State of the Watershed: Water Quality of Boulder Creek, ColoradoBy Sheila F. MurphyPrepared in cooperation with the City of Boulder, ColoradoU.S. Geological Survey Circular 1284U.S. Department of the InteriorU.S. Geological SurveyU.S. Department of the InteriorGale A. Norton, SecretaryU.S. Geological SurveyP. Patrick Leahy, Acting DirectorU.S. Geological Survey, Reston, Virginia: 2006For sale by U.S. Geological Survey, Information Services Box 25286, Denver Federal Center Denver, CO 80225For more information about the USGS and its products: Telephone: 1-888-ASK-USGS World Wide Web: http://www.usgs.gov/Any use of trade, product, or firm names in this publication 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 are noted in the text. Permission to reproduce those items must be secured from the individual copyright owners.Library of Congress Cataloging-in-Publication DataMurphy, Sheila F. State of the watershed : water quality 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—dc222005035604ISBN 1-411-30954-5ContentsWelcome to the Boulder Creek Watershed ..............................................................................................1Environmental Setting ...................................................................................................................................2Hydrology ........................................................................................................................................................6How does water management affect the flow of Boulder Creek? ........................................................8How clean is the water in Boulder Creek? ................................................................................................9Water Quality of Boulder Creek from Top to Bottom..............................................................................12What fish species live in Boulder Creek? ................................................................................................20What is the quality of ground water in the Boulder Creek Watershed? .............................................21What was the quality of water in the Boulder Creek Watershed in the past? ..................................22Timeline for the Boulder Creek Watershed .............................................................................................27How does water quality in the Boulder Creek Watershed compare to other Front Range watersheds and to watersheds nationwide? .....................................................28What will be the water-quality issues in the Boulder Creek Watershed in the future? ..................29Summary........................................................................................................................................................30References ....................................................................................................................................................31Acknowledgments .......................................................................................................................................34For more information ...................................................................................................................................34iiiWelcome to the Boulder Creek WatershedThe 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, Lafayette, Erie, Superior, and Nederland are 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 agriculture. In the semiarid environment of the Colorado Front Range, water resources are limited, 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. This report, prepared by the U.S. Geological Survey in cooperation 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.ClearCrPoudreThompsonBijouCrKiowaCreekCrowLoneLodgepoleSouthWYOMINGNEBRASKACOLORADOBoulderCrCherryCrBearNorthCachePlatteRiverCreekCreekCreekCreekLaRRStVrainCrPlumSouthPlatteRCrCrTreeBeaverForkBigBoulder CreekWatershed0 40 KILOMETERSBoulder Creek Watershed (from Murphy and others, 2003)Mississippi River WatershedSouth Platte River WatershedComo CrMiddleBoulderBoulderCrRock CrSouthBoulderMarshall LakeBaseline ResValmontResBoulder Cr.Coal CrFourmile CrDivideNiwot RidgePanamaRes # 1BOULDER COGILPIN COBOULDER COJEFFERSON COSuperiorBroomfieldLouisvilleLafayetteBoulderErieNederlandFrederickArvadaIndian PeaksWildernessAreaCity of Boulderprotectedwatershedproperty£¤287527937236WELD COBOULDER COBROOM-FIELDCOMOUNTAINS PLAINS119Cr.119"EldoradoSprings"MarshallNorthCrBoulderCrLakewoodResSouthBoulderCrCoalContinentalCrGross ResBarkerRes10 KILOMETERS0NEnvironmental SettingThe Boulder Creek Watershed lies within two physiographic provinces. The mountainous upper watershed is part of the Southern Rocky Mountains Province and is characterized by deep,