmsntal Setting 5 

EXPLANATION 

!AMD COVER 

URMNOEELOP€D 

GRASSLAN~ OR TUN 

Land cover in 1942 (data from USGS, M03). Relative percentages of land cover 

992 (data from USGS, 20031. 

ExPLANCrrlON 

AND COVER 

I URBANIDEVELOPE 

QRAsSlAND 

I K~RESTISHUUBLAND I- = AQRICULTURE 

WATER 

A 

I 10 KlLOMETERS ' 

Land cover of the plains and foothills over time (data from USGS, 1998). I 
State of the Watershed: Water Quality of Boulder Creek, Colorado 

Hydrology 

Streamflow in Boulder Creek originates primarily as snowmelt near the Continental Divide, so discharge varies seasonally 

and annually depending on snowpack depth and air temperature. Low-flow conditions occur from October to March; highflow conditions occur from May to July and usually peak in June. Discharge (flow rate) of Boulder Creek and its tributaries is 

recorded by several streamflow-gaging stations. Stream discharge data are important in allocating water rights, estimating flood 

potential, and evaluating long-term changes in hydrology and water quality. The Ordell streamflow-gaging station, located on 

Boulder Creek in Boulder Canyon, has been recording discharge since 19%. 

Orodell streamflow-gaging station on Boulder Creek 

1.m $8 

d 0, 3% 

800 a UY k 

LU 

400 5 

200 d 0 

2 2 

0 sz 

Discharge of Boulder Creek at the Orodell streadow-gaging station, 1975-2004 

[data from USGS, 2004, and Colorado Division of Water Resources, M051 
Boulder Creek and its tributaries are part of a complex 

water-management system. Diversions remove water from 

skams for municipal, industrial, and agricultural use. Reservoirs store water for a reliable year-round supply. Water is 

brought into and out of the watershed by transbasin diversions. Wastewater laant plants contribute trated effluent 

that can account for a substantial portion of flow in streams 

in the lower watershed during low-flow conditions. 'q 

*j . ; 

EXPLANMWN 

- -..*-.. STREAM 

- DrrCH 

PlPEllNE 

m LAKE OR RESERVOIR 

WATER TREATMENT PLANT 

WASTEWATER TREATMENT W 

aoULDERWON 

HYDROELECI'RIC PIANT AND 

ORWELL 8tREAMFLCWY-CAOlM 

STATION 
State of the Watershed: Water Puality of Boulder Creek, Colorado 

How does water management affect the flow of Boulder Creek? 

The many water diversions and returns in the watershed lead to complex temporal and spatial variations in discharge, 

affecting both the quantity and quality of water in Boulder Creek and its tributaries. 

EXPWrn 

-?ln~~CWR 

10 KtLOMITLII8 

adon dnea lOlR Boulder now €,dinatad dl#chargm In thu mMhd durlng hlgh tkv Nun. 2000, top) arid low I( 

flow (Octobrr 2W0, bottom) Iwldth of blua ltnm npnwntl dltchargm; do- from 

Murphy and othwn, 2OM, and Colorado Olvl8lon of Wmbr Rmnourcma, 
How clean is the water in Boulder Creek? 9 

How clean is the water in Boulder Creek? 

The answer to this question depends on what one means by "clean." Water that is considered good quality for aquatic life 

may not be considered suitable for human consumption, and vice versa. Water that is esthetically appealing may contain 

invisible water contaminants. One way to assess water quality is to compare it to established standards. 

Water-quality standards 

The Federal Clem Water Act requires States to establish water-quality standards, which are approved by the U.S. Environmental Protection Agency (USEPA). Standards have three main components: designated use classXcations, water-quality 

criteria, and policies to protect against degradation of water quality. 

Designated uses are human and ecological uses that are officially recognized and protected. Colorado's designated use 

categories are: 

Recreation: 

Chs 1 - hhmy Contmt: Waters suitable for recreational activities when ingestion of water is likely, such as swimming, 

kayaking, and tubing. There are two subcategories: Class 1A (existing use) and Class 1B (potential use). 

CEass 2 - Secomhy Contact: Waters not suitable for primary contact, but suitable for recreational uses such as wading and 

fishing. 

Agriculture: 

Waters suitable for crop irrigation and for livestock drinking water. 

Aquatic Life: 

Class 1: Waters capable of sustaining a wide variety of aquatic life, including sensitive species. There are two subcategories: 

cold water and warm water. 

Clrrss 2: Waters not capable of sustaining a wide variety of cold-water or warm-water aquatic life, including sensitive species, 

due to physical habitat, water flows. or uncorre.ct&Ie water-quality conditions. 

Domestic Water Supply: 

Surface waters suitable for drinking-water supplies. After standard treament, these waters will meet Coldo drinkingwater regulations. 

(Complete versions of Colomdo standQrds are available from the Colorado Depamant of Public Health and Environment 

(CDPHE; 2005a) 
10 State of the Watershed: Water Quality of Boulder Creek, Colorado 

Surface waters within a watershed are divided into segments, which are then assigned designated uses based on how 

the waters are currently used and what uses are desired for the 

future. Several designated uses have been applied to waters 

in the Boulder Creek Watershed. All of the waters have been 

classifd for recreation 1A and agricultural use, and dl except 

for parts of Coal Creek have been classified for domestic water 

supply (CDPHE, 2005b). Aquatic-life classifications vary, 

depending on water temperature and discharge. 

WatePquality criteria are descriptions of the chemical, 

physical, and biological conditions necessary to achieve and 

protect a water body's designated uses. For waters with multiple designations, the criteria must support the most sensitive 

use (CDPHE, 2005a). There are both narrative and numerical 

criteria. Narrative criteria describe waterquality goals and 

provide protection against contarninants that do not have specific numerical standards. Numerical standards set the acceptable concentrations of specific contaminants in streams, lakes, 

and reservoirs. Water-quality variables for which criteria exist 

include physical and biological constituents (such as dissolved 

oxygen and fecal coliform), inorganic constituents (such as 

ammonia and chloride), and metals (such as arsenic and lead). 

Antidegradation polici~ are used to protect water 

quality. Colorado provides three levels of provisions: 

outstanding waters, for which no degradation is allowed; 

use-protected waters, for which degradation is allowed so 

long as water-quality standards are still met; and reviewable 

waters, for which degradation is allowed so long as no reasonable alteratives are available and water-quality standards 

are still met (Colorado Foundation for Water Education, 

2003). In the Boulder Creek Watershed, all of the tributaries within the Indian Peaks Wilderness Area are designated 

as outstanding waters. In general, Boulder Creek and other 

tributaries in the mountains are reviewable waters, while 

surface waters on the plains are mostly use-protected waters 

(CDPHE, 2005b). 

f EXPLANATION \ 

WAlERmY WATERWKIPRY WATER WPRY 

mT1QN 1A -nu4 1A RECREATION 1A 

MRICULTWIE mlURE AQRWLTURE 

~~uFEcoto1 mlX LIFE eQLD2 ANATE URWARM 1 

I -MIA WATERSVPPLY 

AaRICULm mumnm mrn 1A 

MUATK; UA WAFkt 1 kMUTlGUFEWARM2 -TWIE 

AMMnC UFE WM 2 

0 - 10 KJLOMElERS 

Water-quali classifications in the Boulder Creek Watgnhed (data from CDPHE, 2005bJ. J 
. , How clean is the water in Boulder Creek? 11 

Water-quality assessment 

States are required by section 305@) of the Federal 

Clean Water Act to assess and report on the quality of the 

State's waters to Congress though the USEPA. Section 

305('b) reports describe the ways a State measures water 

quality, the quality of water hadies in the State, and pollution-control programs. The State of Colorado 305@) report 

is available from the CDPHE (2005c, d), 

When credible data on the water quality of a stream or 

lake indicate that a standard is nat met, the State proposes 

that the st~m segment be placed on a list of impaired segments, called the "303(d) list." The Colorado Water Qualit: 

Conlml Commission has a public hearing to consider 

recommendations and adopts Colorado's 303(d) Iis 

State regulation. The USEPA accepts the 303(d) lis, .,, 

the State or can list additional segments. The 303(d) list 

identifies the component(s) (such as nitrate, lead. or sediment) that is (we) causing water-quality concerns for that 

water body. Some stream segments in the Boulder Creek 

Watershed have been on the 303(d) list for ammonia ad 

E. coli (CDPHE, 2005c, d). 

Tbe State is required to prioritize water bodies on the 

303(d) list on the basis of the severity of impairment and 

other factors. It will then determine the causes of the waterquality concern and allocate responsibility for the impairment. This analysis is called the Total Maximum Daily 

Load (TMDL) process. The State of Colorado also i&t 

fies water bodies where there is reason to suspect waterquality impairment, but uncertainty exists about data quality 

or the cause of impairment. These waters are placed on the 

Monitoring and Evaluation W&E) List (CDPHE, 2M35c, d). 

Some stream segments in the Boulder Creek Watershed have 

been on the M&E list for aquatic life, E. coli, selenium, and 

cbromium VI. 

m _"T - -. 

Monitoring water quality of Boulder Creek 

TMDLmnpkMCmronU 

Onaaa(d)lUktEarr:rUDL 

OnM&EUrl*-m 

10 KILOMETERS 

Sepmenta not meetlnu designated us88 In the Bouldw Creek Wwnhed in XM 

Idam from CDPHE, 2006~1, 
12 State of the Watershed: Water halily of Boulder Creek, Colorado 

Water Quality of Boulder Creek from Top to Bottom 

Water quality in the Boulder Creek Watershed varies substanMly. In general, water quality is best in the high-elevation 

headwaters, where human activity is limited and there are few contaminant sources. Water quality declines downstream as 

diversions remove water from streams. population density increases, and there are more potential contaminant sources. In lower 

Boulder Creek, several factors a&ct water quality, including wastewater, urbanization, and agriculture. 

Headwaters and mountains 

The headwaters of the Boulder Creek Watershed originateprimarilyfromsnawmeltandgroundwaterththas 

flawed fhm@ dativeIy mtive hhck and soil. Therefore, these waters typically have very low mnmwations of 

dissolved sulids, dkdhity, and nutrients compared to downstrewn waters (Murphy aad others, 2003, chapters 3,4, and 8; 

Verplanck and others, 2003). Surface waters gcdy . 

have near-neutral pH due^, and dismlvd oxygen is at 

or near mucation. The City of Boulder wms a 30-km2 

(12 d) pmtmted watershed proptay in the headwaters of 

North Boulder Creek (see map w page 1); public entry is 

probibited to protect tbis bigh-quality wrtta source. Much of 

the headwaters of Middle Boulder Creek are within the Indian 

Peaks Wddmms Area, where motorized vehicles are not permitted. We direct human disturtace is limited, the headwaters are within he "airshed" of tbe hver melmpolitan area, 

where d-lid powerplants, autom~, md agricultural 

0.0001~~~~~'~~~~ 

70605040302010 0 

DISTANCE UPSTREAM FROM 

SAINT VRAlN CONFLUENCE, IN KILOMETERS 

EXPLANATION 

+ BWDER CREEK. JUNE 20W 

INFLOW, JUNE 2000 

+-BOULDER CREEK, OCTOBER 20W 

INFLOW, OCTOBER 2000 

Mercury concentrations in Middle Boulder CreeWBoulder 

Creek and major inflows. June and Octobar MOO, 

compared to USEPA drinking-water standard (note 

logarithmic scale; from Murphy and others, 2003, chapter 4; 

USEPA, U.S. Environmental Protection Agency). 

- 

Headwaters of North Boulder Creek {Arapaho Glacier at far left) 

activities reh contaminants (such as sulfate and nitrate) to 

the atmoqhere. Thew contaminants are carried in the atmosphm to the headwaters area, and retumed to the Eaah in 

rain and snow. Depition of nitrate and sulfate, even in low 

mncenhations, may decrease the pH of the poorly buffed 

headwaters, causing changes in aquatic ecosystems (Williams and Tomessen, 2000). Nitrate also can act as a fertilizer, 

changing the growth rates of plants. 

The upper watershed was mined intensively in the past 

for gold, silver, tungsten, and other metals. Mining can sect 

water quality when sulfide minerals in waste mck and tailings interrtct with water and oxygen to produce sulfuric acid, 

which leaches metals from rmk and increases metal toxicity 

to aquatic organisms, The ore dqmsits in the Boulder Cnxk 

Watershed udy contain small amounts of sulfides, so runoff 

fkom old mines and tailings piles is typically not acidic or 

metal-rich. Metal concentrations in North Boulder and Middle 

Boulder creeks, such as mercury and lead, are usually low 

(Murphy and others. 2003, chapter 4). Some tributaries of 

South Boulder Creek are acidic and have elevated metal concenlrations, but flow in these tributaries is tm small to have 

a substantial ehzt on he main stern of South Bmlder Creek 

(Asher-Bolinder, 1995; Colorado Riverwatch. 2001). 
Barker Reservoir, on Middle Boulder Cre=ek downstream 

from the town of Nederland, stores as much as 14,426,000 m3 

(1 1,700 acre-feet) of water and provides up to 40 percent of 

the city of Boulder's drinking-water supply (City of Boulder, 

2002). The reservoir is usually W during spring runoff and 

then &awn off gradually until the next spring. The degree of 

drawdown varies from year to year depending on water ailWater Quality of Boulder Creek from Top to Bottoln 13 

ability and demand. Barker Reservoir generally has nearneutral pH and very low dissolved and suspended solids, 

ranging hm 15 to 40 mglL and hm 0 to 4 mglL, respectively (City of Boulder, unpub. data, 2004). Dissolved oxygen 

(DO) concentrations near the surface of the reservoir are 

typically near saturation because of photosynthesis and contact 

with the acmosphe~. The DO concentrations at the bottom of 

the reservoir are lower than near the top, reaching their lowest 

pt in late summer when the reservoir becomes stratified and 

the bottom waters do not mix with surface waters. Low DO 

can cause release of manganese, iron, and other metals horn Barker Reservoir 

bottom sediments into the water, which can cause problems 

for drinking-water treatment. 

120 

Nutrients, such as nitrogen and phosphorus, increase 

rates of plant growth. This increases be mount of organic 

matter produced and consumed and can contribute to the 

decline in DO at the bottom of a reservoir. Nederland's 

Wastewater Treatment Plant (WWP), an aerated lagoon 

facility, discharges up to 0.0083 m3/s (1 89,000 gallwslday) 

of treated wastewater to Barker Reservoir (USEPA, 2005). 

The is required by a permit hm CDPHE to meet 

certain water-quality standards, such as concentmtions of 

suspended solids, oil and grease, and ammonk Tbe 

Nederland WWTP contributes less than 1 ~nt of the 

total flow into the reservoir but contributes about 

66 percent of the phosphorus and 40 percent of the inor- ganic nitrogen entering the reservoir (City of Boulder, 

2002). In addition, homes using individual sewage disposal 

systems (ISDSs) are situated on both the north ;md south 

sides of the reservoir (mynn and Barber, 2000). Mdfunctioning ISDSs can be a source of nitrate, phosphorus, path* 

gens, and other constituents to ground water and surface 

water. 

. , 

! watershed are available from the Boulder Area 

Sustainabrlity Information NWo$ (13A,SmQWeb 1 

site, www.BASIN.org . . : -:.A; >, F ;,: 

\ 

z" A00 is 80 

z so sf6 

z L 40. 3z 

G M. 

O 0 

*. +.. m. 

A A A f 

A 

4 A, 

,,..,,-.. A* 

2001 20M 2003 

EXPLANATION 

BARKER RESERVOIR, TOP 

A BARKER RESERVOIR, WHOM 

Dissolved oxygen saturation in Barker Reservoir (data 

from Ci of Boulder; reservoir is not sampled November-May 

due to ice cover). 

/ 
I4 State of the Waterrhed: Water Ouality of Boulder Creek, Colorado 

Downsweam from Barker Moir and Lakewood Res- ervoir (located on North Boulder Creek and used by the City 

of Boulder to store water; see location map on page I), flow 

in Middle Boulder, North Boulder, and Boulder Creeks can 

be very low during parts of the year due to divewiws. These 

s- have near-neukal pH valus and DO concentrations 

near sabration (Murphy and Waterman, 2005). Dissolved 

and suspended solids are generally very low, ranging bm 20 

to tOO mg/L and from 0 to 10 mg/L, respectively. However, 

runoff from Highway 119, which parallels Middle Boulder and 

Bolllder Creeks, is a potential source of &ent, automobile fluids, road salts, and debris, and ISDSs in the region are 

potential sources of bacteria, nutrients, and consumer products 

to ground water and surface water. Historical mining sites also 

are potential sources of mtarninants; slightly elevated levels 

of dissolved solids have been detected in Fourmile Creek. 

which was once at the heart of gold-mining activity in the 

watershed (Murphy and others, 2003, chapter 4). 

Boulder Creek in Boulder Canyon 

I,. 

Abandoned mines and mill near Fourmile Creek 
Urban 

After water in Boulder Creek and its tributaries leaw 

the mountains, temperature, pH, and dissolved solids 

increase due lo natural and human-related factors. The 

underlying geology transitions from igneous and metamorphic mks to more easily eroded sedimentary rocks, 

increasing dissoIved-solids concenwations. Potential 

contaminant sources increase. Much of the water in South 

Boulder and Boulder Creeks is diverted in this area, leaving 

less water for dilution. 

Areas of urban development contain many impmious 

surfaces, such as streets, parking lots, sidew-, and roofs. 

Rain and snow cannot percolate into the ground, so large 

volumes of water enter streams rapidly. This can ede 

banks, damage stream-side vegetation, and widen stream 

channels. Also, contaminants from human activities settle 

and remain on impervious surfaces until a storm washes 

them, untreated, into nearby storm drains and then into 

waterways. Common contaminants in urban areas include 

oil, grease, metals, and road salt from Innsportation, sediment from construction, and nutrients and pesticides from 

landscaping. Paulson (1994) found that the metals arsenic, 

lead, and copper were highest in Boulder Creek during 

large storms. 

\ 

2003 20W 5 

YEAR 

EXPLANATION 

€BEN G. FINE PARK 

CPlTRAlPAuK 

CdlsOM STREET 

30TH STREET 

- RECREATlON 1A CRlTERlON gri I(ILOYICCBIC 

Geometric means of E. coli concentrations in Boulder Creek 

within the Ci of Boulder, M03-2005, and CDPHE recreation 1A 

criirion (dah from Ci of Boulder; N, number of samples; 

criierion based on a geometric mean of representative samples). 

Water Quality of Boulder Creek from Top to Bottom 15 

Recreation on Boulder Creek 

Is it rrde to swim in BuuMer Creek? 

Swimming in my water body imfoIvcs some degree of 

risk. During snowmelt runoff, Bdder Creek discharge 

can be dangerously high; values over 30 m31s 

(1,050 ft31s) have been recorded (USGS, 2004). All of 

the waters in the Boulder Creek Watershed are classified 

as recreation class lA, which hclh swhnhg, 

kayaling , and tubing (CDPHE, 2005b). Waterquality 

criteria for this classification include dissolved oxygen 

(DO), pH, fecal coliform, and Escherichla coli (E. cdi). 

DOandpHinsurfaccwstcrainthewatemkdart 

usually within the criteria. Parts of Boulder and Cod 

Creeks were included on the State of Colmdo's 20W 

list of water-quality-impaired streams {the 303[d] list) 

because of high levels of E. coli (CDW 2005~). 

E. coli and fecal coliform by themselves usually do not 

caw disease; they are used as indicators, which mtans 

they may indicate the presence of other disease-cauning 

microbes, These microbes are typically pmmt in such 

small amounts that they are difficult and expensive to 

detect but may cause hepatitis, gastmmkritis, md 

dysentery. Potential sources of E. coli are human 

(from instrearn recreation, leaky sanitary wer lines, 

and failing septic systems) and animal (raccwns in 

storm drains, pet waste dong the creek, waterfowl). 

Hundreds of people swim in Boolder Creek each year; 

Boulder County Public Health has herd no reports of 

serious waterborne illness from this use (written 

commun., 2005). To minimize contact with ba& 

the USEFA recommends avoiding swimming after a 

heavy rain, near stormdrain outlets, and in areas with 

trash or oil slicks in the water (USEPA, 1997). 
16 State of the Watershed: Water Quality of Boulder Creek, Colorado 

Lower Boulder Creek 

East of the city of Boulder, the Boulder WWTP is permitted to discharge as much as 77,600 m3 (20.5 million gallons) 

per day of treated wastewater to Boulder Creek (USEPA, I 

2005). 'Zht wastewater is treated using a trickling 6lterIsolids 

contact and nierification process. The amount of wastewater 

discharged varies over 24 hours, depending on water usage 

within the city of Boulder. The WWTP is required by a permit 

from CDPHE to meet certain water-quality standards. However, the WWTP effluent does cause a substantial change in 

the water quality of Boulder Creek. The effluent contains 

higher concentrations of dissolved solids and nutrients than 

Boulder Creek, so these constituents increase downstream 

from the WWTP (Murphy and Watamm, 2005). ConcentraI tions of suspended solids and fecal coliform in the effluent 

ate often lower than concentrations in Boulder Creek (due to 

permit requirements), so concentrations of these constituents 

often decrease downstream from the WWTP. 

Maln stem 

EXPLANATION 

EmnENEDkMIN-C ACID (EDTA) 

TOTAL NONYLPHaYaL~fEB WPEC) 

Concentrations of ehylenediaminetetraacetic acid (EOTA) and 

nonylphenolethoxycarboxylates (NPEC) in Boulder Creek and 

inflows, October 2000 (Murphy and others, 2003, chapter 5). 

Discharge point for the Boulder Wastewater Treatment Plant 

Studies of Boulder Creek downstream from the Boulder 

WWTP have detected trace organic wastewater compounds 

such as steroids, hormones, prescription and nonprescription 

drugs, surfactants, and pesticides (Murphy and others, 2003, 

chapters 5 and 6: Barber and others, 2006). Recent technological advances have allowed the detection of these compounds 

at very low levels; some of these compounds were detected 

at only a few parts per tilion. WWTPs are not required by 

law to remove these compounds, and their environmental and 

public health sidcance is not well undersW. The most 

abundant wastewater compounds detected in 2000 were ethylenediamincktrmcetic acid (EDTA), a metal complexing agent 

found in shampoo, mayonnaise, and vitamins, and nonylphenolethoxycarboxylates (NPEC), breakdown prducts from surfactants, which are components of detergents. Concentrations 

of orgamic wastewater compounds were highest in Boulder 

Creek directly downstream from the Boulder WWTP and in 

Coal Creek; concenmtions deaeased downstxam. In addition to organic wastewater compounds, the rare earth element 

gadolinium was found to be enriched in the Boulder WWTP 

effluent and Boulder Creek downstream from the Boulder 

WWTP (Murphy and others, 2003, chapter 4; Vcrplmck and 

others, 2005). Gadolinium has several industrial and mtdical 

uses. Because of its magnetic pmpdes, gadolinium is used 

as a contrasting agent in magnetic resonance imaging m). 

Organic gadolinium complexes are extmnely stable in the 

human body and in the environment; because of this stability, 

they are not easily moved during wastewater treatment or 

instream processes (Bau and Dulski, 19%). 
Water Quality of Boulder Creek from Top ta Bottom 17 

Water quality of Boulder Creek downstream from the 

Boulder WWTP is affected by a complex combination of 

sources and processes, The degree of effects from the Boulder 

WWTP on Boulder Creek depends on the ratio of wastewater 

emuent to background streamflow. Wastewater effluent ha a 

gmiter effect on water quality when background streadow in 

-Boulder Creek is low. During high-flow conditions, snowmelt 

runoff provides dilution for dissolved constituents. Therefore, 

concentrations of dissolved solids, nitrogen, and phosphorus 

in Boulder Creek downsmam from the WWP are typically 

lowest during late spg and early surnmer (Murphy and 

Watennan, 2005). 

Several diversions downstream from the WWTP remove 

tt substantial amount of water bm Boulder Creek. During 

some times of the year, the creek is virtually dry in places. 

These diversions remove much of the wastewater chemical 

load hm the creek. The creek gains water from agricultural 

irrigation return flows, tributaries, and ground water. These 

inflows provide dilution for nutrients, metals, and wastewater compounds but can increase some ions, such as sodium, 

magnesium, and sulfate (Murphy and others, 2003, chapter 

4). Nitrogen (nitrate, nitrite, ammonia, and organic nitrogen) 

and phosphorus also are removed from the water by vegetation 

uptake, sorption to sedimnt and organic matter, and bacterial processes. The level of ammonia concentrations that the 

Boulder WWTP is permitted to discharge varies throughout 

the year, and typically is highest bm November to March and 

lowest in June (City of Boulder, written comrnun., 2005). 

is!=). Z 349; 5: $$i$ 

1998 1999 2000 2001 2002 

Discharge and dissolved-solids concentrations in 

Boulder Creek immediately downsbeam from the 

Boulder WWTP (Data from USGS, 2004 and Cii of 

Boulder, unpub., MWb L 

= W-r - T

Ammonia and nitrate + nitrite concanbatlons in Boulder Creek, Nl1 (C@ of BwMer data] 
18 State of the Watershed: Water [luality of Boulder Creek, Colorado 

HOURS SINCE MIDNIGHT 

oll.l.l.l.'hl.lJ 

4 8 12 16 20 24 28 

HOURS SlNCE MIDNIGHT 

pH and dissolved oxygen over 24 hours in Boulder Creek 

13 kilometers downstream from the Boulder WWTP (data 

from Aquatic and Wetland Consultants, 1987). 

Much of lower Boulder Creek has been channelized and 

has little riparian vegetation to provide shade, so waters can 

reach temperatures as high as 30 degrees Celsius in summer 

months (Murphy and Waterman, 2005). Direct sunlight on the 

shallow, slow-moving, nutrient-rich water leads to acceleratd 

algal growth and high rates of photosynthesis. 

The high rate of photosynthesis during daylight hours 

prduces oxygen and consumes carbon dioxide, causing pH 

and DO to increase during the day. Respiration and decomposition, which occur 24 hours a day, consume oxygen and 

produce chn dioxide, causing lower pH values and DO concentrations at night. Over a 24-hour perid DO and pH have 

fluctuated as much as 12 mg/L and 2.1 pH units, respectively 

(Aquatic and Wetland Consultants, 1987). 

Boulder Creek near Highway 287 

In water with high pH and temperature values, ammonia takes the form of un-ionized ammonia, which is toxic to 

fish. Boulder Creek from South Boulder Creek to Saint Vrain 

Creek was included in Colorado's 303(d) list of impaired 

waters in 1W2 because of un-ionid ammonia (CDFHE, 

2005c, d). The City of Boulder attempted to improve water 

quality by restoring streambank stability, planting vegetation, 

and deepening channels, but high un-ionized ammonia concentrations continued, In 2003, a TMDL analysis quantified 

the amount of ammonia that can be discharged to Boulder 

Creek without exceeding standards. The analysis was used 

to assign allowable contaminant loads among ammonia 

bchargers (CDPHE, 2005e). Some WWTPs in the watershed, includmg the Boulder and Lafayette WWTPs, have 

been or will be upgraded to deamse the amount of ammonia 

discharged (Floyd Bebler, City of Boulder, written cornmun., 

2005; Douglas Short, City of Lafayette, oral cornmun., 2005). 

her Boulder Ditch near diversion from Boulder Creek 
Water Quality of Boulder Creek from Top to Bo&m 19 

Coal Creek merges with Boulder Creek hut 13 krn 

(8 mi) downstream from the Boulder WWTP. Coal Creek 

receives wastewater effluent from Erie, Lafayette, Louisville, 

and Superior WWTPs, which are permined to discharge a 

total of 40,882 m3 (10.8 million gallons) per day of effluent 

to Cod Creek or its tributary, ~&k creek (USEPA, 2005). 

Because the natural flow of Coal Creek is very small, the 

creek is composed almost entirely of wastewater effluent when 

it enters Boulder Creek. Therefore, concentrations of dissolved 

solids, nutrients, and organic contarninants in Caal Creek often 

are elevated relative to Boulder Creek and cause an increase 

in these contaminants in Boulder Creek (Murphy and others, 

2003, chaptas 3,4, and 5; Murphy and Waterman, 2005). 

Coal Cre& also may be affected by agricultural return flows. 

1 Coal Creek near lhyette 

her Boulder Creek flows through what has historically been an agriculturally dombkd area. About 7,890 

Hogmm (17,400 pounds) of pesticides (active in@- 

ent) were applied to agricultural land in Boulder County in 

1997 (Murphy and othm, 2003, chapter 6). Samples fmm 

Boulder Creek were analyzed for 84 pesticides in June and 

October 2000. Seven pesticides, including diazinon and 

atmine, were detected at one or both of the sampling l a - 

tions w lower Boulder Cmk (upstream fmm Cod Creek 

and upstream from Saint Vmh Creek). Agricultmal hds in 

the watershed have rapidly been comerted to urban areas in 

the past decade, one-third (202 square Idomekm, or 50,000 

anes)ofmCfnmlandinBodderCauntyw.s~~~to 

nonagricultural uses between 1992 and 2002 (U.S. DepartSunflowers near lower Boulder Creek menkf Agriculture, 2005). 

Conaftuetlon of new housing development nror Erie 
20 State of the Watershed Water Quality of Boulder Creek, Colorado 

What fish species live in Boulder Creek? 

and annually. Mountain smams are cold year-round, flow 

rapidly and turbulently, are low in nutrients, and have little 

or no aquatic shore vegetation (Ellis, 19 14). Plains streams 

are slower moving and subjected to intense sunlight, causing 

temperature, dissolved oxygen, and pH to vary drastically, parlow number of native fish species able to survive in the watershed (Fausch and Bestgen, 19%). Humans have substantially 

altered the nd hydrologic regime by diverting water from 

I 

titularly in late summer. These conditions led to a relatively Greenback cutthroat trout {courtesy Colorado Division of Wildlife) 

streams and building reservoirs, straightening stream channels, 

decreasing flow during high-flow periods, increasing flow during low-flow periods, and causing daily and hourly flow variations. In addition, nutrient loading is higher due to wastewater 

effluent, habitat has been fragmented, and non-native fish have 

been introduced. 

Much of lower Boulder Creek was channelized for flwd 

control. Channelization removes pools and riffles, which are 

important habitat for fish. In the 1980s the City of Boulder 

restored much of Boulder Creek within the city for recreation, 

esthetics, and fish habitat. About 75 fish habitat structures 

were built as part of this project, the majority being boulder 

drops with excavated pools (Steinberger and Wohl, 2003). 

Banks were stabilized, and riparian areas were revegetated. 

About 50 fish species, of which about 18 are non-native, 

now inhabit the South Platte River Watershed (Fausch and 

Bestgen, 1996). Introduced species usually fare best in manmade reservoirs; in streams, they generally are not successful 

because they must compete with species adapted to the watershed (Bluestein and Hendricks, 1974) and fluctuating hydrologic conditions. Non-native trout are an exception. Rainbow 

bout (Salmo gaiheri), brown trout (Salmo trutta), and brook 

trout (Salvelinus fontinalis) were stocked in Boulder Creek 

New Zealand rnudsnail 

(left, approximate size; 

right, magnified; courtesy 

White sucker [courtesy Colorado Division of Wildlife) 

soon after settlement and are now the principal fish species in 

the mountain streams of the watershed and within the city of 

Boulder (Thorne Ecological Institute, 1972). These fish outcompete the native greenback cutthroat trout (Oncorhymhm 

clarki stomias), a federally listed threatened species. In 

lower Boulder Creek, native white suckers (Catostomus 

commersoni) and fathead minnows (Pimephules pmmehs), 

along with non-native common carp (Cyprinlrs carpio), are the 

most abundant species downstream from the Boulder WWTP 

(Windell and Rink, 1987). These fish tolerate extreme variations of temperature, dissolved oxygen, and turbidity. Studies 

of Coal Creek found that native creek chub (Semotilus 

atromaculatusj and fathead minnow were most abundant 

(Bureau of Reclamation, 198 1). 

Several non-native species are threatening ecosystems 

in Boulder Creek, including the New Zealand mudsnail 

(Potmpyrgus antipodarum) and the Eurasian watermilfoil 

(Myrioghyllw spicatum), an aquatic plant. These species 

were accidentally introduced, have no natural predators in 

the watershed, and spread rapidly (City of Boulder, written 

cornmun., 2005). They negatively affect aquatic ecosystems 

by outcompeting native species and reducing biodiversity. A 

native species of algae, the diatom Didymosphenia geminara, 

also is affecting Boulder Creek. This diatom was once rare 

and restricted to pristine lakes and streams. In recent years, 

however, it has formed excessive growths in Boulder Creek, 

as well as many streams of Western North America (Sarah 

Spautding, USGS, oral cornmun., 2005). Loss of native species and biodiversity can lead to a decline in population and 

diversity of fish, because their fod supply has been affected. 
What is the quality of ground water in the Boulder Creek Watershed? 21 

What is the quality of ground water in the Boulder Creek Watershed? 

Surface water and ground water are closely connected; 

contamination of ground water can affect water quality of 

Boulder Creek and its tributaries. 

The mountainous part of the watershed is underlain by 

crystalline bedrmk with generally low water-storage capacity. Ground water is present in fracture zones, with depth to 

pund water ranging from tens to hundreds of feet (Bruce and 

McMahon, 1998). Most homes in the mountains are sewed by 

wells and individual sewage disposal systems (ISDSs). 

The plains part of the watershed is underlain by &entary rock, and ground-water sources are the alluvial aquifer, 

which underlies valley bottoms, and the Laramie-Fox Hills 

aquifer (Romero, 1973). The alluvial aquifer is closely connected to surface water. 

Ground-water quality in the Boulder Creek Watershed 

is not well known. Dissolvd-solids concentrations generally 

are lower in the upper watershed because crystalline bedrock 

is more resistant to dissolution by ground water (Bruce and 

McMahon, 1998). Ground-water quality can be affected by 

overlying land use, malfunctioning ISDSs, leaking underground storage tanks (LUSTS), and landfills. Application of 

pesticides and fertilizers in agricultural or urban settings can 

introduce these compounds to ground water; the pesticides 

atrazine and prometon, along with nitrate, have ken detected 

in ground water in the lower watershed (Bruce and O'Riley, 

1997). Application of chlorinated drinlung water to lawns can 

intrduix chloroform, a byproduct of drinking-water disinfection, to ground water. 

Approximately 14,400 onsite wastewater systems 

(OWSs), which include ISDSs and other systems that treat 

sewage on a property instead of discharging to a wastewater 

treatment plant, are in use in Boulder County (Boulder County 

Public Health, written commun., 2005). About one-half of 

Boulder County is in the Boulder Creek Watershed. Approximately 6,000 of these OWSs are unapproved, and 8,400 are 

more than 23 years old. Leaking OWSs have the potential 

to contribute bacteria, nutrients, and consumer products to 

ground water and surface water. 

There are dozens of underground storage tanks in the 

Boulder Creek Watershed. After many years, these steel tanks 

can corrode and leak contents to ground water. 'Ihese LUSTs 

can contain gasoline, desel, and other petroleum products. 

Methyl tertiary butyl ether (MTBE), whch has hen added 

to gasoline since the 1970s and is a potential carcinogen, has 

been found to be widespread in aIluviaI ground water of the 

Denver metropolitan area (Bruce and McMahon, 1998). 

Landfills also can be sources of ground-water contamination. The Marshall landfill, which operated from 1965 to 1992, 

was found to be leaching polychlorinated biphenyls (PCBs), 

toluene and other organics, and arsenic and other metals to 

ground and surface water (U.S. Bureau of Reclamation, 198 1). 

The site was added to the USEPA's Superfund List in 1983. A 

ground-water collection system and water-treatment facility 

were installed in 1993 and cIosed in 2004, with monitoring 

ongoing (Floyd Bebler, City of Boulder, written commun., 

2005). 

. . '. ".... -0. ; ,?d.~,: xu- ,.. 
22 State of the Watenhed: Water Quality of Boulder Creek. Colorado 

What was the quality of water in the Boulder Creek Watershed in the past? 

Prim to European-American settlement in 1 858, the 

Boulder Creek Watershed was sparsely populated by Native 

Americans, who had little effect on the landscape except 

perhaps in altering lire regimes, leading to changes in erosion 

from hihides and che1s (Wobl, 2001). Before extensive 

water management and memoir development, which began in. 

1859, streamwater discharge in much of the wahxhed wodd 

have been higher during much of the year. Dissolved solids in 

surface water would have been low in the mountains, due to 

crystalline bedrock, and higher on the plains, where bedrwk 

is sedimentary. Dissolved solids would have been lowest during snowmelt runoff. Boulder and Coal Creeks on the plains 

would have had large temperature variations, as they do today. 

Bacteria levels in the streams would have been low unless 

many people or animals were nearby. The first white settlers 

described streams in the watershed as "pure" and "fuIl of 6sh" 

(O.L. Baskin and Company, 1880). Drinking water typically 

came directly out of streams, shallow wells, or ditches and was 

not treated. 

Mlne sites and City of Boulder drlnklnpwater Imkea 

(mine data from USGS, 200Sb). 

By 1880, dozens of gold and silver mines were operating 

in the upper watershed. The first types of mines were placer 

mines, where sediment was dumped into mker hxes or 

sluices, broken apart with water, and processed with mercury. Lode mining followed., this involved crushing chunks 

of bedrock and processing it with chlorine, mercury, cyanide, 

and bromide in mills (Cobb, 1988). Lode mining, pimadly 

along Fourmile Creek, allowed much greater production; gold 

production reached its peak in 1892. Toxic chemicals used in 

processing were disposed of on the ground or in streams. Mill 

tangs caused the water in Boulder Creek downstream from 

Fourmile Creek to have a "milk-like turbidity'' (Colorado State 

Board of Health, 1878) which, when consumed, gave the "sensation of swallowing rope" (Boulder Daily Camera, 1905a). 

Mining was closely followed by timber harvesting. Boulder 

Creek was used to deliver lumber downstream, and large 

boulders and streamside vegetation were blasted to improve 

passage (Wohl, 2001). Forest fire fresuency increased, leading to erosion and release of sediment and dissolved solids to 

s&eams. 

The City of Boulder fought mines and mills to reduce 

the discharge of waste to streams (Boulder Daily Camera, 

1905b), but in 1890 avoided most contamination by moving its water intake upstream horn Fourmile Creek. In 1900, 

however, tungsten was discovered in the watershed. and many 

mines operated along Middle and North Boulder Creeks. The 

population of the upper watershed swelled. In 1807, all of 

the fish in 6everal miles of Boulder Creek were killed by mill 

waste (Ellis, 19 14). To avoid contamination by mining and 

sewage, Boulder moved its intake to North Boulder Creek in 

1906 and built Lakewood Resemoir and Pipeline. Bacterial 

cantamination continued from work camps and wttages, so in 

19 19 Boulder added additional water intakes at higher elevations, purchased much of the headwater area of North Boulder 

Creek, and eventually closed the area to the public (Phelps, 

19 16; Burns and McDonnell Engineering Co., 1921). 

Annual gold and tungsten production in Boulder County 

(data from Henderson, 1926; Lovering and Tweto, 1953; 

LUSGS, 1882-1931,1933-2000). I 
What was the quality of water in the Boulder Creek Wate~hed in the past? 23 

Placer mining on Fourmite Creek, circa 1890-1900 

(by J.B. Sturtevant: courtesy Carnegie Branch Libraw 

for Local History, Boulder Historical Society Collection) 

In the eastern part of the watershed, the towns of Erie, 

Lafayem, Louisville, Marshall, and Superior were founded 

to support underground coal mines. These communities first 

obtained drinking water hm wells. Eventually, Lafayette, 

Louisvillt, aud Erie diverted water hm South Boulder Creek. 

Early in Colorado history, inadequate disposal of human 

waste was a problem. In 1877, the newly established Colorado 

State Board of Health reported that "This beautiful land.. . blessed with good water.. . free hm all contaminations less 

than two decades since, is now, in many places, sadly changed. 

The crowded habitations which have sprung up.. . are in imminent danger of losing their healtbhhess.. . by atmospheric 

and water pollution" (Colorado State Bod of Hdth, 1877), 

Outhouses and cesspools were used throughout the Boulder 

Creek Watershed, many of these were close to drinking-water 

wells (University of colorado Extension studies, 1921). 

f 700 ,,.,.,.,,,,,.,, 

Z Ie41-MI 

PC 3 IWO 1990 1WO 1960 IWO 1870 1Q8U 

YEAR 

Annual typhoid cases (including deaths) in Boulder County, 

1902-7980 (data from Colorado State Board of Health reports, 

1902-1947 and U,S. Public Health Service, 1952-1980). 

/ 

In the Marshall Coal Mine, near tangford (now Marshall), circa 

1880-1893 (by Ira Kneeland; courtesy Carnegie Branch Library 

for Local History) 

In 1895, the City of Boulder installed its ht sewer pipes, 

which directed wage to a settling basin and then to Boulder 

Creek. However, the settling basin had little effect; for a mile 

downsham, water in the creek maembled mage, hh were 

absent, and cattle and horses re- to drink (Bishop, 1908). 

In 1905, at the same time that Boulder sought an injunction 

against mill pollution of Boulder Creek, bra downstream 

complained about Boulder emptying untreated sewage into the 

creek (Boulder Daily Camera, 1905b). South Boulder Creek 

was contaminated by bacterial pollution from resort community of Wrado Springs (University of Colorado Extension 

studies, 1921). High incidence of typhoid, wbich is carried by 

water contaminated with human waste, was recmled in 

Boulder County in the early 1900s. 

South Boulder School, Eldorado Springs, circa 1886-1890, 

with outhouse in background (by J.B. Sturtevant, courtesy 

Boulder Carnegie Branch Library, Boulder Historical Society 

Collection) 
24 Stah of the Watershed: Water Quality of Boulder Creek, Colorado 

When World War I ended, tungsten mining decreased in 

the Boulder Creek Watershed, and many mining communities 

kame ghost towns. Forest fire suppression began in about 

1920 (Wohl, 2001). These factors likely led to an improvement in water quality of the upper watershed. Sirnultmeously, 

National and State water-quality regulations, including the 

first Federal drinking-water standards, were being enacted. 

Towns and cities within the watershed began to treat drinking-water supplies with chlorination and (or) filtration (U.S. 

Public Health Service, 1950). However, poor wastewater 

disposal practices continued to result in contamination of the 

watershed. Statewide, the practice of discharging untreated 

sewage to rivers, which were then used to irrigate crops, was 

tied to typhoid fever and dysentery when people consumed the 

crops. This led several neighboring States to boycott produce 

from the South Platte Valley (Colorado State Board of Health. 

1930,1960; Chapman, 1934). Between 1934 and 1939, the 

population in Colorado served by sewagctreatment facilities increased from 6 to 84 percent (Colorado State Board of 

Health, 1939). The City of Boulder built its first WWTP in 

1934, but it did little to treat sewage effectively W.S. Public 

Health Service, 1950). Gold and tungsten wing in the upper 

watershed boomed again when the price of gold rose in 1934 

and World War II began in 1939. 

Contamination of water resources nationwide led to the 

Water Pollution Control Act of 1948, which atablished that 

States were primarily responsible for water-pollution control 

and that the Federal government would provide financial 

and technical assistance (Stoddard and others. 2002). That 

same year, a study of the South Platte River Basin found that 

Boulder Creek like most stmans in the basin, contained high 

amounts of colifonn bacteria, high biological oxygen demand 

(BOD), and low dissolved oxygen downstram from the two 

existing in the watershed IBoulder and Lafayette), 

particularly during low-flow conditions (U.S. Public Health 

Service, 1950). Erie, Louisville, Nederland, and Superior were 

still using outhouses and septic systems. 

Map rhowlng Colorado rlvers polluted with rewage and coundrr whh typhoid [ dsnhr over naclonal avmnga in IW&lOal (from Chapmnn, IWl. 
What was the quality of water in the Boulder Creek Watershed in the past? 25 

1950 to present 

The population of the City of Boulder doubled between 

1940 and 1960, inmasing wastewater ld. The City of 

Boulder built a new WWTP with secondary treatment (trickling filter and chlwination) on East Pearl Street in 1957. 

Coliform output decreased substantially, but due to continuing 

rapid population growth, the WWlT was quickly overloaded 

and released sewage with high suspended solids content and 

high biological oxygen demand (BOD) (U.S. Department of 

the Interior, 19674 b). Below the WWTP, Boulder Creek was 

murky and gray, with only a small number of tolerant organisms living in the creek. In 1968, Boulder consmcted an addi- tional WWTP on 75th Street, downstream from the Boulder 

Creek Supply Canal. Both WWTPs discharged to Boulder 

Creek until 1975, when the East Pearl WWTP began diverting 

primary effluent to the 75th Street WWTP for secondary treatment (the East Pearl WWTP closed in 1980). Water quality of 

Boulder Creek improved, but dissolvedoxygen concentrations 

were still low and the water wm murky and smelled of sewage 

(USEPA, 1972). 

By 1965, Erie and Louisville had built WWTPs, 

which along with Lafayette discharged to Coal Creek W.S. 

merit of the Interior, 1%7a). The USEPA (1972) 

found that Coal Creek was conthmbbd with coliform 

bacteria, and was chemically and bacreriologically &grading lower Boulder Creek. Contamination of gmund-water 

supplies by inadequate septic systems also was becoming 

a problem in mountainous parts of the watershed (Boulder 

Daily Camera, 1973). 

Growah of urbanized areas and westewater diaehsrge locations, 

Boulder (data from USGS, 1998). 
26 State of the Watershed: Water Quality af Boulder Creek, Colorado 

In 1972, the Federal Water Pollution Control Act Amendments (now known as the Clean Water Act) were passed, with 

the goal to "restore and maintain the chemical, physical, and 

biological integrity of the Nation's waters" and to attain "fishable and swimmable" waters throughout the Nation. The act 

required that every point-source discharger of pollutants obtain 

a permit and meet water-quality standards, and that all publicly owned WWTPs must perform a minimum of secondary 

treatment (Stddard and others, 2002). Several of the WWTPs 

in the watershed were upgraded. 

Since the Clean Water Act was passed, additional 

regulations and stricter waterquality standards have required 

WWTPs in the watershed to upgrade several times in the past 

30 years. These improvements decreased the amount of BOD, 

suspended solids, ammonia, coliform bacteria, and chlorine 

being discharged to Boulder and Coal Creeks, and increased 

dissolved oxygen concentrations below WWTPs (Arthur Dike, 

City of Boulder, written cornmun., 1985; Murphy and others, 2003, chapter 3). Industrial pretreatment programs now 

regulate the waste that industries can discharge to WWTPs. 

In 2005, the Boulder WWTP was being upgraded to improve 

ammonia removal (Floyd Bebler, City of Boulder, written 

commun., 2005). 

0 

70 60 50 40 30 20 10 0 

DISTANCE FROM SAINT VRAlN CONFLUENCE, IN KILOMETERS 

Dissolved-oxygen saturation along Middle Boulder CreeldBoulder 

Creek in 1950,1978, and 2000-2004, and locations of wastewater 

discharge (from 1966 to 1975,there were two WPs discharging 

to the creek; data from U.S. Public Health Service, 1950; 

Kodadek, 1978; City of Boulder). '. a' 

Population growth in the watershed continued to 

increase rapidly. The combined populations of the four communitiw discharging to Coal Cmk, historically a very low 

flow stream. increasd from 7,168 in 1970 to 57,436 in 2000 

(U.S. Census Bureau, 2001). All of these communities (Erie, 

Lafayette, Louisville, and Superior) upgraded or built new 

WWTPs in the past 20 years to accommodate this growth. 

l'l',' 

L Longmont 

Superlor 

Erie 

Bmfleld' 

I Boulder 

I YEAR I 

Population of Boulder County, 18&2000 (data from U.S. 

Census Bureau, 2001;"Erie and Broomfield populations 

include only portions within Boulder County; Broomfield 

became a separate county in 2001 1. 

28 State of the Watershed: Water hali of Boulder Creek, Colorado 

How does water quality in the Boulder Creek Watershed compare to other Front 

Range watersheds and to watersheds nationwide? 

The National Water-Quality Aswssment (NAWQA) Program of the USGS assesses water quality of watersheds across the 

United States. NAWQA stu&es indicate that contaminants are widespread, albeit commonly at low concentrations, across a wide 

range of landscapes and land uses (Hamilton and others, 2004). The highest nutrient and pesticide concentrations were detected 

in agricultural and urban sb-eams. These streams usually contain complex mixtures of nutrients and pesticides. Nationally, at 

least one pesticide was found in 94 percent of all surface-water samples. Contaminant concentrations varied with seasons, typically with long periods of low or nondetectable concentrations and brief periods of much higher concentrations. 

The South Platte River Watershed, which includes the 

Boulder Creek Watershed, has been studied as part of the 

NAWQA Program. The NAWQA study evaluated data based 

on five land-use categories: forest, agricultural, urban, mixed 

urbdagricultural, and rangeland. The study found that water 

quality in the forested mountain region of the South Platte 

River Watershed was generally good, while water quality 

in urban and agricultural areas was degraded (Dennehy and 

others, 1998). Most surface-water qpling sites located in 

urban, agricultural, and mixed wbadagricultural land-use 

areas had nutrient concentrations that were among the . highest 25 percent of all 20 NAWQA study units sampled 

during 1992-95 (that is, 75 percent or more of samples from 

each site had total nitrogen concentrations greater than 

7.3 mg/L as N and total phosphorus concenkations greater 

than 0.87 mg/L as P). Total nitrogen concentrations in 

strearns along the Colorado Front Range were substantially 

greater downstream from WWTPs. Nutrient levels in mountain and rangeland sampling sites in the South Platte River 

Watershed, however, were among the lowest nationally. 

Water-quality data for Boulder Creek are sirmlar to data 

hm the South matte River Watershed NAWQA study in the 

same land-use categories. Nutrient concentrations in forested 

headwater Ad mountain regions are low or undetectable; 

downsm from urban areas, nutrient concentrations are 

within the range of the highest 25 percent of the NAWQA 

study units (Murphy and Waterman, 2005). 

Ranking of nutrient concentrations in the South Platte River 

Watershed relative to all NAWQA stream sites (bold outline of 

circle indicates one or more aquatic-life criteria were exceeded; 

, from Dennehy and others, 19%). 

EXPLANATION 

DOMINANT LAND USE 

Stwins and rivers 

S,Il, gm., ,r 

Majoraquifm 

Total nitrogen in streams and nitrate in ground water for all 

( USGS NAWaA study units (from USGS, 1999). 

. ( laf-on about !he USGS NAWQA pmgram is 
What will be the water-quality issues in the Boulder Creek Watershed in the future? 29 

What will be the water-quality issues in the Boulder Creek Watershed in the 

future? 

As population has grown in the Boulder Creek Watershed, potential water-quality effects from urbanization have inmad. 

Cwversion of forest and agricultural land to urban land use has resulted in increased impavious surface area, which cause3 

rain and melted snow to travel quickly to streams as surfamwater MOB, carrying sediment and accumdatd cwtamhmts. 

Construction also contributes sediment to smam if runoff is not controlled. In 2001, CDPHE enacted regulations that require 

urban areas with populations over 10,000 to manage stormwater to reduce pollutant loading (CDPHE, 2005f). These regulations 

require public education, illicit discharge detection and elimination, construction site stormwater moff control, and pollution 

prevention for municipal operations. In the Boulder Cmk Watershed, these regulations affect Boulder County and the citk 

of Boulder, Erie, Lafayette, Louisville, and Superior. Thc listing of Bouldcr Creek through the city of BOW as an impaired 

stream because of high levels of E. coli has also focused attention on urban rund. Identifying sources of bacteria is diflicult, 

and research is ongoing (Stoeckel and othem, 2004). 

4 

Momdon about stormwater programs in the 

watershed is available from the Watershed 

Increased population means more wastewater, which 

contributes nutrients and organic wastewater contaminants 

to streams. However, WWTP expansions to accomm&te 

growth usually improve nutrient removal. The Boulder 

WWTP, the largest contributor of ammonia to the watershed, 

is being upgraded to improve ammonia removal. Organic 

wastewater contaminants, such as pharmaceutical drugs, hormones, and cleaning products, which are generally not repIated, have been found in effluent from the BouIder WWTP 

and WWTPs and rivers throughout the Nation (Kolpin and 

others, 2002; Murphy and others, 2003, chapter 5). The effects 

of many of these compounds are unknown, and there are no 

Cleaning products 

waterquality standards for most of them. Potential cuncerns 

include abnormal physioIogical pmesses and repductive 

impairment (Daughton and Ternes, 1999). Studies of fish in 

Boulder Cmk and the South Platte River downstream from 

WWTPs detected a high female to male ratio and reproductive abnormalities (Vajda and others, 2004). New analytical 

research into the ecological effects of these emerging contaminants is needed to fully understand human health and ecosystem implications. 

While population growth and urbanization in the Boulder Creek Watershed has been rapid in recent years, the rate 

of growth wilI Iikely be lower in the future. BouIder County 

and communities within the county have preserved about 

445 square kilometers (1 10,000 acres) of land as open space 

or conservation easements (Boulder County Parks and Open 

Space, written commun., 2005). There is also open space in 

Broomfield, Jefferson, and Weld Counties within the water- Land ownership in the Boulder Creek Watershed in M05 (data 

shed. Much of is national forest or city- provided by U.S. Foresl Sewice, Boulder County, and Jefferson 

owned protected watershed property. County). 
30 State of the Watershed: Water Quality of Boulder Creek, Colorado 

Summary 

Boulder Creek and its tributaries are vital for providing drinking water, agricultural irrigation, aquatic habitat. recreation, 

and power generation. The suitability of water for these uses is commonly determind by water quality. Water quality in the 

Boulder Creek Watershed is affezted by natural factors such as geology, climate, and physiography, and human-caused factors, 

such as wastewater effluent, runoff from roads and urbanized mas, agricultural practices, atmospheric contaminants, and other 

sources. Waterquality effects are compounded by the many water diversions in the watershed, which often leave little water in 

streams to provide dilution. The relative effect of these factors on water quality has changed over time and will continue to shift 

with changes in land and water use. Knowledge of water quality is important for effective water-resource and land-use planning. 

This report provides an assessment of water quality in the Boulder Creek Watershed at the beginning of the 21st century and 

how it has changed over the past 160 years. The information can be used as a baseline for evaluating waterquality changes in 

the future. 

m 

Middle Boulder Creek 
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34 State of th~ Watershed: Water Quality of Boulder Creek, Colorado 

1 Acknowledgments 

! Many people assisted in the preparation of this report by providing data, information, or review. I thank F'loyd Bebler, 

Jennelle Freeston, Ed Mead, Curry Rosato, Chris Rudkin, Donna Scott, Brad Segal, Jim Shelley, Betty Solek, and Jim Stout 

of the City of Boulder; Larry Barber, Bret Bruce, Steffanie Keefe, Joseph Kerski, Mary Kidd, Deborah Martin, David Mixon, 

Carol Mladinich, Lori Spmgue, Robert Stallard, Steve Vandas, and Philip Verplanck of the USGS; Douglas Short of the City 

I of Lafayette; Lane Drager and Heath Hannon of Boulder County Public Health; Bill McKee of the Colorado Department of 

I Public Health and Environment; Enc Schroder of the U.S. Forest Service; the Camegie Branch Library for Local History; 

Katherine Aermann; Lee Rozaklis; Ed Raines; and Jim Waterman. Ground-water diagram prepared by John Evans. Timeline 

design provided by Jim Robb. All other photographs and figures prepared by the author unless noted. 

For more information 

About the Boulder Creek Watershed: 

Boulder Area Sustainability Information Network: 

www.BASIN.org 

USGS studies on the Boulder Creek Watershed: 

http://wwwbrr.cr.usgs.govlprojectslS WC-Boulder-Watershedl 

About communities within the watershed: 

Boulder County 

Post Office Box 47 1 

Boulder, CO 80306 

(303) 441-3131 

http:l/www,co.boulder.co.us 

I 

City of Boulder 

1739 Broadway 

Boulder, CO 80302 

(303) 441-3266 

http:llwww.ci.boulder.co.us 

City and County of Broomfield 

One DesCombes Drive 

I Broomfield, CO 80020 

(303) 438-6390 

http:llwww.ci.broomfield.co.us/ 

City of Lafayette 

1290 South Public Road 

Lafayette, CO 80026 

(303) 665-5588 

http:llwww.cityoflafayette.com 

City of Louisville 

749 Main Street 

Louisville, CO 80027 

(303) 666-6565 

http:llwww.ci.louisville.co.us/ 

Gilpin County 

203 Eureka Street 

Central City, CO 80427 

(303) 582-52 14 

http:llco.gilpin.co.usl 

Jefferson County 

100 Jefferson County Pkwy 

Golden, CO 80419 

(303) 279-65 i 1 

http:llco.jefferson.co.usl 

Town of Erie 

645 Holbrook, PO Box 750 

Erie, CO 805 16 

(303) 926-2700 

http:llwww.ci.erie.co.us/ 

Town of Nederland 

P.O. Box 396 

Nederland, CO 80466 

(303) 258-3266 

http://town.nederland.co.us/ 

Town of Superior 

124 E. Coal Creek Drive 

Superior, CO 80027 

(303) 499-3675 

http://www.townofsuperior,corn/ 

Weld County 

1555 N. 17th Ave. 

Greeley, CO 8063 1 

(970) 356-4000 

http:llwww.co.weld.co.us/