United States Department of the Interior U. S. GEOLOGICAL SURVEY NEVADA WATER SCIENCE CENTER 160 North Stephanie Street Henderson, Nevada 89074 April 18, 2017 U.S. Fish and Wildlife Service Attention: Daniel Russell 2800 Cottage Way, Room W-2606 Sacramento, CA 95825 Dear Dr. Russell: I have reviewed the 2017 Draft Species Status Assessment for 14 Nevada Springsnails. Overall, I found this SSA to be informative and well-written. Some information was repeated, which could be condensed into an appendix (i.e. Tetratech 2012) unless it is desired that each section is to be stand-alone. Of particular note, Manse Spring is flowing and has been flowing for at least several years, although it did go dry at one point in the 1970s. I do not know exactly when it began flowing again, but USGS measurements at the site as recently as 2011 can be obtained at this URL: https://waterdata.usgs.gov/nwis/measurements/?site_no=360919115541501 My other comments are contained within the Track Changes version of the text. Thank you for the opportunity to review this SSA. Sincerely, /s/ Megan E. Poff Supervisory Hydrologist, USGS Nevada Water Science Center COVER PAGE TITLE PAGE ACKNOWLEDGEMENTS TABLE OF CONTENTS CONTENTS 1 Introduction ........................................................................................................................... 13 2 Analysis Framework ............................................................................................................. 14 2.1 Analysis Area ................................................................................................................. 14 2.2 Overview of Springsnail Resiliency, Redundancy, and Representation ........................ 16 2.3 Methodology .................................................................................................................. 17 3 Species Needs ....................................................................................................................... 20 3.1 Springsnail Biogeography, Biology, and Habitat........................................................... 20 3.1.1 Range and Distribution ........................................................................................... 20 3.1.2 Biology and Life History ........................................................................................ 21 3.2 Spring Characteristics and Function .............................................................................. 26 3.3 Physical and Biological Needs of Springsnails .............................................................. 28 3.3.1 Adequate Water Quality ......................................................................................... 28 3.3.2 Aquatic Vegetation and Substrate ........................................................................... 29 3.3.3 Free-Flowing Water ................................................................................................ 30 4 Current Conditions—Factors That May Impact Species Needs ........................................... 31 4.1 Water Management ........................................................................................................ 31 4.2 Stressors and Sources of Stressors ................................................................................. 38 4.2.1 Considered but not Carried Forward....................................................................... 38 4.2.2 Considered and Carried Forward ............................................................................ 38 4.3 Land Management and Conservation Plans ................................................................... 59 4.4 Cumulative Effects ......................................................................................................... 60 4.5 Summary ........................................................................................................................ 60 5 Current Conditions—Springsnail Habitat and Populations .................................................. 61 5.1 Las Vegas Valley HA (212) and Pahrump Valley HA (162) – Springs and Spring Provinces and Current Habitat Conditions ............................................................................... 62 5.1.1 Corn Creek Springs Province, Southeast of Corn Creek Spring, Unnamed Spring near Corn Creek Springs ....................................................................................................... 63 5.1.2 Willow Spring ......................................................................................................... 66 5.1.3 Red Spring .............................................................................................................. 67 5.1.4 Crystal Spring ......................................................................................................... 71 5.1.5 Horse Springs Province........................................................................................... 71 5.1.6 Kiup Spring ............................................................................................................. 73 5.1.7 Manse Spring .......................................................................................................... 74 5.1.8 South Rainbow Springs........................................................................................... 74 5.2 Las Vegas and Pahrump Valleys – Springsnail Species and Current Population Conditions ................................................................................................................................. 75 5.2.1 Spring Mountains pyrg ........................................................................................... 75 5.2.1 Corn Creek pyrg ...................................................................................................... 78 5.3 Muddy River Springs Area HA (219), Black Mountains Area HA (215), and Pahranagat Valley HA (209) – Springs and Spring Provinces and Current Habitat Conditions ................. 81 5.3.1 Cardy Lamb Spring ................................................................................................. 82 5.3.2 Baldwin Spring ....................................................................................................... 84 5.3.3 Muddy Spring ......................................................................................................... 87 5.3.4 Apcar Springs Province .......................................................................................... 89 5.3.5 Plummer Springs Province ..................................................................................... 93 5.3.6 Pederson Springs Province ..................................................................................... 96 5.3.7 Blue Point Spring .................................................................................................. 101 5.3.8 Ash Springs Province ............................................................................................ 105 5.3.9 Crystal Springs Province....................................................................................... 108 5.3.10 Hiko Spring ........................................................................................................... 110 5.4 Muddy River Springs Area, Black Mountains Area, and Pahranagat Valley – Springsnail Species and Current Population Conditions ........................................................ 111 5.4.1 Moapa pebblesnail ................................................................................................ 111 5.4.2 Moapa Valley pyrg ............................................................................................... 114 5.4.3 Grated Tryonia ...................................................................................................... 117 5.4.4 Blue Point Pyrg ..................................................................................................... 121 5.4.5 Hubbs Pyrg............................................................................................................ 122 5.4.6 Pahranagat Pebblesnail ......................................................................................... 125 5.5 White River Valley HA (207), Cave Valley HA (180), and Lake Valley HA (183) – Springs and Spring Provinces and Current Habitat Conditions .............................................. 128 5.5.1 Camp Spring ......................................................................................................... 129 5.5.2 Moon River Spring ............................................................................................... 130 5.5.3 Hot Creek Springs Province.................................................................................. 132 5.5.4 Flag Springs Province ........................................................................................... 134 5.5.5 Butterfield Spring Province .................................................................................. 136 5.5.6 Silver Springs Province......................................................................................... 139 3 5.5.7 Moorman Spring ................................................................................................... 140 5.5.8 Emigrant Spring Province ..................................................................................... 142 5.5.9 Hardy Spring Province .......................................................................................... 146 5.5.10 Parker Station Spring ...........................................................................................