Alamosa River Watershed Plan

• Document ID: 0001
• County: Rio Grande
• County: Conejos
• County: Costilla
• County: Saguache
• Stream Name: Alamosa River
• Basin: Rio Grande
• Sub-Basin: Alamosa-Trinchera 13010002
• Water Division: 3
• Title: Alamosa River Watershed Restoration Master Plan and Environmental Assessment
• Date: 7/1/2005
• Prepared For: CWCB
• Prepared By: MWH
• Watershed Pro - Doc Type: Planning Report

Figure 2 -51. Total Iron Concentration below Terrace Reservoir and Gomez Bridge by Month ........................... 2-60
Figure 2 -52. Box and Whisker Plot Schematic ................................................................................................................2-61
Figure 2 -53. Regulatory Stream Segments alamosa River Watershed ........................................................................ 2-63
Figure 2 -54. Dissolved Copper Concentrations in Reynolds Adit by Year ................................................................ 2-66
Figure 2 -55. Water Quality Downstream of Summitville by Year - pH ..................................................................... 2-67
Figure 2 -56. Water Quality Downstream of Summitville by Year -Dissolved Copper .......................................... 2-68
Figure 2 -57. Water Quality Downstream of Summitville by Year -Dissolved Zinc ............................................... 2-69
Figure 2 -58. Water Quality Downstream of Summitville by Year -Total Iron ........................................................ 2-70
Figure 2 -59. Water Quality Downstream of Summitville by Year -Dissolved Manganese .................................... 2-71
Figure 2 -60. Water Quality Downstream of Summitville by Year -Dissolved Aluminum ..................................... 2-72
Figure 2 -61. Water Quality in alamosa River Mainstem Following SCMCI; pH, Cu, Zn, Fe ................................2-73
Figure 2 -62. Water Quality in Alamosa River Mainstem Following SCMCI; Mn, Al, Pb, Cd ................................ 2-74
Figure 2 -63. Current Water Quality in alamosa River Mainstem; pH, Cu, Zn, Fe ...................................................2-77
Figure 2 -64. Current Water Quality in alamosa River Mainstem; Mn, Al, Pb, Cd ...................................................2-78
Figure 2 -65. Current Water Quality for Alamosa River Tributaries; pH, Cu, Zn, Fe ...............................................2-81
Figure 2 -66. Current Water Quality for Alamosa River Tributaries; Mn, Al, Pb, Cd ............................................... 2-82
Figure 2 -67. Seasonal Water pH for Alamosa River and Tributaries .......................................................................... 2-84
Figure 2 -68. Seasonal Copper Concentrations for Alamosa River and Tributaries .................................................. 2-85
Figure 2 -69. Seasonal Zinc Concentrations for Alamosa River and Tributaries ....................................................... 2-86
Figure 2 -70. Seasonal Iron Concentrations for alamosa River and Tributaries ........................................................2-87
Figure 2 -71. Seasonal Aluminum Concentrations for alamosa River and Tributaries ............................................2-88
Figure 2 -72. Concentrations of Total Suspended Solids in Mainstem and Tributaries ............................................ 2-92
Figure 2 -73. Year 2003 Water Treatment Plant Influent and Effluent Water Quality ............................................. 2-93
Figure 2 -74. Hydrogeologic Units of the San Luis Valley ............................................................................................. 2-96
Figure 2 -75. Transmissivity of the Unconfined Aquifer, San Luis Valley ................................................................ .. 2-97
Figure 2 -76. Water Table of the Unconfined Aquifer of the San Luis Valley, Late 1996-Early 1997 ...................2-98
Figure 2 -77. Decline in Water Levels in the San Luis Valley ...................................................................................... 2-100
Figure 2 -78. RGDSS Model Target Well Location Map ............................................................................................. 2-102
Figure 2 -79. area-Elevation-Capacity Curve for Terrace Reservoir ........................................................................ 2-105
Figure 2 -80. Terrace Reservoir Plan View ..................................................................................................................... 2-106
Figure 2 -81. Infrared Aerial Photo of Terrace Reservoir Dam, Spillway, and Control Building .......................... 2-106
Figure 2 -82. Terrace Reservoir Spillway from Downstream ....................................................................................... 2-107
Figure 2 -83. Terrace Reservoir South abutment and Spillway from Downstream ................................................ 2-108
Figure 2 -84. Condition of Terrace Reservoir Spillway Concrete and Masonry Approach Walls .......................... 2-108
Figure 2 -85. Terrace Reservoir Discharge Portal and access Tunnel ....................................................................... 2-109
Figure 2 -86. Terrace Reservoir Inlet Structure and Collapsed Trash Racks ............................................................. 2-110
Figure 2 -87. Terrace Reservoir Inlet Structure with New Beams and Trash Racks ................................................2-110
Figure 2 -88. Gate Valve Chamber in Tunnel ................................................................................................................ 2-111
Figure 2 -89. Howell-Bunger Valve at Outlet ................................................................................................................ 2-111
Figure 2 -90. Total versus Dissolved Metal Concentrations in Terrace Reservoir, 1998 to 2001 .......................... 2-116
Figure 2 -91. Location of Terrace Reservoir Sediment Samples ................................................................................. 2-119
Figure 2 -92. Sediment Sample Locations ....................................................................................................................... 2-122
Figure 2 -93. Photo of alum Creek Channel Showing High Sediment Load ........................................................... 2-124
Figure 2 -94. Upper Watershed Sediment Distribution Curves ................................................................................... 2-124
Figure 2 -95. Photo of the Pass Me By Mine Spoils Pile .............................................................................................. 2-125
Figure 2 -96. Photo of Terrace Sediments Deposited Near USGS Gage in 2003 2004 ......................................... 2-126
Figure 2 -97. Middle Watershed Sediment Distribution Curves ................................................................................. 2-127
Figure 2 -98. Lower Watershed Sediment Distribution Curves .................................................................................. 2-128
Figure 2 -99. Sediment Aluminum and Iron Concentrations in the Alamosa River ................................................ 2-130
Figure 2 -100. Sediment Zinc and Copper Concentrations in the alamosa River ................................................... 2-131
Figure 2 -101. Sediment Cadmium, arsenic, Lead, and Nickel Concentrations in the Alamosa River ................ 2-131
Figure 2 -102. Dead Cottonwood Trees in Riparian Corridor .................................................................................... 2-135
Figure 2 -103. Location of Dead Cottonwood Trees .................................................................................................... 2-136
Figure 2 -104. Diversions and Irrigated Areas ................................................................................................................ 2-155
Alamosa River Watershed Restoration Master Plan and Environmental Assessment Page viii