Marissa L. Wulff Brock M. Huntsman Jeff L. Gronemyer Jordan M. Buxton 20260107 tabular digital data https://www.sciencebase.gov U.S. Geological Survey U.S. Geological Survey data release https://doi.org/10.5066/P1Z7RCRC Marissa L Wulff 20251222 publication https://www.sciencebase.gov US Geological Survey U.S. Geological Survey, 2025, Native Fish Population and Habitat Studies, Santa Ana River, California: U.S. Geological Survey data release collection, https://doi.org/10.5066/P9W7SV9M. [Updated periodically.] Accessed 22Dec2025. https://www.sciencebase.gov/catalog/item/63360a12d34e900e86c8e611 This dataset includes fish population and habitat data collected in 2025 to support development of the upper Santa Ana River Habitat Conservation Plan for the Santa Ana Sucker (Catostomus santaanae) and the Arroyo Chub (Gila orcuttii) in the Santa Ana River, California. Collection of additional data on the Santa Ana Sucker and the Arroyo Chub has been identified as a needed task to support development of the upper Santa Ana River (SAR) Habitat Conservation Plan (HCP; http://www.uppersarhcp.com). The ability to monitor population abundance and understanding the habitats used by species are important when developing such plans. The Santa Ana Sucker is listed as a threatened species under federal legislation and is considered a species of special concern in California by the California Department of Fish and Wildlife (Moyle, 2002). The Arroyo Chub is also considered a species of special concern in California by the California Department of Fish and Wildlife (Moyle, 2002). Both species are present in the Santa Ana River watershed in the area being evaluated for establishment of the upper Santa Ana River Habitat Conservation Plan. The HCP is a collaborative effort involving the water resource agencies of the Santa Ana River Watershed, the US Fish and Wildlife Service, California Department of Fish and Wildlife, and other government agencies and stakeholder organizations. The goals of the HCP are to: 1) enable the water resource agencies to provide a reliable water supply for human uses; 2) conserve and maintain natural rivers and streams that provide habitat for a diversity of unique and rare species; and 3) maintain recreational opportunities for activities such as hiking, fishing, and wildlife viewing, provided by the protection of these habitats and the river systems they depend on. The HCP will specify how species and their habitats will be protected and managed in the future and will provide the incidental take permits needed by the water resource agencies under the federal and state endangered species acts to maintain, operate, and improve their water resource infrastructure. Although the Santa Ana Sucker has been the subject of various research and monitoring studies within its remaining habitat in California, initial assessment of the available data within the HCP suggested that additional data on population size, fish habitat use, and availability of suitable habitat would be needed to support development of the HCP. Similarly, work on the Arroyo Chub has been limited and there is little data on the species within the HCP area, particularly the mainstem Santa Ana River. Thus, the collection of additional data on these two species has been identified as a needed task to support development of the HCP. The goals of the current study are: 1) Compare snorkeling and electrofishing as methods for estimating native fish abundance; 2) Develop a population estimate for native fish species in the study area based on the results from Goal 1, and 3) Develop a habitat suitability model for the Santa Ana River for Santa Ana Sucker, and if possible, Arroyo Chub. 20250902 20250918 ground condition Complete Annually Upper Santa Ana River, Riverside County, California, USA -117.46530 -117.35244 34.04780 33.96340 ISO 19115 Topic Category biota None Santa Ana Sucker (Catostomus santaanae) population estimate habitat use Arroyo Chub (Gila orcuttii) USGS Thesaurus ichthyology wildlife population management habitats USGS Metadata Identifier USGS:691cfba0d4be021d1d89b496 Geographic Names Information System (GNIS) California Riverside County Santa Ana River Integrated Taxonomic Information System (ITIS, www.itis.gov) Gila orcuttii Catostomus santaanae Kingdom Animalia animals Subkingdom Bilateria Infrakingdom Deuterostomia Phylum Chordata chordates Subphylum Vertebrata vertebrates Infraphylum Gnathostomata Superclass Actinopterygii ray-finned fishes spiny rayed fishes Class Teleostei Superorder Ostariophysi Order Cypriniformes minnows suckers Superfamily Cyprinoidea Family Leuciscidae Genus Gila western chubs Species Gila orcuttii arroyo chub Superfamily Cobitoidea Family Catostomidae suckers Subfamily Catostominae Tribe Catostomini Genus Pantosteus mountain suckers Species Pantosteus santaanae Santa Ana Sucker None. Please see 'Distribution Information' section for details. These data are marked with a Creative Commons Zero v1.0 Universal (CC0-1.0) public domain dedication and do not have any use constraints. Users are advised to read the dataset's metadata thoroughly to understand appropriate use and data limitations. It is requested that the suggested citation for this USGS data release be included in any publications that reference or utilize these data. Brock M Huntsman U.S. Geological Survey, SOUTHWEST REGION Fish Biologist mailing address

6000 J Street Placer Hall

Sacramento CA 95819 US 916-278-3117 bhuntsman@usgs.gov Water resource agencies of the Santa Ana River Watershed, US Fish and Wildlife Service, California Department of Fish and Wildlife Data was transcribed in the field directly into Microsoft Access using Microsoft Access for Microsoft 365 MSO (Version 2402 Build 16.0.17328.20550) 32-bit Metadata was created using Metadata Wizard version 2.0.7 Fitzpatrick, F. A. Waite, I. R. D'Arconte, P. J. Meador, M. R. Maupin, M. A. Gurtz., M. E. 1998 publication https://pubs.usgs.gov US Geological Survey https://doi.org/10.3133/wri984052 Barbour, M. T. Gerritsen, J. Snyder, B. D. Stribling, J. B. US Environmental Protection Agency 1999 2nd publication EPA 841-B-99- 002 Washington, D.C. U.S. Environmental Protection Agency Washington, DC: US Environmental Protection Agency. https://www3.epa.gov/region1/npdes/merrimackstation/pdfs/ar/AR-1164.pdf Bonar, S.A. Hubert, W.A. Willis, D.W. 2009 publication Bethesda, MD American Fisheries Society American Fisheries Society, Bethesda, Maryland. https://pubs.usgs.gov/publication/70046706 Murphy, B.R. (editor) Willis, D.W. (editor) 1996 2nd publication American Fisheries Society Bethesda, MD Moyle, P. B 2002 publication California, USA University of California Press Brock M. Huntsman Larry R Brown Kai Palenscar Chris Jones Kerwin Russell Heather Dyer Brett Mills Marissa Wulff Jason May 2022 publication https://cdnsciencepub.com Canadian Science Publishing https://doi.org/10.1139/cjfas-2021-0210 Marissa L. Wulff 2025 publication https://www.sciencebase.gov U.S. Geological Survey This is a U.S. Geological Survey data release collection, https://doi.org/10.5066/P9W7SV9M. [Updated periodically.] Note to users: Because of continuing updates to this dataset, an access date should be included with the citation https://doi.org/10.5066/P9W7SV9M No formal attribute accuracy tests were conducted Data was checked for values falling within the expected ranges. Data was checked for data duplication and omission. Data set is considered complete for the information presented, as described in the abstract. Users are advised to read the rest of the metadata record carefully for additional details. No formal positional accuracy tests were conducted No formal positional accuracy tests were conducted A full population survey for native fishes of the Santa Ana River was conducted in order to continue documenting the baseline condition of the Santa Ana Sucker and Arroyo Chub within the mainstem. The survey was done in August-September 2025, with sampling beginning at the Rialto Channel and continuing downstream to Van Buren Blvd. The survey used the sampling methods developed in 2015 and 2016 which have been refined and updated based on river conditions over the past five years (Huntsman et al., 2022). Results of the survey will be used to estimate the total population of Santa Ana Sucker and Arroyo Chub within the study area along with estimates of non-native predator fish (channel catfish, largemouth bass, yellow bullhead). The Santa Ana River basin is the largest coastal basin in southern California, draining an area of approximately 6,900 square kilometers (km2). The drainage is greater than 70 percent (%) urban land use type and is divided between two ecoregions, the Southern California Coastal Plains and the Hills and the Southern California Coastal Mountains. The river is highly braided with the potential to shift or create and disengage braids after large storm events. Surveys for this study occur primarily in September, within the middle Santa Ana River currently designated as critical Santa Ana sucker habitat, from above the Prado Dam to the Rialto channel. A stratified random sampling design was used within designated critical Santa Ana sucker habitat of the Santa Ana River. Four main stem strata and three tributary strata (Hole, Sunnyslope, and Anza) within the critical Santa Ana sucker habitat were determined based on the currently known occupied region of the river ( ~ 16 kilometers (km) of stream). A total of 65 stream reaches, each 50 meters (m) long, were randomly selected, because preliminary sensitivity analyses suggested at least 15% of the river needed to be sampled with at least 7 3-pass removal reaches to get adequate population estimates for the entire sampling area (at least 10% 3-pass and at least 15% of strata sampled). Random sampling reaches were generated using ArcGIS, with latitude, longitude and stratum description. Prior to fish sampling, each 50m sampling reach was delineated using georeferenced coordinates, flagging tape, and a measuring tape. The upper and lower ends of the sampling reach were measured with a measuring tape and flagging was used to identify the start and end. Strata are the following (65 Reaches) 1. Strata 1: Rialto - Braid (1,147 m) a. 6 Reaches b. -117.356864; 34.035191 (Braid) c. -117.356864; 34.035191 (RIX Pool) 2. Strata 2: Braid - Main Street Drain (3,023 m) a. 9 Reaches b. -117.373837; 34.012728 (Main Street Drain) 3. Strata 3: Main Street Drain - Arroyo Tequesquite Confluence (5,805 m) a. 20 Reaches b. -117.405194; 33.980061 (Tequesquite Confluence) 4. Strata 4: Arroyo Tequesquite Confluence - Van Buren BLVD (6,246 m) a. 22 Reaches 5. Strata 5: Sunnyslope a. 3 Reaches 6. Strata 6: Anza a. 3 Reaches 7. Strata 7: Hole Creek a. 3 Reaches Field notes were entered into a Microsoft Excel database (Microsoft Excel for Microsoft 365 MSO (16.0.13127.21622) 32-bit, Version 2008) and checked for transcription errors. All coordinates were plotted on google earth to check for accuracy. 20250918 Habitat Field Methods: Reach habitat data were collected for channel width, water depth, mean water column velocity, dominant substrate, cover, distance to cover, and canopy at each reach where fish abundance data were collected generally following National Water-Quality Assessment (NAWQA) Methods for Characterizing Stream Habitat (Fitzpatrick et al., 1998). Reach habitat data were collected on transects positioned perpendicular to the flow with the most downstream transect at the bottom of the study reach and then transects placed every 10 m in the upstream direction to include the entire 50-m reach of stream surveyed for fishes. Channel width at each transect was measured with a measuring tape to the nearest 0.1 m. Depth, mean water column velocity, dominant substrate, cover, and distance to cover were measured at each of 10 evenly spaced points (0.1 of stream width) along each transect. To capture edge microhabitat, measurements either started at left edge of water or ended at right edge of water. Starting point was alternated between transects always starting with the bottom transect at left edge of water. 0 is always left bank (when facing downstream) and 10 is always right bank (when facing downstream). Depth was measured with a graduated wading rod. Velocity was measured with an electronic flow meter and was always collected in the upstream direction. Dominant substrate was determined by visual observation. The nearest object cover was categorized and distance to cover estimated. Percent vegetative canopy cover was measured with a densiometer at left edge of water, right edge of water and upstream and downstream at the midpoint of the transect following methods outlined in Fitzpatrick et al., 1998. Water quality samples were collected using a YSI EXO2 multiparameter sonde. 20250918 Fish Field Methods: We used a stratified random design to sample fishes within designated critical Santa Ana sucker habitat. Each reach was sampled for fish by backpack electrofishing. These methods are widely used in studies of stream fish (Murphy and Willis, 1996; Bonar and others, 2009). Although previous sampling years included mixed methods to capture fishes during native fish surveys, our sampling employed only backpack electrofishing approaches (Wulff, M.L. accessed March 3, 2025). Within each sampling reach, backpack electrofishing surveys using tandem electrofishing units (2 or 3 people) progressed from the downstream end to upstream end of the sampling reach. In addition to individuals using electrofishing units, a netter was assigned to each electrofisher and two people deployed a seine just downstream of the electrofishing units. During electrofishing, units pushed fish downstream into the seine if not captured by the associated netter. A total of three removal passes per sampling reach were conducted for a subset of reaches (6 Reaches). Block nets were only used for the removal sampling reaches, as 3-pass removal sampling with block nets is not possible with currently available resources Shocked fish were captured using 6 millimeter (mm) mesh seine and dip nets and immediately placed in buckets of native stream water. Fish were moved to live wells as soon as possible. The fish from each pass of electrofishing were counted, measured (fork length (FL), total length (TL), weight in grams (g)), and then returned to the stream. Within each segment, a minimum subsample of 30 fish of each fish species captured were weighed. Sampling was conducted in cooperation with the U.S. Fish and Wildlife Service and Riverside-Corona Resource Conservation District personnel who are permitted to take protected species, including electrofishing. All conditions of those permits pertaining to fish handling were followed. Electrofisher settings were 300 volts, 30 Hertz, and 25% duty cycle. Experience of the permit holders indicated these settings captured suckers with minimal or no mortality. 20250918 1.0 1.0 Decimal degrees North American Datum of 1983 (NAD 83) Geodetic Reference System 1980 6378137.000000 298.257222 SAR 2025 Catch Table.csv This Comma Separated Value (CSV) file contains the length, weight, species, and number of fish collected during the survey by backpack electrofishing. Producer Defined Site Site name Producer Defined Site name list in numeric order. Site 1.1 Site 1.2 Site 1.3 Site 1.4 Site 1.5 Site 1.6 Site 2.1 Site 2.2 Site 2.3 Site 2.4 Site 2.5 Site 2.6 Site 2.7 Site 2.8 Site 2.9 Site 3.1 Site 3.2 Site 3.3 Site 3.4 Site 3.5 Site 3.6 Site 3.7 Site 3.8 Site 3.9 Site 3.10 Site 3.11 Site 3.12 Site 3.13 Site 3.14 Site 4.1 Site 4.2 Site 4.3 Site 4.4 Site 4.5 Site 4.6 Site 4.7 Site 4.8 Site 4.9 Site 4.10 Site 4.11 Site 4.12 Site 4.13 Site 4.14 Site 4.15 Site 4.16 Sample Date Fish sample collection date, in date format yyyy-mm-dd. Producer Defined 2025-09-02 2025-09-18 Start Time Sample start time in military time (hh:mm). Producer Defined 9:12 14:32 Pass Pass number assigned to the sampling pass conducted on each reach. Producer Defined 1 5 No Catch Was there a successful catch during sampling? True or False. Producer Defined False No Producer defined True Yes Producer defined Species Species common name Producer Defined ARC -- Arroyo Chub Species common name Producer defined MQF -- Western Mosquitofish Species common name Producer defined YEB -- Yellow Bullhead Species common name Producer defined CCF -- Channel Catfish Species common name Producer defined FHM -- Fathead Minnow Species common name Producer defined SAS -- Santa Ana Sucker Species common name Producer defined GSF -- Green Sunfish Species common name Producer defined LMB -- Largemouth Bass Species common name Producer defined CF -- African Clawed Frog Species common name Producer defined BF -- American Bullfrog Species common name Producer defined No Catch No catch Producer defined RSC -- Red Swamp Crayfish Species common name Producer defined Softshell Turtle Species common name Producer defined Stomach Contents Was stomach content sample data collected? True or false. Producer Defined False No Producer defined True Yes Producer defined Isotope Were tissues collected for isotope analysis? True or false. Producer Defined False No Producer defined True Yes Producer defined FL (mm) Fish fork length in millimeters (mm). Fork length is measured from the tip of the snout to the end of the middle caudal fin rays. Producer Defined NA Not applicable Producer defined 7 505 millimeters TL (mm) Fish total length in millimeters (mm). Total Length is measured from the tip of the snout to the tip of the tail with the tail compressed (pinched together). Producer Defined NA Not applicable Producer defined 10 543 millimeters Weight (g) Weight in grams (g) of the fish or animal specimen captured. Producer Defined NA Not applicable Producer defined 0.04 152.87 grams Count Count of fish captured/sampled . Producer Defined 1 105 Unmeasured Was the fish not measured? True or false. Producer Defined False No Producer defined True Yes Producer defined Mortality Was there mortality among fish (or other organisms) specimens captured during sampling? True or False. Producer Defined False No Producer defined True Yes Producer defined Retained Was the fish retained? True or false? Producer Defined False No Producer defined Fish Number Fish number assigned to an individual fish. Producer Defined 1 201 Study Element Name of study element. (location) Producer Defined SA -- Santa Ana Santa Ana study element (location) Producer defined Sampling Gear Sampling gear type. Producer Defined Backpack Electrofish Backpack Electrofish Producer defined Comment Comment. Producer Defined NA Not applicable Producer defined Comment. SAR 2025 Habitat Table.csv This Comma Separated Value (CSV) file contains environmental habitat measurements collected during the survey, including depth, velocity, substrate, and canopy cover. Producer Defined Site Site name list in numeric order. Producer Defined Site name list in numeric order. Site 1.1 Site 1.2 Site 1.3 Site 1.4 Site 1.5 Site 1.6 Site 2.1 Site 2.2 Site 2.3 Site 2.4 Site 2.5 Site 2.6 Site 2.7 Site 2.8 Site 2.9 Site 3.1 Site 3.2 Site 3.3 Site 3.4 Site 3.5 Site 3.6 Site 3.7 Site 3.8 Site 3.9 Site 3.10 Site 3.11 Site 3.12 Site 3.13 Site 3.14 Site 4.1 Site 4.2 Site 4.3 Site 4.4 Site 4.5 Site 4.6 Site 4.7 Site 4.8 Site 4.9 Site 4.10 Site 4.11 Site 4.12 Site 4.13 Site 4.14 Site 4.15 Site 4.16 Sample Date Habitat sample collection date, in date format yyyy-mm-dd. Producer Defined 2025-09-03 2025-09-18 Start Time Sample start time in military time (hh:mm). Producer Defined 7:06 17:23 Channel Width (m) Wetted channel width in meters (m) Producer Defined 1.1 23.7 meter Transect Transect number Producer Defined 1 6 Interval (m) The interval, in meters (m), for every measurement to be taken across the transect Producer Defined 0.11 2.37 meters Point Sample point at each of 10 evenly spaced points (0.1 of stream width) along each transect where 0 represents the first sample point and 10 represents the last sample. Producer Defined 0 10 Tape Reading Distance along a transect, in meters, moving from the left bank to the right bank Producer Defined 0.0 22 meters Total Depth (cm) Channel depth in centimeters (cm). Producer Defined 0 106 centimeters Velocity1 (m/s) Water velocity in meters per second (m/s) at 0.6 of total depth, measured from the bottom up, at the sampling location on the transect. Mean water column velocity is taken at 0.6 of total depth when water is < 74 cm deep. When water depth is >74 cm, mean water column velocity is taken at 0.2 and 0.8 of total depth and the two measurements are averaged. Negative velocity indicates direction of flow. Negative velocity measurements indicate the presence of a back eddy, or that the reading was taken behind a structure such as a boulder. Producer Defined NA Not applicable Producer defined -0.05 1.85 meters per second (m/s) Velocity2 (m/s) Water velocity in meters per second (m/s) at 0.6 of total depth. When water depth is >74 cm, mean water column velocity is taken at 0.2 and 0.8 of total depth and the two measurements are averaged. Producer Defined NA Not applicable Producer defined 0.02 0.54 meters per second (m/s) Velocity3 (m/s) Water velocity in meters per second (m/s) at 0.8 of total depth. When water depth is >74 cm, mean water column velocity is taken at 0.2 and 0.8 of total depth and the two measurements are averaged. Negative velocity indicates direction of flow. Negative velocity measurements indicate the presence of a back eddy, or that the reading was taken behind a structure such as a boulder. Producer Defined NA Not applicable Producer defined 0.01 0.46 meters per second (m/s) Dominant Substrate Dominant substrate, measured in centimeters (cm) Producer Defined Cobble (65-256) Rocky substrate consisting of cobble or rocks 65-256 cm in diameter. Producer defined Sand (<2) Sandy substrate consisting of sand grains <2 cm in diameter. Producer defined Boulder (>256) Rocky substrate consisting of rocks >256 cm in diameter. Producer defined Gravel (2-64) Gravel substrate consisting of small rocks 2-64 cm in diameter. Producer defined Mud/Silt Mud or silt Producer defined Bedrock Solid rock layer Producer defined Cover Type Habitat cover consists of any mineral or organic matter that produces shelter for aquatic organisms (mainly fish) to rest, hide, or feed and includes natural features of a stream, such as large boulders, woody debris, undercut banks, and aquatic macrophyte beds, as well as artificial structures, such as discarded tires, appliances, and parts of automobiles. For fish cover, these features need to be at least 0.3 m long, 0.3 m wide, 0.3 m high, and in or just above (<0.1 m) water that is at least 0.3 m deep. Producer Defined NA Not applicable Producer defined Overhanging Vegetation Overhanging Vegetation Producer defined Boulder Boulder Producer defined LWD Large Woody Debris Producer defined EV Emergent Vegetation Producer defined Undercut Bank Undercut Bank Producer defined Roots Roots of trees or plants. Producer defined Other Object Other Object Producer defined Distance to Cover (m) Distance to cover from sampling Point, in meters (m), to nearest fish suitable cover. For fish cover, these features need to be at least 0.3 m long, 0.3 m wide, 0.3 m high, and in or just above (<0.1 m) water that is at least 0.3 m deep. Producer Defined NA Not applicable Producer defined 0.0 2.0 meters Canopy Left Densiometer reading for left bank. A densiometer is an instrument used for taking measurements of percent canopy cover. Producer Defined NA Not applicable Producer defined 0 17 Canopy Upstream Densiometer reading for looking upstream. A densiometer is an instrument used for taking measurements of percent canopy cover Producer Defined NA Not applicable Producer defined 0 17 Canopy Downstream Densiometer reading looking downstream. A densiometer is an instrument used for taking measurements of percent canopy cover Producer Defined NA Not applicable Producer defined 0 17 Canopy Right Densiometer reading for right bank. A densiometer is an instrument used for taking measurements of percent canopy cover Producer Defined NA Not applicable Producer defined 0 17 Comment Notes/observations documented in the field during sampling or during subsequent data quality review. Producer Defined NA Not Applicable/No comments Producer defined Notes/observations documented in the field during sampling or during subsequent data quality review. SAR 2025 Sample Table.csv This Comma Separated Value (CSV) file contains details of the backpack electrofishing survey including seconds of shocking time for each backpack electrofishing unit, start and end times, geographical location information, and discrete water quality parameters. Producer Defined Site Site name list in numeric order. Producer Defined Site name list in numeric order. Site 1.1 Site 1.2 Site 1.3 Site 1.4 Site 1.5 Site 1.6 Site 2.1 Site 2.2 Site 2.3 Site 2.4 Site 2.5 Site 2.6 Site 2.7 Site 2.8 Site 2.9 Site 3.1 Site 3.2 Site 3.3 Site 3.4 Site 3.5 Site 3.6 Site 3.7 Site 3.8 Site 3.9 Site 3.10 Site 3.11 Site 3.12 Site 3.13 Site 3.14 Site 4.1 Site 4.2 Site 4.3 Site 4.4 Site 4.5 Site 4.6 Site 4.7 Site 4.8 Site 4.9 Site 4.10 Site 4.11 Site 4.12 Site 4.13 Site 4.14 Site 4.15 Site 4.16 Sample Date Sample collection date, in date format yyyy-mm-dd. Producer Defined 2025-09-02 2025-09-18 Blocknet used? Was a blocknet used during this sample period? TRUE (yes) or FALSE (no). Producer Defined False no Producer defined True yes Producer defined Efish1 (sec) Pass 1 Electrofishing unit 1 effort, in seconds for pass 1 Producer Defined 241 1046 seconds Efish2 (sec) Pass 1 Electrofishing unit 2 effort, in seconds for pass 1 Producer Defined 222 1068 seconds Efish3 (sec) Pass 1 Electrofishing unit 3 effort, in seconds for pass 1 Producer Defined NA Not applicable Producer defined 350 700 seconds Efish4 (sec) Pass 1 Electrofishing unit 4 effort, in seconds for pass 1 Producer Defined NA Not applicable Producer defined 383 613 seconds Efish1 (sec) Pass 2 Electrofishing unit 1 effort, in seconds for pass 2 Producer Defined 260 711 seconds Efish2 (sec) Pass 2 Electrofishing unit 1 effort, in seconds for pass 2 Producer Defined 273 728 seconds Efish3 (sec) Pass 2 Electrofishing unit 3 effort, in seconds for pass 2 Producer Defined NA Not applicable Producer defined 269 703 seconds Efish4 (sec) Pass 2 Electrofishing unit 4 effort, in seconds for pass 2 Producer Defined NA Not applicable Producer defined 330 380 seconds Efish1 (sec) Pass 3 Electrofishing unit 1 effort, in seconds for pass 3 Producer Defined NA Not applicable Producer defined 223 720 seconds Efish 2 (sec) Pass 3 Electrofishing unit 2 effort, in seconds for pass 3 Producer Defined NA Not applicable Producer defined 208 752 seconds Efish3 (sec) Pass 3 Electrofishing unit 3 effort, in seconds for pass 3 Producer Defined NA Not applicable Producer defined 186 664 seconds Efish4 (sec) Pass 3 Electrofishing unit 4 effort, in seconds for pass 3 Producer Defined NA Not applicable Producer defined 259 329 seconds Efish1 (sec) Pass 4 Electrofishing unit 1 effort, in seconds for pass 4 Producer Defined NA Not applicable Producer defined 247 459 seconds Efish2 (sec) Pass 4 Electrofishing unit 2 effort, in seconds for pass 4 Producer Defined NA Not applicable Producer defined 90 419 seconds Efish3 (sec) Pass 4 Electrofishing unit 3 effort, in seconds for pass 4 Producer Defined NA Not applicable Producer defined 189 366 seconds Efish1 (sec) Pass 5 Electrofishing unit 1 effort, in seconds for pass 5 Producer Defined NA Not applicable Producer defined 235 411 seconds Efish2 (sec) Pass 5 Electrofishing unit 2 effort, in seconds for pass 5 Producer Defined NA Not applicable Producer defined 234 436 seconds Efish3 (sec) Pass 5 Electrofishing unit 3 effort, in seconds for pass 5 Producer Defined NA Not applicable Producer defined 229 461 seconds Start Time Pass 1 Sample collection start time in hours and minutes (hh:mm) for pass 1, 24-hour clock Producer Defined 9:11 14:27 in hours and minutes (hh:mm) End Time Pass 1 Sample collection end time in hours and minutes (hh:mm) for pass 1, 24-hour clock Producer Defined NA Not applicable Producer defined 9:28 14:39 in hours and minutes (hh:mm) Start Time Pass 2 Sample collection start time in hours and minutes (hh:mm) for pass 2, 24-hour clock Producer Defined 9:30 14:41 Sample collection start time in hours and minutes (hh:mm) for pass 3, 24-hour clock End Time Pass 2 Sample collection end time in hours and minutes (hh:mm) for pass 2, 24-hour clock Producer Defined 9:43 14:50 Sample collection start time in hours and minutes (hh:mm) for pass 3, 24-hour clock Start Time Pass 3 Sample collection start time in hours and minutes (hh:mm) for pass 3, 24-hour clock Producer Defined NA Not applicable Producer defined 9:47 14:52 in hours and minutes (hh:mm) End Time Pass 3 Sample collection end time in hours and minutes (hh:mm) for pass 3, 24-hour clock Producer Defined NA Not applicable User defined 9:47 15:03 in hours and minutes (hh:mm) Start Time Pass 4 Sample collection start time in hours and minutes (hh:mm) for pass 4, 24-hour clock Producer Defined NA Not applicable Producer defined 10:48 14:15 in hours and minutes (hh:mm) End Time Pass 4 Sample collection end time in hours and minutes (hh:mm) for pass 4, 24-hour clock Producer Defined NA Not applicable Producer defined 11:01 14:23 in hours and minutes (hh:mm) Start Time Pass 5 Sample collection start time in hours and minutes (hh:mm) for pass 5, 24-hour clock Producer Defined NA Not applicable Producer defined 11:31 14:20 in hours and minutes (hh:mm) End Time Pass 5 Sample collection end time in hours and minutes (hh:mm) for pass 5, 24-hour clock Producer Defined NA Not applicable Producer defined 11:39 14:33 in hours and minutes (hh:mm) Latitude Start Decimal degrees (DD) latitude of pass start. North American Datum of 1983 (NAD 83) Producer Defined 33.96443 34.04682 Decimal degrees (DD) Longitude Start Decimal degrees (DD) longitude of pass start. North American Datum of 1983 (NAD 83) Producer Defined -117.46056 -117.3541 Decimal degrees (DD) Latitude End Decimal degrees (DD) latitude of pass end. North American Datum of 1983 (NAD 83) Producer Defined 33.96453 34.04726 Decimal degrees (DD) Longitude End Decimal degrees (DD) longitude of pass end. North American Datum of 1983 (NAD 83) Producer Defined -117.46002 -117.35244 Decimal degrees (DD) Temperature Water temperature in degrees Celsius. Producer Defined 20.3 31.2 degrees Celsius Specific conductance Specific conductance reported in microsiemens per centimeter at 25 degrees Celsius. Producer Defined 785 1048 Salinity Salinity in Practical Salinity Unit (PSU). Producer Defined 0.38 0.52 Turbidity Turbidity collected in Formazin Nephelometric Units (FNU) Producer Defined NA Not applicable Producer defined 0.08 10.34 DO concentration Dissolved oxygen in milligrams per liter (mg/L) Producer Defined 6.68 8.41 DO saturation Dissolved oxygen, percent saturation (%) Producer Defined 83.9 101.3 pH Potential of Hydrogen (pH) as an indicator of acidity or alkalinity Producer Defined 7.09 8.14 Comment Notes/observations documented in the field during sampling or during subsequent data quality review. Producer Defined NA Not Applicable/No Comment Producer defined Notes/observations documented in the field during sampling or during subsequent data quality review. This U.S. Geological Survey ScienceBase Data Release contains the following three CSV files detailing fish population and habitat data collected in 2025 to support development of the upper Santa Ana River Habitat Conservation Plan for the Santa Ana Sucker (Catostomus santaanae) and the Arroyo Chub (Gila orcuttii) in the Santa Ana River, California. SAR 2025 Catch Table.csv: This Comma Separated Value (CSV) file contains the length, weight, species, and number of fish collected during the survey by backpack electrofishing. SAR 2025 Habitat Table.csv: This Comma Separated Value (CSV) file contains environmental habitat measurements collected during the survey, including depth, velocity, substrate, and canopy cover. SAR 2025 Sample Table.csv: This Comma Separated Value (CSV) file contains details of the backpack electrofishing survey including seconds of shocking time for each backpack electrofishing unit, start and end times, geographical location information, and discrete water quality parameters. Wulff, M.L., Huntsman, B.M., Gronemyer, J.L., and Buxton, J.M., 2026, Santa Ana River Native Fish Population and Habitat Data, Santa Ana River, California, 2025: U.S. Geological Survey data release, https://doi.org/10.5066/P1Z7RCRC U.S. Geological Survey GS ScienceBase mailing address

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Denver CO 80225 United States 1-888-275-8747 sciencebase@usgs.gov Unless otherwise stated, all data, metadata and related materials are considered to satisfy the quality standards relative to the purpose for which the data were collected. Although these data and associated metadata have been reviewed for accuracy and completeness and approved for release by the U.S. Geological Survey (USGS), no warranty expressed or implied is made regarding the display or utility of the data on any other system or for general or scientific purposes, nor shall the act of distribution constitute any such warranty. Digital Data https://doi.org/10.5066/P1Z7RCRC None 20260107 Marissa L Wulff PACIFIC REGION mailing and physical

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