North Concho River Watershed
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~- Prepared by the: Uppe-r Colomdo Rive-r Authwit4 Brush Control Planning, Assessment ~ f=easiblity S-tudy Upper Colorado River Authority • Final Report amended January 1999 N_Q_r~b____ QQ-n:~bQ ____~i~~--r ____ ~_gJ;_~r:§_b~~-- BRusl-l CONTROL PLANNING. ASSt:;;SSMt:;;NT &.l=t:;;ASIBILITY STUDY TABLE OF CONTENTS • ACKNOWLEDGMENTS • 1.0 INTRODUCTION .................................................................... page 2 • 2.0 EXECUTIVE SUMMARY........................................................ page 4 • 3.0 HYDROLOGIC EVALUATION ................................................ page 11 3.1 Description of the Watershed 3.2 Historical Considerations 3.21 Ecological History 3.22 Hydrological History 3.3 Geological Considerations 3.4 Existing Surface Water Hydrology 3.5 Existing Groundwater Hydrogeology 3.6 Description of the Watershed Hydrologic System 3. 7 Hydrologic Evaluation Summary & Conclusions • 4.0 DATABASE AND GIS DEVELOPMENT.. ............................... page 34 ANALYSIS OF WATERSHED MODELING • 5.0 ECONOMIC ANALYSIS ......................................................... page 50 • 6.0 PROGRAM IMPLEMENTATION ............................................ page 56 • LIST OF TABLES ............................................................................. page 60 • LIST OF FIGURES ........................................................................... page 63 • LIST OF PLATES ............................................................................. page 66 ~CKNOWLEDGMENTS The preparation of this report is the result of more than a dozen state, federal and local entities uniting under a common brush control banner lo marshal all possible resources which would develop data conclusions and recommendations for feasible and practical means of providing water for the North Concho River Watershed. The catalyst for this cooperation is due to State Representative Robert /unel/ and his efforts to tmite all parties into a common goal. Special thanks are also due to Craig Pedersen, Executive Administrator of the Texas Water Development Board for support of tl1is project. In addition, more than forty individuals have been involved in the preparation of the report and include: John Walker Stephen Brown johnny Oswald Darrell Ueckert Fred Teagarden ]ames Moore Stan Reineke Ellen Groth Darwin Schrader Tim Reineke C. Skeete Foster J.P. Bach Mark Ramirez Ruby Gutierrez Richard Conner Chad Chadbourne /effie Roberts F. Charles Baird Scott Durham Ray Alderman Steven T. Bednarz Gary Grogan Dorris Sonnenberg William A. Dugas, Jr. Bob Jennings Ralph Hoelscher Lee Miller David Rawlings Hope Huffman Tim]. Dyba/a Reed johnson Jack Brewer Hugh L. Stone Bi/1 Barber Fred Campbell Tim R. Turner Cliff Caldwell Billy Johnston George Barnham Sisco Jr. Jeff Copeland Matthew G. Bisson Larry Glass Gary Foster Craig Demere Lonnie Horwood Winn McClure Reed Stewart Frank Price Mackey McEntire Nort.b Concbo River W at,ersbell --------------------------------------------------------------------------------------------------- 8RUSl-l CONTROL PLANNING. ASS!;SSMGNT &. J=GAS/8/L/TY STUDY INTRODUCTION 1.0 During the last 35 years, stream flow on the North Concho River has decreased to less than 22% of that of the previous 35 years, even though average annual rainfall has increased slightly in the same period. Records and historical accounts indicate that the North Concho River and its main tributaries generally experienced continuous perennial flows from 1925 to 1959 . Official USGS stream measuring stations immediately north of San Angelo recorded a total of 1,351,593 acre feet of water stream flow during that period for an average of 38,617 acre feet of water per year. Annual average rainfall at the measuring station was 19.48 inches for that same period. From 1960 through 1996 a total of 309,255 acre feet of water stream flow was recorded (or an average of 8,358 acre feet per year). Average annual rainfall from 1960 through 1996 was 20.31 inches. The North Concho River and its tributaries have ceased to have perennial continuous flow. The river and its tributaries have evolved into small areas of water impoundments replenished solely by major storm events and minor sporadic stream flow. There may be several factors contributing to the decrease in stream flow during this comparison period. Infestation of noxious brush, which has robbed and is continuing to degrade the underground aquifers, may account for a major portion of the decreased flow on the North Concho River watershed. This study has been executed to document the role of brush control in watershed restoration. The watershed of the North Concho River and its main tributaries consists of approximatley 950,000 acres, much of which has become infested with brush. It is believed that brush has robbed the underground aquifers of their once prolific outcrop springs. This has resulted in a drastic reduction in average annual stream flow in the river and subsequently into the only reservoir on the watershed--O.C. Fisher. As a consequence of the diminished North Concho River stream flow, landowners in the watershed have experienced water shortages, major degradation of underground aquifers (causing irrigation practices to be limited), deteriorated 2 water quality, annihilated aquatic habitats and steadily decreased public water supplies for a reservoir intended to sustain a major metropolitan center of Texas. In an effort to determine the exact damage noxious brush caused on the North Concho River watershed, as well as to evaluate methods and procedures for eradication or removal of certain areas of heavily infested brush, several entities have united into a compact. These entities have been assisted by additional state and federal agencies to undertake this comprehensive study. This assessment will provide the Texas Water Development Board and the people of Texas with means, procedures, and recommendations of how to recapture and utilize water, now being stolen, for increased public benefit on an entire watershed. 3 XECUTIVE SUMMARY 2.0 The rapid depletion of water resources in Texas due to urban growth, agriculture, industrial and other increased uses requires and demands that state government take immediate and decisive steps toward developing, saving, enhancement and utilization of existing known water sources that are now being robbed from the people of Texas by non- productive and noxious brush. Nowhere is that thievery more apparent than in an already water poor West Texas ..... and specifically the North Concho River watershed, which encompasses more than 950,000 acres. There are more than 130 million mesquite trees and 100 million juniper trees which have tentacle roots serving as straws sucking water from the North Concho River watershed. The potential transpiration by mesquite and juniper on this watershed is to rob almost 2 million acre feet of water annually from productive use. By way of contrast, mesquite and juniper on the North Concho watershed use 100 times more water than the City of San Angelo uses annually. Therefore, the objective of this study is to recapture some of this water which is being needlessly wasted. The North Concho River Watershed Brush Control Study is the result of a year-long cooperative study of the watershed, detailing its history, hydrology, geology, land use, past and present characteristics. It makes dynamic and conclusive recommendations which call for immediate action from state government, political subdivisions and landowners to initiate an action program which will result in removal of mesquite and juniper and restore underground aquifers and natural stream flow for public benefit. The study was accomplished through a partnership composed of the Upper Colorado River Authority, Texas A&M Research & Extension Center and The Texas State Soil & Water Conservation Board through a grant obtained through the Texas Water Development Board. In addition, other participants include the Texas Parks & Wildlife Department, U.S.D.A. Natural Resources Conservation Service, Blackland Research Center, and Soil & Water Conservation Districts from Tom Green, Coke, Sterling and Glasscock County. The following pages of this executive summary outline the study and program, its effects, costs, implementation and administration. The text and graphics show the detail, methodology and procedures utilized in finalizing recommendations and conclusions. However, the paramount conclusion flowing through the report is that with successful brush control on the watershed, stream flow in the North Concho river can increase five times over the current amount, underground aquifers can be recharged and water for the people of Texas made available at a cost to the state a fraction of the cost of what a West Texas city or individual pays for water. 4 •----------------------------------------Estimated-Effects-otBrush-£-ontrol-cn-Water-Yfeld- Prior to simulation of stream flow in the North Concho River, a Geographic Information System (GIS) was developed to characterize the area and provide inputs for the simulation model. Data layers in the GIS included soils, topography, climate and vegetation type. The present amount of land in different vegetation types was determined using satellite imagery that was ground truthed for accuracy. The vegetation types and amounts of acreage of primary interest to this study were heavy cedar- 110,508 acres; heavy mesquite- 155,896 acres; moderate mesquite- 92, 735 acres; and light brush- 73,346 acres. Thus a total of 432,485 acres or 45% of the watershed