Ecological effects of the Lawn Lake Flood of 1982, Rocky Mountain National Park PDF
Preview Ecological effects of the Lawn Lake Flood of 1982, Rocky Mountain National Park
room wi2-o issc^rce 1 ^omo Please do not remove r^e^. ^teiMes> this item from Room Resource Ecological Effects of the Lawn Lake Flood of 1982, Rocky Mountain National Park Scientific Monograph NPS/NRROMO/NRSM-93/2 United States Department ofthe Interior National Park Service TheNationalParkServicepublishesscientificstudiesofsignificantnaturalresources inunitsoftheNationalParkSystem. Thisresearchisofscholarlyqualityandmayinclude anydisciplineofthebiological, physical,orsocial sciences. Editorial Staff FishandWildlifeService PaulA. Opler ManagingEditor PaulA. Vohs SubjectEditor NationalParkService DonnaL. O'Leary PublicationsCoordinator JerryD. Cox TechnicalEditor SuzanneD. Hardy EditorialAssistant MarthaW. Nichols EditorialAssistant CoverPhoto:AbackdropofmountainsinRockyMountainNational Park,Colorado,highlightsthealluvialfancreatedby theLawnLakeflood. CopiesofthisreportareavailablefromthePublicationsCoordinator,NationalPark Service, Natural Resources Publication Office, P.O. Box 25287, Denver, CO 80225- 0287. ISSN 0363-0722 fig* NATIONAL PARK SERVICE WATER RESOURCES DIVISION ;^*3 FORTCOLLINS, COLORADO RESOURCE ROOM PROPERTY Ecological Effects of the Lawn Lake Flood of 1982, Rocky Mountain National Park Editors Henry E. McCutchen NorthernArizona University CooperativeParkStudies Unit Flagstaff,Arizona 86011 Raymond Herrmann NationalParkService Colorado State University WaterResources CooperativeParkStudies Unit ' FortCollins, Colorado 80523 David R. Stevens1 ^ RockyMountainNationalPark EstesPark, Colorado 80517 Scientific Monograph NPS/NRROMO/NRSM-93/21 United States Department ofthe Interior National Park Service •1993- 'Presentaddress: NationalParkServiceAlaskaRegionalOffice, Anchorage,Alaska99503. Contents Page Foreword iv Hydrology andGeomorphology ofthe 1982 Lawn Lake Dam Failure, Colorado. RobertD.JarrettandJohnE. Costa 1 Geomorphic Response ofthe Fall River, Rocky Mountain National Park, Colorado.JohnPitlick 18 Alpine Sediment Movementand Erosion in theRoaring River Watershed, Rocky Mountain National Park. RebeccaM. Summer 33 Geochemistry ofIron Oxides in the Roaring RiverAlluvial Fan, Rocky Mountain National Park, Colorado.M. IggyLitaorand RichardB. Keigley 55 Micronutrient Status ofTree Species Affectedby the Lawn Lake Flood in Rocky Mountain National Park, Colorado. KennethA. Barrickand MarkG. Noble 70 Vegetation Developmenton the Exposed Shores ofLawn Lake. Donald H. Mansfield 86 Macroinvertebrate Community Recovery Following Episodic Flooding From an Earthen Dam Failure. DavidR. Beeson andTerenceP Boyle..112 Terrestrial Arthropod Faunaofthe Alluvial FanResulting From the Lawn Lake Flood. HowardE. Evans 138 Colonization ofthe Lawn Lake Alluvial Fan by Amphibians: Potential Effects ofBiotic and Abiotic Factors. Linda C. Zimmerman and C. RichardTracy 148 Changes in Avian Breeding Populations Resulting From the Lawn Lake Floodof 1982.RonaldA. RyderandDeborah WestBangs 163 Effects ofthe Lawn Lake Flood on Local Distribution and Abundance ofMammals. DavidM.Armstrong 170 Observations ofPlantEcology on the Lawn Lake Flood Alluvial Fan. RichardB. Keigley 192 in Foreword Lawn Lake is located at treeline, 3,350 m (10,987 feet) above sea level. It is inoneofthemostscenic areasofRocky Mountain National Park, Colorado. In 1903, aprivatelyconstructeddamenlargedthelaketo store waterforirriga- tion. These activities preceded the designation of Rocky Mountain National Park in 1915; because ofthe established waterrights, the dam continued to be privately managed, maintaining an easement within national park property. On 15 July 1982, the dam at Lawn Lake failed, probably due to a piping m failure. The subsequentflood—sentapproximately 831,000 3 ofwaterca—scad- ing down the Roaring River causing the Cascade Lake Dam to fail and then continuing through the townofEstes Park. Three people were killed, and nearly$30millionofdamageoccurred. ThepresidentdeclaredLarimerCounty adisasterareaon 22July 1982. Failure of the dam released a torrent that scoured the drainage of the Roaring River, inundated adjacent ecosystems, and deposited a large debris fan at the confluence ofthe Roaring and Fall rivers in the park. The physical andbiologicaleffects ofthe flood were profound, particularly within thepark. As perturbations ofthis type in high-elevation ecosystems are rare, the flood captured the interest of local, national, and international scientists and scholars. The period following the Lawn Lake Flood was recognized by the Na- tional Park Service (NPS) as arare opportunity to study andbetterunderstand ecosystems affectedbycatastrophicflooding. Thepresentstudyrepresents the resultsofthelast8yearsofmultidisciplinaryresearch.In 1983,GustavSwanson, professoremeritus ofColorado State University, focusedthe NPS effortwhen he proposed the concept ofdeveloping aresearch consortium forthe flood. In May 1983, these thoughts became reality when the park hosted a meeting and field trip for interested investigators. From that first meeting, plans rapidly developed and were put in motion for the organization and funding of a multidisciplinary research effort to investigate the physical and biological ef- fects ofthe flood as well as the area's subsequentrecovery. The NPS Rocky Mountain Region and the NPS Water Resources Field SupportLaboratory initiated the program. Later, additional help was obtained from the National Park Service's Natural Resources Preservation Program. Contributions of additional value were made by other government and private sources. In addition, many ofthe contributors to this volume donated theirprofessional skills andtalents totheseefforts. The result has been a multidisciplinary scientific study of an unusual — event a study that details many research efforts focused toward understand- ing the effects ofand the response to the catastrophic flood on 15 July 1982. As theirtitles reflect, the 12 studies presented here have covered many physi- cal and biological science disciplines, including geology, hydrology, chemis- try, botany, and zoology. The studies tell the story of the ecological changes that followed the failure of Lawn Lake Dam and the subsequent flood that produced rapid hydrologic changes, including inundation, scouring and depo- sition (burial), nutrient and mineralogic changes, sediment accommodations, and direct biological effects. Finally, these studies detail the recovery pro- cesses that occurred inboth aquatic and terrestrial biological communities. Many important publications on the effects of and the response to the flood were presented before those in this symposium. One ofthe major ones, published in 1986, is the 78-page U.S. Geological Survey Professional Paper by R. D. Jarrett and J. E. Costa titled Hydrology, Geomorphology andDam- breakModeling oftheJuly15, 1982,LawnLakeDamandCascadeLakeDam Failures, Larimer County, Colorado. Jarrett and Costa have provided a con- densed version of that monograph for this volume. A number ofreports and publications have stemmed from the research of Dr. Colin Thorne (Queen Mary College, London, England) and his associates. This series of five re- ports, printed as technical reports ofthe NPS Water Resources Field Support Laboratory,arenotreprintedinthisvolumebecauseofspaceconstraints.These reports includeBedloadTransportandHydraulicGeometryRelationsforFall River,RockyMountainNationalPark, Colorado(1984),byJohnP. Hick;Bed Material Analysis on the Fall River (1983), by David S. Biedenb—ain; two reports, Measurements ofBend Flow Hydraulics on the Fall River at Low Stage (1983), and—atBankFullStage (1985), by Colin R. Thorne et aL; and StreamDischargeRating CurvesfortheFallRiver,RockyMountainNational Park (1983), by Mark Segenthaler. Copies of these reports may be obtained from the U.S. Department of the Interior, National Park Service, Water Re- sources Division, Fort Collins, Colorado. Another article of interest can be found in theJournalofSedimentaryPetrology 57(1):1-18, titledSedimentary Processes, VerticalStratificationSequences,andGeomorphologyoftheRoar- ingRiverAlluvialFan,RockyMountainNationalPark, Colorado,by Terence C. Blair. — We again thank the authors and investigators who persisted with mini- — mal NPS help to complete their studies. These studies represented a rare opportunity to learn more about a phenomenon of great importance to re- sources managers within the National Park Service and to land managers ev- erywhere. Theresultsoftheirworkhavehelpedtobetterunderstandthenature of riparian changes that occur owning to catastrophic flood events and the recovery process thatfollows. James B. Thompson Superintendent, Rocky Mountain National Park The Editors OoJ c a i- 7u3 d< a. Cd sa) a> "eo E Cd T3 MU Jcd c £ Cd -J u coj J= *-* <^ '-c!- W)4-Oi _2c lC_D, i cd E E 3 -o C/D £<u -cCu S- ^c <<Gu c cd u o i c IS cd >, £ <d o c>d -oC _*C"cJ' a<D. c sHCh o T3 § S .J2 J -a £ Is > 3 cd cud Tu3 XH! cd a; o aaeu>J "CcTd3 «3 & ao cUd t- u. VI Hydrology and Geomorphology of the 1982 Lawn Lake Dam Failure, Colorado Robert D. Jarrett U.S. GeologicalSurvey P.O. Box25046,MS418 Denver, Colorado80225 John E. Costa U.S. GeologicalSurvey 5400MacArthurBoulevard Vancouver, Washington 98661 Abstract. Failure ofthe Lawn Lake Dam released 831,000 m3 ofwater with an estimatedpeakdischargeof510m3/sdowntheRoaringRivervalley.Floodwatersfrom LawnLakeDamovertoppedaseconddam withapeakdischargeof204m3/s. Cascade Lake Dam, 10.8kmdownstream,alsofailedandincreasedpeakdischargeto453 m3/s. Cascade Lake Dam, a 5.2-m-high concrete gravity dam with acapacity of 14,900 m3 , failedas 1.28mofwaterflowedoveritscrest.ThefloodcontinueddowntheFallRiver into the town ofEstes Park, where it caused extensive damage. Peak discharge in the Big Thompson River at Estes Park was 156 m3/s. We present a summary ofthe dam failures, hydrologic anddam-breakmodelinganalyses, adiscussionofthegeomorphic effects of the flood, and an overview of the effects of the flood on the public. The documented 1982 flood indicates the need to improve the understanding offloodpro- cesses so that modeling dam-break floods in high-gradient rivers can be improved. Thesestudyresultsprovidehydrologic,geomorphic,andflooddamageinformationfor the assessment of floods from dam failures and baseline information for scientists conductingrelatedresearch. Introduction /startedto heara soundlikean airplane. Also, therewere loudbooms. It got louderandlouder. Ithought itwas breaking the soundbarrier. Ikept looking for a plane but couldn't see one. I got suspicious and started looking upstream. I saw trees crashing over anda wall ofwater coming down. I started to run asfast as I couldfor high ground. There was a deafening roar. Ifellandgotupandkeptrunning. Istoodon high ground and watched it wipe out our campsite. It knocked everything in its path over;Steve [his camping companion] didn'tstanda chance. 1 R. D.JarrettandJ. E. Costa With these words, Steven Cashman described his harrowing experience with the flood that swept his camping companion to his death in the Roaring River. Other campers along the Roaring River estimated the wall of water to be 8-10 m high, carrying with it large trees and boulders, so that the water looked like a wet, brown cloud that sounded like extremely loud continuous thunder, orafreight train, oran airplane breaking the soundbarrier. After Cascade Lake Dam failed, two other campers were swept to their deaths a shortdistance downstream from the dam. The floodcausedextensive damage to homes, businesses, and bridges, particularly in the town of Estes Park. Dave Thomas, observing the flood from a point 1.9 km—upstream from Estes Park, indicated the floodwave "gradually began to swell there was no wall ofwater." In Estes Park, the flood entered the Big Thompson Riverfora shortdistancebeforebeingcontained within Lake Estes by the U.S. Bureauof Reclamation's Olympus Dam, which—is about 20—km downstream from Lawn Lake. Peak discharge into Lake Estes 156 m3/s occurred about 3 h40 min afterthefailureofLawnLakeDam. Inthatbrieftime,threepeople werekilled andapproximately$31 millionoftotalflooddamagewasincurred. Flooddam- ages included private and public property losses, debris cleanup, and eco- nomic losses to businesses in the Estes Park area. As a result ofthe flood, the presidentdeclared LarimerCounty adisasterareaon 22July 1982. The Lawn Lake Dam failure provided an opportunity to improve the un- derstanding ofhydraulic and geomorphic processes of large floods and their effect on stream channel morphology in mountainous areas. This paper pre- sents the setting, a summary ofcauses, effects on hydrology andgeomorphol- ogy, and effects on the public of the dam failures and flood. Dam-break computermodeling was used to provide supplemental hydrologic information and to evaluate various hypothetical scenarios of dam-breach development and probable effects ofthe failure ofCascade Lake Dam. Documentation and analysis of the flood provide valuable information on the effects of floods from failure ofsmall dams on high-gradient streams. This information can be used for future hazard mitigation related to dam failures and for studying the effects of floods from dam failures. Because the dam-failure flood occurred within National Park System lands, study ofthis flood enhanced the National Park Service (NPS) dam safety program and its relation to park resources. Setting LawnLake was an artificially enlargednatural lake occupying amoraine- dammed depression on the southeast side of the Mummy Range in Rocky Mountain National Park, Colorado (Fig. 1). The elevation ofthe lake is about 3,350 m. Local bedrock consists ofPrecambrian gneisses and schists that are morethan 1.7billion yearsold(Petermanet al. 1967). LawnLake isfedbythe Roaring River, which originates at Crystal Lake, a tarn located about 1.6 km upstream at an elevation of about 3,500 m. Upstream from Lawn Lake, the
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