| 1 | Quality Well Drillers Inc. | 478 | 3,303 | 3,524 |
| 2 | Calwater Drilling Company Inc. | 339 | 1,828 | 5,421 |
| 3 | Living Water Well Drilling | 332 | 343 | 441 |
| 4 | Masellis Drilling Inc. | 112 | 618 | 6,081 |
| 5 | Dos Palos Well Drilling | 80 | 598 | 788 |
| 6 | Myers Brothers Well Drilling Inc. | 58 | 483 | 2,865 |
| 7 | Allison Sierra | 39 | 58 | 127 |
| 8 | Atwater Well Drilling | 34 | 35 | 40 |
| 9 | Prieto Anthony J Water Well Drilling Inc. | 31 | 31 | 637 |
| 10 | Cen Cal Drilling Inc. | 27 | 30 | 31 |
| 11 | Cascade Drilling L P | 23 | 54 | 2,827 |
| 12 | Henry George Farnsworth | 22 | 43 | 43 |
| 13 | Canepa And Sons Inc. | 20 | 36 | 3,173 |
| 14 | US Drilling | 16 | 26 | 29 |
| 15 | Maggiora Bros Drilling Inc. | 15 | 51 | 4,674 |
| 16 | Castle Well Drilling Inc. | 12 | 12 | 294 |
| 17 | Bradley & Sons Inc. | 11 | 24 | 3,627 |
| 18 | Arthur & Orum Well Drilling Inc. | 9 | 173 | 3,219 |
| 19 | Anthony J Prieto | 9 | 30 | 2,330 |
| 20 | Corrpro Companies Inc. | 9 | 9 | 737 |
| 21 | Gregg Drilling & Testing Inc. | 8 | 36 | 4,828 |
| 22 | Nor - Cal Pump & Well Drilling Inc. | 8 | 15 | 248 |
| 23 | M & M Well Drilling | 8 | 13 | 74 |
| 24 | Vics Well Drilling Inc. | 8 | 8 | 337 |
| 25 | Precision Well Drilling Inc. | 8 | 8 | 189 |
| 26 | Well Industries Inc. | 7 | 10 | 558 |
| 27 | Gregg Drilling LLC | 7 | 7 | 558 |
| 28 | Stonehouse Well Drilling | 6 | 10 | 157 |
| 29 | Castle Construction & Well Drilling Inc. | 6 | 9 | 142 |
| 30 | Big River Drilling LLC | 6 | 6 | 715 |
| 31 | Strickland Enterprises Inc. | 6 | 6 | 2,026 |
| 32 | American Construction And Supply Inc. | 5 | 23 | 1,685 |
| 33 | Rainbow Drilling | 5 | 7 | 207 |
| 34 | Scott Belknap Well Drilling Inc. | 5 | 6 | 1,131 |
| 35 | H & B Drilling And Sons LLC | 5 | 5 | 414 |
| 36 | Hennings Bros Drilling Co. Inc. | 4 | 1,056 | 6,823 |
| 37 | Yosemite Falls Inc. | 4 | 9 | 706 |
| 38 | J R Gross Wells & Pumps | 3 | 27 | 27 |
| 39 | Arsenal Well Drilling Inc. | 3 | 3 | 234 |
| 40 | Eaton Drilling Co. LLC | 2 | 24 | 3,793 |
| 41 | All Well Abandonment | 2 | 18 | 607 |
| 42 | Zim Industries Inc. Dba Bakersfield Well & Pump Co. | 2 | 11 | 1,716 |
| 43 | Johnson Drilling Co. | 2 | 9 | 11,865 |
| 44 | Farwest Corrosion Control Company | 2 | 8 | 2,649 |
| 45 | Beymer Well Service | 2 | 6 | 2,921 |
| 46 | Grabow Well Drilling Company | 2 | 5 | 2,646 |
| 47 | Joey's Well Drilling & Construction | 2 | 4 | 46 |
| 48 | Valley Well Drilling LP | 2 | 2 | 410 |
| 49 | Yellow Jacket Drilling Services LLC | 2 | 2 | 291 |
| 50 | C R Well Drilling | 2 | 2 | 455 |
| 51 | Water Resource Heritage Inc. | 2 | 2 | 33 |
| 52 | Roadrunner Drilling & Pump Company Inc. | 2 | 2 | 205 |
| 53 | Petro - Lud Inc. | 2 | 2 | 26 |
| 54 | Roscoe Moss Company | 2 | 2 | 130 |
| 55 | Everett A Loewenstein | 1 | 324 | 357 |
| 56 | Don's Drilling Company | 1 | 27 | 28 |
| 57 | Tanko Bros Inc. | 1 | 3 | 2,617 |
| 58 | 99 Drilling LLC | 1 | 1 | 265 |
| 59 | Gregory Drilling Incorporated | 1 | 1 | 143 |
| 60 | Altamont Water Well And Pump | 1 | 1 | 90 |
| 61 | Hch Water Wells Inc. | 1 | 1 | 43 |
| 62 | Drew & Hefner Well Drilling | 1 | 1 | 43 |
| 63 | Simpson Drilling Company | — | 388 | 644 |
| 64 | Signal Drilling Company | — | 314 | 8,301 |
| 65 | Blake Hennings | — | 260 | 1,362 |
| 66 | Aquarius Drilling And Pump Co. | — | 239 | 288 |
| 67 | Myers Brothers Inc. | — | 200 | 796 |
| 68 | Osterberg And Stewart | — | 200 | 636 |
| 69 | Osterberg And Carroll | — | 193 | 561 |
| 70 | Olson's Plbg & Heating | — | 133 | 308 |
| 71 | Bill Belknap | — | 119 | 2,758 |
| 72 | Thomas F Madsen | — | 117 | 128 |
| 73 | Myers Reverse, Inc. | — | 113 | 2,389 |
| 74 | Anderson Pump Company | — | 111 | 299 |
| 75 | Martin Pump & Supply Inc. | — | 107 | 2,524 |
| 76 | Weimer Stan Enterprises Inc. | — | 99 | 377 |
| 77 | W D C Exploration & Wells | — | 90 | 2,421 |
| 78 | Pearson Well Drilling | — | 82 | 176 |
| 79 | Ritchey Bros | — | 73 | 183 |
| 80 | C E Cates Well Drilling | — | 62 | 108 |
| 81 | Hall Thomas A | — | 55 | 1,789 |
| 82 | D P Well Drilling | — | 39 | 60 |
| 83 | Hoffman J F Well Driller | — | 38 | 41 |
| 84 | Chambers D P Drilling | — | 36 | 488 |
| 85 | Cates Lloyd Drilling | — | 35 | 56 |
| 86 | Bootjack Drilling Inc. | — | 34 | 649 |
| 87 | Joe W Baker | — | 33 | 48 |
| 88 | Gehrke-Bloomer | — | 30 | 160 |
| 89 | Diamond Core Drilling Inc. | — | 26 | 480 |
| 90 | Myers And Summers | — | 23 | 75 |
| 91 | DP Drilling | — | 23 | 30 |
| 92 | Mel Meyer | — | 20 | 101,127 |
| 93 | Arthur's Well Drilling | — | 18 | 41 |
| 94 | Beylik Drilling & Pump Service | — | 17 | 1,267 |
| 95 | Howk Well & Equipment Co. | — | 17 | 48 |
| 96 | Ace Drilling & Pump Co. | — | 17 | 27 |
| 97 | Anderson Brothers Water Well Drilling & Domestic Pumps | — | 15 | 492 |
| 98 | Layne Christensen Company | — | 14 | 2,362 |
| 99 | Faria Welldrilling | — | 13 | 250 |
| 100 | Davis & Davis Well Drilling | — | 11 | 315 |
| 101 | B & W Drilling | — | 10 | 132 |
| 102 | Moore Twining Associates Inc. | — | 10 | 46 |
| 103 | Cascade Drilling Inc. - California | — | 9 | 3,167 |
| 104 | Bloomer E | — | 9 | 102 |
| 105 | Waterwell Plus | — | 9 | 27 |
| 106 | Guardino Well Drilling Inc. | — | 8 | 1,736 |
| 107 | A A A Drilling Service | — | 8 | 99 |
| 108 | Modesto Well Drillers | — | 8 | 124 |
| 109 | Hydro Resources - West Inc. | — | 8 | 97 |
| 110 | Bsk Associates | — | 8 | 37 |
| 111 | Spectrum Exploration Inc. | — | 7 | 307 |
| 112 | Stroming Machinery | — | 6 | 2,391 |
| 113 | Mariposa Well Drilling Company Inc. | — | 6 | 1,146 |
| 114 | Aquarius Well Drilling Inc. | — | 6 | 121 |
| 115 | National E W P Inc. | — | 5 | 431 |
| 116 | Moosios Pump Co. Inc. | — | 5 | 127 |
| 117 | Datum Exploration Inc. | — | 5 | 223 |
| 118 | Winter Abajian Well Drilling | — | 5 | 203 |
| 119 | Kenneth J Mcavoy | — | 5 | 161 |
| 120 | Westside Drilling & Development Co. | — | 5 | 77 |
| 121 | Bert Belknap | — | 5 | 50 |
| 122 | Van Loon Jack | — | 5 | 49 |
| 123 | Westervelt Well Drilling | — | 4 | 122 |
| 124 | Panero Well Drilling Inc. | — | 4 | 921 |
| 125 | Western Well Drilling Co. Ltd | — | 4 | 842 |
| 126 | Testamerica Drilling Corp | — | 4 | 378 |
| 127 | Cullum Systems Incorporated | — | 4 | 277 |
| 128 | Joe Souza | — | 4 | 72 |
| 129 | Jvl Water Well Drilling | — | 4 | 52 |
| 130 | Abajian Seth Well Drilling | — | 4 | 41 |
| 131 | Valley Pump & Motor Works Inc. | — | 3 | 181 |
| 132 | Levnard T Larson | — | 3 | 681 |
| 133 | Layne-Western Co. Inc. | — | 3 | 255 |
| 134 | Golden Empire Drilling | — | 3 | 168 |
| 135 | Tcb Well Drilling | — | 3 | 32 |
| 136 | Wellco Drilling Inc. | — | 2 | 1,375 |
| 137 | Kvilhaug Drilling & Pump Inc. | — | 2 | 327 |
| 138 | Myers Well Drilling Inc. | — | 2 | 763 |
| 139 | Purviance Drillers Inc. | — | 2 | 663 |
| 140 | Krazan & Associates | — | 2 | 30 |
| 141 | Cache Creek Drilling | — | 2 | 247 |
| 142 | West Hazmat Drilling Corp | — | 2 | 1,702 |
| 143 | Woodward Drilling Company Inc. | — | 2 | 1,542 |
| 144 | H & B Drilling | — | 2 | 1,248 |
| 145 | Rockwell Drilling Co. | — | 2 | 244 |
| 146 | John A Brandt | — | 2 | 143 |
| 147 | Dexter Machinery | — | 2 | 53 |
| 148 | Groundwater Technology | — | 2 | 46 |
| 149 | T C B Well Drilling Co. | — | 2 | 35 |
| 150 | Russ Ervin-Well Drilling | — | 2 | 25 |
| 151 | Consolidated Testing Laboratories Inc. | — | 1 | 1,405 |
| 152 | Tanko Well Drilling | — | 1 | 3,311 |
| 153 | Walt Bannon Drilling Inc. | — | 1 | 2,498 |
| 154 | Bertram Drilling Inc. | — | 1 | 1,171 |
| 155 | D & D Pumps | — | 1 | 46 |
| 156 | Landino Drilling Co. | — | 1 | 151 |
| 157 | Crum Sam Water Well Drilling Inc. | — | 1 | 591 |
| 158 | Fronk's Mountain Drilling | — | 1 | 2,378 |
| 159 | Diversified Exploration Co. Inc. | — | 1 | 751 |
| 160 | Aqua Engineering | — | 1 | 641 |
| 161 | Brown Elvin | — | 1 | 422 |
| 162 | Clovis Pump & Water Well | — | 1 | 323 |
| 163 | Bayland Drillers | — | 1 | 317 |
| 164 | V & W Drilling | — | 1 | 310 |
| 165 | Redfeairn R L Drilling | — | 1 | 195 |
| 166 | Blain & Imbach Well Drilling | — | 1 | 168 |
| 167 | K F Guernsey | — | 1 | 119 |
| 168 | Xxx | — | 1 | 113 |
| 169 | Jeffrey L Gross | — | 1 | 103 |
| 170 | Rasmussen Well & Pump | — | 1 | 88 |
| 171 | Harvey Gehrke | — | 1 | 63 |
| 172 | Floyd's Well Drilling | — | 1 | 58 |
| 173 | Roche Well And Pump Company | — | 1 | 54 |
| 174 | Melton Drilling Co. | — | 1 | 46 |
| 175 | All American Water Supply OF California Inc. | — | 1 | 40 |
| 176 | Andy Noblin | — | 1 | 39 |
| 177 | Dan's Water Well & Pump Service Inc. | — | 1 | 37 |
| 178 | Arthur T Ball | — | 1 | 37 |
| 179 | H A Moore Drlng | — | 1 | 32 |