| BELLINGHAM-WATER DIVISION CITY OF | 139,912 | 18 | Clean |
| FERNDALE | 19,305 | 20 | Clean |
| LYNDEN WATER DEPARTMENT | 17,969 | 33 | Clean |
| LWWSD - SOUTH SHORE WATER SYSTEM | 10,028 | 107 | Clean |
| BIRCH BAY WATER & SEWER DISTRICT | 9,019 | 64 | Clean |
| BLAINE CITY OF | 6,319 | 141 | Clean |
| EVERSON CITY OF | 3,788 | 45 | Clean |
| Columbia Valley Water District | 2,648 | 39 | Clean |
| NOOKSACK WATER DEPT | 2,427 | 32 | — |
| GLACIER WATER DISTRICT | 2,383 | 14 | — |
| SANDY POINT IMPROVEMENT CO | 2,098 | 399 | — |
| DEER CREEK WATER ASSOC. | 2,000 | 15 | — |
| GLENHAVEN LAKES CLUB | 1,780 | 18 | — |
| SUMAS WATER DEPT | 1,740 | 77 | — |
| POLE ROAD WATER ASSOCIATION | 1,545 | 116 | — |
| MT BAKER SKI AREA - WHITE SALMON | 1,501 | 2 | — |
| POINT ROBERTS WATER DISTRICT NO 4 | 1,440 | 26 | — |
| WHATCOM COUNTY WATER DIST #7 | 1,410 | 3 | — |
| WHATCOM COUNTY WATER DIST #2 | 1,353 | 3 | — |
| NOOKSACK VALLEY WATER ASSOCIATION | 1,343 | 16 | — |
| Birch Bay Square Water Operation | 915 | 40 | — |
| MERIDIAN SCHOOL COMPLEX | 900 | 24 | — |
| NEWHALEM CAMPGROUND & VISITOR CTR | 800 | 1 | — |
| WHATCOM COUNTY WATER DIST 13 | 795 | 259 | Clean |
| MOUNT BAKER SCHOOL DISTRICT-DEMING | 700 | 27 | — |
| GLEN COMMUNITY ASSOCIATION | 623 | 43 | — |
| SUMAS RURAL WATER ASSOCIATION | 612 | 80 | — |
| MEADOWBROOK WATER ASSOCIATION | 579 | 36 | — |
| ACME WATER DISTRICT NO 18 | 568 | 35 | — |
| SILVER LAKE PARK - MAIN CAMPGROUND | 553 | 20 | — |
| OLD SETTLERS WATER ASSOCIATION | 540 | 39 | — |
| DEMING WATER ASSOC. | 501 | 21 | — |
| MOUNT BAKER WATER ASSOCIATION | 500 | 202 | — |
| LOUIE JOE WATER ASSOCIATION | 471 | 23 | — |
| DELTA WATER ASSOCIATION | 450 | 492 | — |
| PANORAMA POINT CAMPGROUND | 450 | 10 | — |
| SKOOKUM CHUCK WATER ASSOCIATION | 415 | 304 | — |
| BERTHUSEN ROAD WATER ASSOCIATION | 409 | 22 | — |
| DEMING LOG SHOW & RV | 407 | 27 | — |
| COLONIAL CREEK CAMPGROUND | 407 | 0 | — |
| MT BAKER SKI AREA HEATHER MEADOWS | 405 | 9 | — |
| GRANDVIEW-NORTHGATE INDUSTRIAL PARK | 400 | 7 | — |
| KENDALL ELEMENTARY SCHOOL | 400 | 22 | — |
| Northwest Water Assoc. Inc. | 400 | 221 | Detected |
| WHATCOM MEADOWS | 370 | 15 | — |
| Custer Water Association | 365 | 77 | — |
| LISECC | 357 | 40 | — |
| BELL BAY JACKSON WATER ASSOCIATION | 350 | 26 | — |
| HARMONY GRADE SCHOOL | 325 | 44 | — |
| Phillips 66 Company | 288 | 8 | — |