Feature Name | Class | Elev. meters | County | Latitude DMS | Longitude DMS |
| Iron Spring | Spring | 884 | San Diego | 32 39 51 N | 116 13 10 W |
| Iron Spring | Spring | 1228 | San Diego | 32 59 47 N | 116 37 54 W |
| Iron Spring | Spring | 391 | San Luis Obispo | 35 27 55 N | 120 31 24 W |
| Iron Spring | Spring | 842 | San Luis Obispo | 35 11 16 N | 120 05 37 W |
| Iron Spring | Spring | 1654 | Tehama | 40 08 53 N | 122 50 47 W |
| Iron Spring | Spring | 2635 | Tulare | 36 16 24 N | 118 12 22 W |
| Iron Spring Canyon | Valley | | San Diego | 33 25 20 N | 116 41 14 W |
| Iron Spring Gulch | Valley | | Tehama | 40 08 04 N | 122 51 09 W |
| Iron Spring Mountain | Summit | 1748 | Riverside | 33 27 12 N | 116 41 50 W |
| Iron Spring Ranch | Locale | 315 | Kings | 35 51 05 N | 120 09 26 W |
| Iron Spring Ridge | Ridge | 1515 | Tehama | 40 08 36 N | 122 51 32 W |
| Iron Spring Ridge | Ridge | 1543 | Tehama | 40 08 40 N | 122 51 24 W |
| Iron Springs | Spring | 409 | Monterey | 36 02 40 N | 120 45 48 W |
| Iron Springs Canyon | Valley | | San Diego | 33 03 02 N | 116 41 45 W |
| Iron Springs Creek | Stream | | San Diego | 33 20 09 N | 116 51 45 W |
| Iron Target Shooting Area | Locale | 1460 | Los Angeles | 34 21 10 N | 118 13 08 W |
| Iron Trough Canyon | Valley | | Ventura | 34 19 53 N | 118 43 22 W |
| Iron Trough Spring | Spring | 865 | Siskiyou | 41 49 40 N | 122 34 36 W |
| Iron Wedge Prospect | Mine | 1755 | Inyo | 36 57 47 N | 118 09 27 W |
| Ironside Mountain | Summit | 1602 | Trinity | 40 49 56 N | 123 27 02 W |
| Ironside Spring | Spring | 1415 | San Diego | 33 08 01 N | 116 35 48 W |
| Ironsides | Populated Place | 20 | Los Angeles | 33 48 40 N | 118 18 22 W |
| Ironsides Mine | Mine | 1546 | Sierra | 39 30 15 N | 120 45 37 W |
| Ironsides Museum | Building | 229 | Trinity | 40 52 05 N | 123 31 12 W |
| Ironton Flats | Flat | 633 | Madera | 37 09 34 N | 119 35 57 W |
| Ironwood Campsite | Locale | 2030 | San Bernardino | 34 18 14 N | 117 00 43 W |
| Ironwood Country Club | Locale | 151 | Riverside | 33 41 15 N | 116 22 41 W |
| Ironwood Wash | Valley | | San Bernardino | 34 19 29 N | 115 13 37 W |
| Irrigation Reservoir 2011-002 Dam | Dam | 115 | Kern | 35 19 60 N | 118 58 03 W |
| Irrigosa | Populated Place | 85 | Madera | 36 53 28 N | 119 59 15 W |
| Irvine | Populated Place | 17 | Orange | 33 40 10 N | 117 49 23 W |
| Irvine Bowl Park | Park | 24 | Orange | 33 32 54 N | 117 47 00 W |
| Irvine Coast Country Club | Locale | 4 | Orange | 33 36 07 N | 117 52 53 W |
| Irvine Coast Marine Life Refuge | Park | -2 | Orange | 33 34 00 N | 117 50 07 W |
| Irvine Lake | Reservoir | 240 | Orange | 33 47 06 N | 117 43 27 W |
| Irvine Lake Park | Park | 268 | Orange | 33 46 06 N | 117 43 08 W |
| Irvine Mesa | Summit | 409 | Orange | 33 44 30 N | 117 39 07 W |
| Irvine Park | Park | 178 | Orange | 33 47 43 N | 117 44 54 W |
| Irvine Ranch | Locale | 38 | Orange | 33 43 47 N | 117 47 00 W |
| Irvine Rest Area | Park | 399 | Mendocino | 39 35 15 N | 123 26 52 W |
| Irvine School | School | 66 | Orange | 33 40 42 N | 117 45 23 W |
| Irvine Siding | Locale | 21 | Orange | 33 42 58 N | 117 49 05 W |
| Irvine Terrace Park | Park | -3 | Orange | 33 35 45 N | 117 52 50 W |
| Irvine Valley College | School | 40 | Orange | 33 40 37 N | 117 46 38 W |
| Irvine Village Shopping Center | Locale | 38 | Orange | 33 40 50 N | 117 46 43 W |
| Irving (historical) | Populated Place | 42 | Marin | 38 01 01 N | 122 43 28 W |
| Irving Creek | Stream | | Marin | 38 01 00 N | 122 43 26 W |
| Irving Creek | Stream | | Siskiyou | 41 28 04 N | 123 30 02 W |
| Irving Creek Ranch | Locale | 465 | Siskiyou | 41 28 02 N | 123 28 14 W |
| Irving Creek School (historical) | School | 228 | Siskiyou | 41 28 10 N | 123 29 44 W |
| Irving Finch River Access | Park | 37 | Glenn | 39 45 02 N | 121 59 50 W |
| Irving Group Picnic Area | Locale | 43 | Marin | 38 01 00 N | 122 43 23 W |
| Irving High School | School | 32 | Orange | 33 42 08 N | 117 46 56 W |
| Irving L Branch Elementary School | School | 728 | Kern | 34 55 43 N | 117 56 43 W |
| Irving M Scott School | School | 12 | San Francisco | 37 45 31 N | 122 23 23 W |
| Irving Martin Library | Building | 4 | San Joaquin | 37 58 46 N | 121 18 35 W |
| Irving Middle School | School | 123 | Los Angeles | 34 06 59 N | 118 14 27 W |
| Irving Mountain | Summit | 1621 | Siskiyou | 41 29 09 N | 123 26 14 W |
| Irving Park | Park | -18 | Imperial | 32 51 15 N | 115 34 30 W |
| Irving Schachter Park | Park | 49 | Los Angeles | 34 02 25 N | 118 23 56 W |
| Irving School (historical) | School | 1303 | Inyo | 37 21 42 N | 118 25 57 W |
| Irvings Crest | Populated Place | 414 | San Diego | 32 58 47 N | 116 54 44 W |
| Irvington Baptist Church | Church | | Alameda | 37 31 43 N | 121 57 29 W |
| Irvington Branch Alameda County Library | Building | 12 | Alameda | 37 31 22 N | 121 57 60 W |
| Irvington Community Park | Park | 12 | Alameda | 37 31 21 N | 121 57 54 W |
| Irvington District | Populated Place | 11 | Alameda | 37 31 22 N | 121 58 18 W |
| Irvington High School | School | 13 | Alameda | 37 31 26 N | 121 57 59 W |
| Irvington Presbyterian Church | Church | | Alameda | 37 31 54 N | 121 57 46 W |
| Irvington Pumping Station | Locale | 19 | Alameda | 37 32 32 N | 121 57 18 W |
| Irvington School | School | 18 | Alameda | 37 32 04 N | 121 57 47 W |
| Irvington Station Fremont Post Office | Post Office | 16 | Alameda | 37 31 56 N | 121 57 42 W |
| Irwin | Populated Place | 30 | Merced | 37 23 49 N | 120 51 00 W |
| Irwin Bright Lake | Lake | 2160 | Tuolumne | 37 59 20 N | 119 33 36 W |
| Irwin Elementary School | School | 856 | San Bernardino | 34 31 20 N | 117 17 50 W |
| Irwin Estates | Populated Place | 667 | San Bernardino | 34 55 17 N | 117 01 41 W |
| Irwin-Hilmer Branch Merced County Library | Building | 29 | Merced | 37 24 15 N | 120 51 04 W |
| Irwindale | Populated Place | 143 | Los Angeles | 34 06 25 N | 117 56 07 W |
| Irwindale City Hall | Building | 142 | Los Angeles | 34 06 17 N | 117 56 00 W |
| Irwindale Park | Park | 142 | Los Angeles | 34 06 17 N | 117 56 01 W |
| Irwindale Post Office | Post Office | 142 | Los Angeles | 34 06 21 N | 117 56 02 W |
| Irwindale Public Library | Building | 141 | Los Angeles | 34 06 15 N | 117 55 58 W |
| Irwindale Raceway | Locale | 167 | Los Angeles | 34 07 33 N | 117 56 18 W |
| Irwindale Siding | Locale | 132 | Los Angeles | 34 05 53 N | 117 56 29 W |
| Irwindale Square Shopping Center | Locale | 128 | Los Angeles | 34 05 19 N | 117 56 06 W |
| Isaac Fesler Elementary School | School | 72 | Santa Barbara | 34 57 22 N | 120 25 12 W |
| Isaac L Sowers Middle School | School | 3 | Orange | 33 39 52 N | 117 57 54 W |
| Isaac Miller Elementary School | School | 69 | Santa Barbara | 34 56 28 N | 120 25 52 W |
| Isaac Newton Graham Middle School | School | 36 | Santa Clara | 37 22 54 N | 122 05 07 W |
| Isaacs Ditch | Canal | 155 | Amador | 38 17 41 N | 120 52 59 W |
| Isabel Cook Recreation Center | Park | 24 | Marin | 37 58 56 N | 122 34 05 W |
| Isabel Creek | Stream | | Santa Clara | 37 22 60 N | 121 41 33 W |
| Isabel Henderson Branch Torrance Public Library | Building | 32 | Los Angeles | 33 50 30 N | 118 21 55 W |
| Isabel Placer Mine | Mine | 1680 | Sierra | 39 31 10 N | 120 48 16 W |
| Isabel Valley | Valley | | Santa Clara | 37 19 23 N | 121 33 23 W |
| Isabella (historical) | Populated Place | 767 | Kern | 35 39 20 N | 118 27 40 W |
| Isabella Auxiliary Dam | Dam | 801 | Kern | 35 38 33 N | 118 28 10 W |
| Isabella Lake | Reservoir | 791 | Kern | 35 38 47 N | 118 28 56 W |
| Isabella Main Dam | Dam | 797 | Kern | 35 38 46 N | 118 28 56 W |
| Isabella Marina Number Two | Locale | 788 | Kern | 35 39 06 N | 118 29 03 W |
| Isabella Point Boat Ramp | Locale | 787 | Kern | 35 38 55 N | 118 28 19 W |
| Isabella Tunnel | Mine | 1926 | Alpine | 38 37 00 N | 119 45 25 W |
| Isabelle Jackson Elementary School | School | 11 | Sacramento | 38 27 45 N | 121 23 31 W |
| Isabelle Spring | Spring | 1069 | San Bernardino | 34 32 02 N | 117 05 34 W |
| Isador Cohen Elementary School | School | 15 | Sacramento | 38 33 40 N | 121 22 08 W |
| Isaiah (historical) | Populated Place | 300 | Butte | 39 43 04 N | 121 26 32 W |
| Isbel Grove | Woods | 25 | Santa Cruz | 36 59 31 N | 122 00 43 W |
| Isbel Grove Camp (historical) | Locale | 22 | Santa Cruz | 36 59 30 N | 122 00 44 W |
| Isbell Middle School | School | 76 | Ventura | 34 20 57 N | 119 03 59 W |
| Isberg Lakes | Lake | 3010 | Madera | 37 38 57 N | 119 18 50 W |
| Isberg Pass | Gap | 3209 | Madera | 37 38 38 N | 119 19 35 W |