DOCSLIB.ORG

Geology of Unaweep Canyon and Its Role in the Drainage Evolution of the Northern Colorado Plateau

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Geology of Unaweep Canyon and Its Role in the Drainage Evolution of the Northern Colorado Plateau CRevolution 2: Origin and Evolution of the Colorado River System II themed issue Soreghan et al. Geology of Unaweep Canyon and its role in the drainage evolution of the northern Colorado Plateau Gerilyn S. Soreghan1, Dustin E. Sweet2, Stuart N. Thomson3, Sara A. Kaplan1, Kristen R. Marra1, Greg Balco4, and Thaddeus M. Eccles1 1School of Geology and Geophysics, University of Oklahoma, 100 East Boyd Street, Norman, Oklahoma 73019, USA 2Department of Geosciences, Texas Tech University, 125 Science Building, Box 41053, Lubbock, Texas 79409, USA 3Department of Geosciences, University of Arizona, 1040 E. 4th Street, Tucson, Arizona 85721, USA 4Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, USA ABSTRACT Thermochronological data from Precam- teau and is the only major canyon in the Colo- brian basement within Unaweep Canyon rado River drainage not occupied by a river. It Unaweep Canyon (Colorado, USA) is a and Permian strata at the western mouth penetrates Mesozoic strata deep into Precam- large, Precambrian-cored gorge that bisects of the canyon indicate onset of incision in brian crystalline basement, but paradoxically the Uncompahgre Plateau of the northeastern latest Miocene time (ca. 6–5 Ma), at a time- hosts two underfi t drainages, East Creek and Colorado Plateau, but has no through-fl ow- averaged rate of ~210–275 m/m.y. Onset of West Creek, which fl ow in opposite directions ing axial stream; it is drained by two underfi t canyon occupation and rapid incision by the from a gentle divide within the canyon (Figs. creeks (East and West Creek) that head at a ancestral Gunnison River coincided with the 1 and 2). For this reason, Unaweep Canyon is divide within the canyon. The history of the timing of integration of the lower Colorado said to be the only canyon in the world with canyon and its role in drainage evolution of River system to the Gulf of California. The two mouths. the Colorado River system remain contro- synchroneity of this incision across the Colo- Originally described by the Hayden Sur- versial. New mapping of both bedrock and rado Plateau supports the inference of an vey of the late 1800s (Peale, 1877; Gannett, Quaternary units as well as analyses of Qua- ultimate tectonic or epeirorogenic driver for 1882), the origin of Unaweep Canyon remains ternary deposits in and near the canyon shed this widespread incision and ultimate drain- debated. All agree that the creeks currently light on its late Cenozoic history, and call into age integration. occupying the canyon are markedly underfi t. question whether the canyon was incised by Several aspects of this data set support Most have hypothesized that the canyon origi- a Cenozoic river, or merely exhumed by one. the previously published hypothesis that the nated from fl uvial erosion related to an ances- Gravels near the western mouth of Unaweep ancestral Gunnison River exhumed a paleo- tral Gunnison and/or Colorado River, which Canyon (Gateway, Colorado) exhibit a dis- valley. New mapping at the western mouth subsequently abandoned the canyon; but its tinctive intermediate volcanic provenance of the canyon documents a paleovalley fi lled odd geomorphology has aroused speculations recording the presence of an ancestral Gun- with Permian strata that leads into the mod- of a possible glacial infl uence. Soreghan et al. nison River; the youngest gravels are dated to ern Precambrian-hosted gorge of Unaweep (2007) proposed a late Paleozoic age for the 1.46 ± 0.33 Ma. Previously documented cor- Canyon. In addition, the ancestral Gun- Precambrian-hosted inner gorge of Unaweep ing within the canyon reveals a thick (locally nison River paralleled the Uncompahgre Canyon; Soreghan et al. (2008, 2014) fur- >330 m) fi ll that includes a lacustrine succes- Plateau before making a 90° turn to bisect ther suggested an initial (Paleozoic) glacial sion (~140 m thick), dated to 1.4–1.3 Ma, over- the structural axis in a manner that opposes origin followed by Cenozoic fl uvial exhuma- lain by stacked paleosols and a thick (~160 m) both the northwestward plunge of the uplift tion of the ancient valley. Both the Paleozoic conglomeratic unit emplaced between 1.3 Ma and the northeastward dip of its northern age and glacial origin remain controversial and the present, in addition to a basal unit of fl ank. The rate of incision of Unaweep Can- (Aslan et al., 2008, 2014; Hood, 2009; Hood possible late Paleozoic age. Lake formation yon exceeds regional time-averaged incision et al., 2009). refl ects catastrophic mass wasting in western rates, consistent with removal of sedimen- Unaweep Canyon would remain a geomor- Unaweep Canyon that blocked the ancestral tary fi ll rather than incision of crystalline phic oddity of primarily local curiosity were it Gunnison River, causing partial backfi lling basement. This hypothesis implies that very not positioned atop the Colorado Plateau and of the canyon, and forcing the river to seek ancient landforms can infl uence drainage connected to the history of the greater Colo- a lower elevation exit eastward by breach- evolution in even tectonically active land- rado River system, and possibly a deeper time ing the Mesozoic rim at the northeast end of scapes. history of the region. Resolving the geologic Cactus Park (Mesa County, Colorado). Ulti- history of Unaweep Canyon, including the tim- mately, the ancestral Gunnison River joined INTRODUCTION ing and processes of incision and abandonment the lower elevation Colorado River near of the canyon, contributes to our understand- Grand Junction by 1.3 Ma, incising the East Unaweep Canyon (western Colorado, USA) ing of the tectonic, geodynamic, and geomor- Creek of Unaweep Canyon during the over- bisects the northwestward-trending Uncom- phic forces driving Cenozoic integration of the spilling event. pahgre Plateau on the northern Colorado Pla- Colorado River system across the Colorado Geosphere; April 2015; v. 11; no. 2; p. 320–341; doi:10.1130/GES01112.1; 15 fi gures; 1 table; 1 plate; 2 supplemental tables. Received 2 August 2014 ♦ Revision received 26 November 2014 ♦ Accepted 3 February 2015 ♦ Published online 11 March 2015 320 For permissionGeosphere, to copy, contact April [email protected] 2015 © 2015 Geological Society of America Downloaded from http://pubs.geoscienceworld.org/gsa/geosphere/article-pdf/11/2/320/3334569/320.pdf by guest on 30 September 2021 Geologic history of Unaweep Canyon 109° 108° Colorado Uncompahgre Plateau UT Plateau CO FFS CLI • OOK B er iv ND VAL R RA LE G Y o d AZ a NM r er Grand Junction lo iv o R C o d ra lo GRAND 39° o C k Whitewater MESA e Unaweep e G r u Pure Oil #1 C n Divide st n Ea iso N n Creek R t YO iver s N Cactus e UNAWEEP CA WEST ELK Do W Park B lo l MOUNTAINS r Gateway a e U U c s N n k R COM c C i a v o nyo e m n LA SAL r PAH o p f GRE P ah th MOUNTAINS g e re Gunnison River L R A iv TE e AU r San Mig ue l R iv er D o l o r e s 38° R SAN JUAN iv e r MOUNTAINS Figure 1. Digital elevation model of the Uncompahgre Plateau and greater study region with key features labeled. Boxed region shows the approximate area of the geologic map in Plate 1. White stars (left—ca. 0.96 Ma gravels, right—ca. 1.2 Ma gravels; Carrara, 2001) indi- cate locations of ancient Colorado River gravels sampled in this study (see text and Supplemental Table 2 [see footnote 2]). The white line through the canyon from Gateway (west) to Whitewater (east) is the line of section shown in Figure 12. Plateau, a primary theme of this special issue. chrono logical data from units within and near GEOLOGIC SETTING Moreover, if the Cenozoic history of Unaweep western Unaweep Canyon to (1) document the Canyon proves to be one of exhumation, late Cenozoic occupation and abandonment of Colorado and Uncompahgre Plateaus rather than incision, it implies preservation Unaweep Canyon by a large tributary of the (through burial) of a paleolandform of exces- upper Colorado River system and identify that The Colorado and Uncompahgre Plateaus sive antiquity . Note that here we use the geo- tributary, and (2) assess the hypothesis that this form part of the greater Rocky Mountain oro- morphic defi nition of exhumation as referring late Cenozoic fl uvial history was one of rapid genic plateau, a large region of high elevation in to the exposure through erosion of a formerly exhumation of a pre-Cenozoic landform, rather the United States (McMillan et al., 2006). The buried landscape. Preservation of landscapes than primary incision. If valid, this scenario area has undergone multiple episodes of uplift, of great antiquity (e.g., Mesozoic, Paleozoic) implies a strong role for a form of historical including the Pennsylvanian to early Permian is well known from, e.g., cratonal regions of contingency in landscape evolution. These data rise of the Ancestral Rocky Mountains, which the Gondwanan continents (e.g., Twidale, bear on long-debated issues regarding the iden- included the Uncompahgre uplift, a precursor 1998, 2003), but less appreciated for tectoni- tity of the river or rivers that occupied Unaweep to the modern Uncompahgre Plateau (Kluth cally active regions, although debate continues Canyon, the cause and timing of river abandon- and Coney, 1981). The southwestern edge on the possible role of paleocanyons in shap- ment, the postabandonment history, the odd of the Uncompahgre Plateau coincides with ing the lower Colorado River system (Flowers orientation that crosscuts regional drainage pat- the southwestern margin of the late Paleozoic et al., 2008; Wernicke, 2011; Flowers and terns, and broader implications for identifying Uncompahgre uplift, defi ned by the Uncom- Farley , 2012, 2013).
Load more

Recommended publications
  • Dolores River Restoration Partnership: a Private/Public Collaboration Dolores River Restoration Partnership
    DOLORES RIVER RESTORATION PARTNERSHIP: A PRIVATE/PUBLIC COLLABORATION DOLORES RIVER RESTORATION PARTNERSHIP • TIMELINE OF PARTNERSHIP • VISION AND GOALS OF PARTNERSHIP • WHY HAS THE DRRP BEEN SUCH A SUCCESSFUL PARTNERSHIP? • WHY THIS PARTNERSHIP HAS BEEN IMPORTANT TO THE BLM ORIGINS AND HISTORY OF DRRP • INITIAL RIPARIAN WORK ON SAN MIGUEL RIVER IN EARLY 2000’S – LED BY TNC, PRECURSOR TO THE DRRP. • 2009 – TNC AWARDED CONTRACT TO TAMARISK COALITION TO DEVELOP A STRATEGY FOR THE DOLORES RIVER (DR-RAP) • 2010 - DR-RAP FINALIZED • 2010 - FIRST MOU SIGNED • 2010 – FIRST BLM ASSISTANCE AGREEMENT • 2012 – AGO BLUE RIVERS DESIGNATION • 2015 – TRANSITION PLAN FINALIZED • 2015 – DOLORES RIVER HEALTHY LANDS FOCAL AREA • 2015 – SECOND MOU SIGNED • 2016 – SECOND BLM ASSISTANCE AGREEMENT DOLORES RIVER RESTORATION ACTION PLAN (DR-RAP) 1. IDENTIFIED A VISION: “A THRIVING DOLORES RIVER SYSTEM THAT IS ECOLOGICALLY, SOCIALLY, AND ECONOMICALLY SUSTAINABLE IN A MULTIUSE CONTEXT.” “A DOLORES RIVER WATERSHED DOMINATED BY NATIVE VEGETATION, WHERE THE THREATS FROM TAMARISK AND OTHER ASSOCIATED INVASIVE SPECIES HAVE BEEN MITIGATED AND THE RIPARIAN AREAS OF THE WATERSHED CONTINUE TO BECOME MORE NATURALLY FUNCTIONING, SELF-SUSTAINING, DIVERSE, AND RESILIENT OVER TIME.” DRRP MANAGEMENT GOALS Significantly increase the number of sustainable, healthy riparian plant Ecologic communities while reducing those dominated by tamarisk and other invasive, non-native plant species. Develop a professional, competitive, and efficient work force; improve Social aesthetic enjoyment;
    [Show full text]
  • Abandonment of Unaweep Canyon (1.4–0.8 Ma), Western Colorado: Effects of Stream Capture and Anomalously Rapid Pleistocene River Incision
    CRevolution 2: Origin and Evolution of the Colorado River System II themed issue Abandonment of Unaweep Canyon (1.4–0.8 Ma), western Colorado: Effects of stream capture and anomalously rapid Pleistocene river incision Andres Aslan1,*, William C. Hood2,*, Karl E. Karlstrom3,*, Eric Kirby4, Darryl E. Granger5,*, Shari Kelley6, Ryan Crow3,*, Magdalena S. Donahue3,*, Victor Polyak3,*, and Yemane Asmerom3,* 1Department of Physical and Environmental Sciences, Colorado Mesa University, Grand Junction, Colorado 81501, USA 2Grand Junction Geological Society, 515 Dove Court, Grand Junction, Colorado 81501, USA 3Department of Earth and Planetary Sciences, University of New Mexico, Northrop Hall 141, Albuquerque, New Mexico 87131, USA 4College of Earth, Ocean and Atmospheric Sciences, Oregon State University, 202D Wilkinson Hall, Corvallis, Oregon 97330, USA 5Department of Earth and Atmospheric Sciences, Purdue University, 550 Stadium Mall Drive, West Lafayette, Indiana 47907, USA 6New Mexico Bureau of Geology and Mineral Resources, New Mexico Institute of Mining and Technology, 801 Leroy Place, Socorro, New Mexico 87801, USA ABSTRACT opment of signifi cant relief between adjacent through resistant Precambrian bedrock (Fig. 2). stream segments, which led to stream piracy. It has no major river at its base, and is currently Cosmogenic-burial and U-series dating, The response of rivers to the abandonment drained by two underfi t streams, East and West identifi cation of fl uvial terraces and lacus- of Unaweep Canyon illustrates how the Creeks, which drain the northeast and southwest trine deposits, and river profi le reconstruc- mode and tempo of long-term fl uvial incision ends of the canyon, respectively. Starting with tions show that capture of the Gunnison are punctuated by short-term geomorphic the Hayden Survey (Peale, 1877), geologists River by the Colorado River and abandon- events such as stream piracy.
    [Show full text]
  • Figure 12B-01. Mountainous Volcanic Region
    108°W 106°W F Ancestral ron t Rang LARIMER Uinta Sand Upl e ift Little Snake River Wash Ba North Platte River MOFFAT s Yampa River in JACKSON Park-Gore Range Axial ROUTT Ba s in Up li h ft rc as A ek e Dougl Cr White River GRAND 40°N Whi EXPLANATION RIO BLANCO 40°N te Ri Neogene Volcanics ver Upli Neogene Sediments ft Paleogene Volcanics Eagle River Blue River Paleocene-Cretaceous Intrusives Piceance Basin Roaring ForkCentral River Colorado TroughEAGLE Cretaceous Seaway Sediment GARFIELD Eagle River Sawatch Range Aquifers SUMMIT Mesozoic Sediment Aquifers Ancestral Rockies Basins Colorado River Precambrian Basement PITKIN Arkansas River East Muddy Creek Mountainous Region MESA LAKE PARK Unc Mountainous Valleys ompa ghre Up Colorado Plateaus Region lif DELTA t Laramide Basin Outlines Laramide Uplift Axis Uncompaghre Uplift G un Taylor River CHAFFEE nison Laramide Basin Axis GUNNISON Upl Ancestral Rockies Uplift Axis Uncompahgre River South Arkansas River ift Ancestral Rockies Basin Axis Paradox Basin FREMONT MONTROSE San Lui CUSTER s OURAY Up San Miguel River li ft 38°N SAN MIGUEL SAGUACHE 38°N Animas River HINSDALE DOLORES SAN JUAN Rio Grande MINERAL ag Dolores River n S West Dolores River ua J RIO GRANDE ALAMOSA e San MONTEZUMA n Dom Jua Archuleta Anticlinorium San Los Pinos River LA PLATA COSTILLA San Juan Piedra River Basin CONEJOS Tusas Uplift COSTILLA ARCHULETA COSTILLA 108°W 106°W 0 10 20 30 40 50 Miles Geology modified from Tweto (1979); structural features from Hemborg (1996). 0 10 20 30 40 50 Kilometers Figure 12b-01.
    [Show full text]
  • River Flow Advisory
    River Flow Advisory Bureau . of Reclamation Upper Colorado Region Salt Lake City, Utah Vol. 15, No. 1 September 1984 River flows in the Upper Colorado River drainage, still high for this time of year, are not expected to decrease much for several weeks: While the daily update of operations and releases has been discontinued, the toll-free numbers now provide updates on Bureau of Reclamation activities and projects. Utah residents may call 1-800-624-1094 and out-of-Utah residents may call 1-800-624-5099. Colorado River at Westwater Canyon The flow of the Colorado River on September 10 was 7, 000 cfs, and is expected to decrease slightly over the next few weeks. Cataract Canyon Includin2 the Green- River The flow was 11,500 cfs on September 10 and will continue to decrease slightly. Lake Powell Lake Powell's elevation on September 10 was 3,699. Assuming normal inflow for this time of year, the lake should continue to go down slowly to elevation 3,682 by next spring. Colorado River through Grand Canyon . Releases through Glen Canyon Dam remain at 25,000 cfs. These releases are expected to be maintained with no daily fluctuations in river flows. Upper Green River - Fontenelle Reservoir Fontenelle Reservoir is now at elevation 6,482 feet. Releases through the dam will be reduced to about 600 cfs starting on September 17 for about 2 weeks during powerplant maintenance. Green River Flows Below Flaming Gorge Dam On September 10 Flaming Gorge Reservoir was at elevation 6,039.9 feet. Releases from the dam are expected to average 2, 500 cfs in September and October with usual daily fluctuations.
    [Show full text]
  • Gunnison River
    final environmental statement wild and scenic river study september 1979 GUNNISON RIVER COLORADO SPECIAL NOTE This environmental statement was initiated by the Bureau of Outdoor Recreation (BOR) and the Colorado Department of Natural Resources in January, 1976. On January 30, 1978, a reorganization within the U.S. Department of the Interior resulted in BOR being restructured and renamed the Heritage Conservation and Recreation Service (HCRS). On March 27, 1978, study responsibility was transferred from HCRS to the National Park Service. The draft environmental statement was prepared by HCRS and cleared by the U.S. Department of the Interior prior to March 27, 1978. Final revisions and publication of both the draft environmental statement, as well as this document have been the responstbility of the National Park Service. FINAL ENVIRONMENTAL STATEMENT GUNNISON WILD AND SCENIC RIVER STUDY Prepared by United States Department of the Interior I National Park Service in cooperation with the Colorado Department of Natural Resources represented by the Water Conservation Board staff Director National Par!< Service SUMMARY ( ) Draft (X) Final Environmental Statement Department of the Interior, National Park Service 1. Type of action: ( ) Administrative (X) Legislative 2. Brief description of action: The Gunnison Wild and Scenic River Study recommends inclusion of a 26-mile (41.8-km) segment of the Gunnison River, Colorado, and 12,900 acres (S,200 ha) of adjacent land to be classified as wild in the National Wild and Scenic Rivers System under the administration of the National Park Service and the Bureau of Land Management, U.S. D. I. This river segment extends from the upstream boundary of the Black Canyon of the Gunnison National Monument to approximately 1 mile (1.6 km) below the confluence with the Smith Fork.
    [Show full text]
  • Pleistocene Drainage Changes in Uncompahgre Plateau-Grand
    New Mexico Geological Society Downloaded from: http://nmgs.nmt.edu/publications/guidebooks/32 Pleistocene drainage changes in Uncompahgre Plateau-Grand Valley region of western Colorado, including formation and abandonment of Unaweep Canyon: a hypothesis Scott Sinnock, 1981, pp. 127-136 in: Western Slope (Western Colorado), Epis, R. C.; Callender, J. F.; [eds.], New Mexico Geological Society 32nd Annual Fall Field Conference Guidebook, 337 p. This is one of many related papers that were included in the 1981 NMGS Fall Field Conference Guidebook. Annual NMGS Fall Field Conference Guidebooks Every fall since 1950, the New Mexico Geological Society (NMGS) has held an annual Fall Field Conference that explores some region of New Mexico (or surrounding states). Always well attended, these conferences provide a guidebook to participants. Besides detailed road logs, the guidebooks contain many well written, edited, and peer-reviewed geoscience papers. These books have set the national standard for geologic guidebooks and are an essential geologic reference for anyone working in or around New Mexico. Free Downloads NMGS has decided to make peer-reviewed papers from our Fall Field Conference guidebooks available for free download. Non-members will have access to guidebook papers two years after publication. Members have access to all papers. This is in keeping with our mission of promoting interest, research, and cooperation regarding geology in New Mexico. However, guidebook sales represent a significant proportion of our operating budget. Therefore, only research papers are available for download. Road logs, mini-papers, maps, stratigraphic charts, and other selected content are available only in the printed guidebooks. Copyright Information Publications of the New Mexico Geological Society, printed and electronic, are protected by the copyright laws of the United States.
    [Show full text]
  • Dolores River Desert Bighorn Sheep Herd (DBS-61) Executive Summary
    Dolores River Desert Bighorn Sheep Herd (DBS-61) Executive Summary GMUs: S-63 (Middle Dolores River) and S-64 (Upper Dolores River) Tier Status: Tier 1 Land Ownership: BLM 45%, Private 29%, USFS 24%, State 2%, 2018 Posthunt Population Estimate: 175 Average Length of Longest Horn (harvested rams): 31 “ Posthunt Population Estimate 300 Dolores River Herd 250 200 150 100 50 0 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 2018 2019 Proposed Objective S63 S64 Dolores Herd Figure 1. DBS-61 posthunt population estimate 1987-2019. Background and Issue Summary: The Dolores River Desert Bighorn sheep herd (DBS-61) is located in southwest Colorado and occupies the canyon country of the Dolores River, and its tributaries, downstream of McPhee Reservoir. It consists of Game Management Units (GMUs) S-63 (Middle Dolores River) and S-64 (Upper Dolores River). The majority of the occupied bighorn habitat occurs on lands managed by the Bureau of Land Management (BLM). DBS-61 is a Tier 1 bighorn population and should be given the highest priority for inventory, habitat protection and improvement, disease prevention and research. Although bighorn sheep were likely indigenous, none were present in the past century. The current population was established beginning in 1986 with the release of 25 bighorn from Arizona. There have been a total of four transplants of desert bighorn into the Dolores Canyon. Population sources have been from Arizona (source for two transplants), Nevada, and Utah.
    [Show full text]
  • Executive Summary U.S
    Glen Canyon Dam Long-Term Experimental and Management Plan Environmental Impact Statement PUBLIC DRAFT Executive Summary U.S. Department of the Interior Bureau of Reclamation, Upper Colorado Region National Park Service, Intermountain Region December 2015 Cover photo credits: Title bar: Grand Canyon National Park Grand Canyon: Grand Canyon National Park Glen Canyon Dam: T.R. Reeve High-flow experimental release: T.R. Reeve Fisherman: T. Gunn Humpback chub: Arizona Game and Fish Department Rafters: Grand Canyon National Park Glen Canyon Dam Long-Term Experimental and Management Plan December 2015 Draft Environmental Impact Statement 1 CONTENTS 2 3 4 ACRONYMS AND ABBREVIATIONS .................................................................................. vii 5 6 ES.1 Introduction ............................................................................................................ 1 7 ES.2 Proposed Federal Action ........................................................................................ 2 8 ES.2.1 Purpose of and Need for Action .............................................................. 2 9 ES.2.2 Objectives and Resource Goals of the LTEMP ....................................... 3 10 ES.3 Scope of the DEIS .................................................................................................. 6 11 ES.3.1 Affected Region and Resources .............................................................. 6 12 ES.3.2 Impact Topics Selected for Detailed Analysis ........................................ 6 13 ES.4
    [Show full text]
  • Management of the Colorado River: Water Allocations, Drought, and the Federal Role
    Management of the Colorado River: Water Allocations, Drought, and the Federal Role Updated March 21, 2019 Congressional Research Service https://crsreports.congress.gov R45546 SUMMARY R45546 Management of the Colorado River: Water March 21, 2019 Allocation, Drought, and the Federal Role Charles V. Stern The Colorado River Basin covers more than 246,000 square miles in seven U.S. states Specialist in Natural (Wyoming, Colorado, Utah, New Mexico, Arizona, Nevada, and California) and Resources Policy Mexico. Pursuant to federal law, the Bureau of Reclamation (part of the Department of the Interior) manages much of the basin’s water supplies. Colorado River water is used Pervaze A. Sheikh primarily for agricultural irrigation and municipal and industrial (M&I) uses, but it also Specialist in Natural is important for power production, fish and wildlife, and recreational uses. Resources Policy In recent years, consumptive uses of Colorado River water have exceeded natural flows. This causes an imbalance in the basin’s available supplies and competing demands. A drought in the basin dating to 2000 has raised the prospect of water delivery curtailments and decreased hydropower production, among other things. In the future, observers expect that increasing demand for supplies, coupled with the effects of climate change, will further increase the strain on the basin’s limited water supplies. River Management The Law of the River is the commonly used shorthand for the multiple laws, court decisions, and other documents governing Colorado River operations. The foundational document of the Law of the River is the Colorado River Compact of 1922. Pursuant to the compact, the basin states established a framework to apportion the water supplies between the Upper and Lower Basins of the Colorado River, with the dividing line between the two basins at Lee Ferry, AZ (near the Utah border).
    [Show full text]
  • Navajo Reservoir and San Juan River Temperature Study 2006
    NAVAJO RESERVOIR AND SAN JUAN RIVER TEMPERATURE STUDY NAVAJO RESERVOIR BUREAU OF RECLAMATION 125 SOUTH STATE STREET SALT LAKE CITY, UT 84138 Navajo Reservoir and San Juan River Temperature Study Page ii NAVAJO RESERVOIR AND SAN JUAN RIVER TEMPERATURE STUDY PREPARED FOR: SAN JUAN RIVER ENDANGERED FISH RECOVERY PROGRAM BY: Amy Cutler U.S. Department of the Interior Bureau of Reclamation Upper Colorado Regional Office FINAL REPORT SEPTEMBER 1, 2006 ii Navajo Reservoir and San Juan River Temperature Study Page iii TABLE OF CONTENTS EXECUTIVE SUMMARY ...............................................................................................1 1. INTRODUCTION......................................................................................................3 2. OBJECTIVES ............................................................................................................5 3. MODELING OVERVIEW .......................................................................................6 4. RESERVOIR TEMPERATURE MODELING ......................................................7 5. RIVER TEMPERATURE MODELING...............................................................14 6. UNSTEADY RIVER TEMPERATURE MODELING........................................18 7. ADDRESSING RESERVOIR SCENARIOS USING CE-QUAL-W2................23 7.1 Base Case Scenario............................................................................................23 7.2 TCD Scenarios...................................................................................................23
    [Show full text]
  • Wild and Scenic Rivers
    Analysis of the Management Situation Moab BLM Field Office CHAPTER 17 – WILD AND SCENIC RIVERS 17.1 RESOURCE OVERVIEW The Wild and Scenic Rivers Act of 1968 (WSRA) established legislation for a National Wild and Scenic Rivers System (NWSRS) to protect and preserve designated rivers throughout the nation in their free- flowing condition and to protect and preserve their immediate environments. The WSRA includes policy for managing designated rivers and created processes for designating additional rivers for the NWSRS. Section 5(d) of the Act directs federal agencies to consider the potential for national wild, scenic, and recreational river areas in all planning for the use and development of water and related land resources. A wild and scenic river (WSR) review is being conducted as part of the current Bureau of Land Management (BLM), Moab Field Office (FO) resource management planning process. The first phase of the WSR review is to inventory all potentially eligible rivers within the planning area to determine which of those rivers are eligible for consideration as part of the NWSRS. To be eligible, rivers must be free-flowing and possess at least one outstandingly remarkable value (ORV). ORVs are evaluated in the context of regional and/or national significance and must be river-related. Each river/segment determined to be eligible is then given a tentative classification based on the current level of human development associated with that river/segment. In the second phase of the WSR review, eligible rivers are taken through the land use planning process of the resource management plan (RMP) to determine their "suitability" for designation as WSRs.
    [Show full text]
  • Gunnison-Dolores River Watershed
    United States Department of Agriculture - Colorado Natural Resources Conservation Service Gunnison-Dolores Rivers The Gunnison- Dolores Rivers Watershed Watershed totals 6,014,600 acres. Resources at work from October 1, 2010 - September 30, 2011 It includes all or por- tions of Delta, Gunni- son, Hinsdale, Mon- trose, Ouray, The Colorado Watershed Approach Saguache, and San Miguel Counties. Instead of the traditional statewide approach in NRCS natural resource addressing priority resource issues like soil erosion, specialists are staffed at the Delta, Gunnison, water quality, grazing lands, wildlife, and animal waste, and Montrose USDA NRCS looks to Colorado’s ten watersheds to identify their Field Service Centers to provide technical particular local resource needs and priorities. assistance to watershed residents. Watershed work groups meet annually to determine which NRCS Vision natural resource concerns are most prevalent in their Productive Lands - Healthy Environment communities. In turn, Colorado NRCS focuses its resources on NRCS Mission Helping People addressing those concerns. Colorado’s local Help the Land conservation districts provide leadership in this effort to foster increased decision making at the local level. www.co.nrcs.usda.gov High Priority Resource Concerns in the Gunnison-Dolores Rivers Watershed • Water Quantity • Water Quality • Rangeland Health • Invasive Species • Erosion Helping People Help the Land Watershed Profile Fiscal Year 2011 Environmental Quality Incentives Program Summary Applications Contracts
    [Show full text]