Blackfoot River Tmdl Waterbody Assessment and Total Maximum Daily Load
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BLACKFOOT RIVER TMDL WATERBODY ASSESSMENT AND TOTAL MAXIMUM DAILY LOAD Prepared by Idaho Department of Environmental Quality Pocatello Regional Office 224 South Arthur Avenue Pocatello, ID 83204 December 2001 Table of Contents List of Figures .................................................................................................................................iii List of Tables...................................................................................................................................iv Abbreviations, Acronyms, and Symbols.......................................................................................viii Metric-English Unit Conversions...................................................................................................xii 1 Executive Summary.....................................................................................................................1 2 Blackfoot River Subbasin Description.......................................................................................11 2.1 General........................................................................................................................11 2.1.1 Watershed Characteristics............................................................................20 2.1.2 Cultural Characteristics................................................................................27 2.2 Water Quality Concerns & Status ...............................................................................33 2.2.1 Water Quality Limited Segments Occurring in the Subbasin......................33 2.2.2 Applicable Water Quality Standards............................................................37 2.2.3 General Water Quality Summary.................................................................39 Below Blackfoot Reservoir........................................................................39 Above Blackfoot Reservoir........................................................................43 Blackfoot Reservoir....................................................................................44 2.2.4 Summary and Analysis of Existing Water Quality Data..............................48 Flow Alteration..........................................................................................48 Sediment.....................................................................................................50 Nutrients.....................................................................................................57 Organics .....................................................................................................60 Metals.........................................................................................................60 Temperature ...............................................................................................62 Dissolved Oxygen......................................................................................64 Bacteria.......................................................................................................65 Unknown....................................................................................................67 2.2.5 Summary......................................................................................................67 2.2.6 Streams Fully Supporting Beneficial Uses...................................................67 2.3 Summary of Past and Present Pollution Control Efforts.............................................70 2.3.1 Water Quality Improvement.........................................................................72 3 Blackfoot River Loading Analysis.............................................................................................73 3.1 General........................................................................................................................73 3.1.1 Reasonable Assurance..................................................................................73 3.2 Pollutant Standards / Targets and Load Analysis........................................................74 3.2.1 Sediment.....................................................................................................75 Standard......................................................................................................75 Target.........................................................................................................75 i Discussion..................................................................................................75 Loading Analysis........................................................................................79 3.2.2 Nutrients.....................................................................................................98 Standard......................................................................................................98 Target.........................................................................................................98 Discussion..................................................................................................98 Loading Analysis......................................................................................104 3.2 Summary of Data Needs ...........................................................................................115 Glossary........................................................................................................................................116 Literature Cited ............................................................................................................................139 Appendices Appendix A: State of Idaho Water Quality Standards....................................................149 Appendix B: Proper Functioning Condition Information...............................................151 Appendix C: Stream Sediment Information....................................................................157 Appendix D: Water Quality Information........................................................................164 Appendix E: Nutrient Information..................................................................................186 Appendix F: USGS Water Quality Information..............................................................194 Appendix G: Dry Valley Creek Information...................................................................209 Appendix H: Angus Creek Flow Information.................................................................213 Appendix I: USGS Nutrient Information........................................................................215 ii List of Figures Figures 1-1 Land ownership and 303(d)-listed waterbodies...................................................................2 2.1-1 Blackfoot River subbasin...................................................................................................12 2.1-2 Weighted average soil slope in the Blackfoot River subbasin...........................................14 2.1-3 Weighted average K-factor (soil erosion capability) in the Blackfoot River subbasin. Soil erosion capability increases as K-factor increases.....................................15 2.1-4 Hydrographs at USGS surface-water stations near Shelley (13066000) and Henry (13063000) and projected natural hydrograph near Shelley (from USGS Water Resources Data reports).....................................................................................................19 2.1-5 Land ownership in the Blackfoot River subbasin..............................................................28 2.1-6 Land use in the Blackfoot River subbasin (from Idaho Department of Water Resources Geographic Information System, 1991).................................................30 2.2-1 Blackfoot River subbasin 303(d)-listed waterbodies and pollutants..................................36 G-1 Relationship between turbidity and total suspended solids data collected simultaneously in Dry Valley Creek from all sites, 1989-1999. (Sample collected at DV-7 on 08/25/1977 questioned and was eliminated from dataset; values below minimum detection limit assigned a value of ½ detection limit; N=219, R2 =0.843, p<0.001.)..................................................................211 G-2 Relationship between turbidity and total suspended solids data collected simultaneously in Maybe Canyon Creek near the mouth, 1989-1998. (Values below minimum detection limit were assigned a value of ½ detection limit; N=33, R2 =0.897, p<0.001.)....................................................................212 iii List of Tables Tables 1-1 Targets used to establish pollutant load allocations for 303(d)-listed streams in the Blackfoot River subbasin...........................................................................................4 1-2 Water quality limited segments in the Blackfoot River subbasin on the 303(d) list including listed pollutants and mass per unit time (tons/year) pollutant load allocations and reductions....................................................................................................6 2.1-1 Characteristics of ecoregions in the Blackfoot River subbasin (modified from Maret et al. 1997 and Omernik and Gallant 1986)....................................................13 2.1.2 Monthly average temperatures (Fahrenheit) at Blackfoot and Henry National Weather Service stations (from Western Regional Climate Center, internet communication)..................................................................................................................17