| HIGHLANDS MUTUAL WATER COMPANY | 7,772 | 23 | Detected |
| HIDDEN VALLEY LAKE CSD | 6,235 | 2 | Detected |
| KONOCTI COUNTY WATER DISTRICT | 5,928 | 3 | Detected |
| LAKEPORT, CITY OF | 4,762 | 9 | Detected |
| GOLDEN STATE WATER CO.-CLEARLAKE SYSTEM | 4,644 | 2 | Detected |
| MT. KONOCTI MUTUAL WATER COMPANY | 4,360 | 14 | Detected |
| KELSEYVILLE CO WATERWORKS DISTRICT 3 | 4,102 | 0 | Clean |
| LAKE COUNTY CSA 21 - NORTH LAKEPORT | 4,046 | 5 | — |
| COBB AREA COUNTY WATER DISTRICT | 3,515 | 12 | — |
| NICE MUTUAL WATER COMPANY | 2,929 | 6 | — |
| CLEARLAKE OAKS COUNTY WATER DISTRICT | 2,359 | 21 | — |
| LUCERNE WATER CO. - CAL WATER SERVICE | 2,129 | 10 | Detected |
| LAKE COUNTY CSA 20 - SODA BAY | 2,003 | 1 | — |
| CALLAYOMI COUNTY WATER DISTRICT | 1,598 | 8 | — |
| LAKE COUNTY CSA 2 - SPRING VALLEY | 1,531 | 23 | — |
| BUCKINGHAM PARK WATER DISTRICT | 1,521 | 24 | — |
| LOWER LAKE COUNTY WATER DISTRICT | 1,326 | 12 | — |
| LAKESIDE COUNTY PARK | 1,000 | 12 | — |
| UPPER LAKE COUNTY WATER DISTRICT | 989 | 7 | — |
| ROTTEN ROBBIE | 899 | 4 | — |
| LOCH LOMOND MUTUAL WATER CO | 693 | 26 | — |
| HARBOR VIEW MUTUAL WATER COMPANY | 550 | 73 | — |
| LAKE COUNTY CSA 13 - KONO TAYEE | 449 | 4 | — |
| HARBIN HOT SPRINGS | 401 | 20 | — |
| LAKEPORT CINEMAS | 400 | 16 | — |
| ANDERSON SPRINGS CSD | 373 | 31 | — |
| HUTTOPIA SIX SIGMA CAMPGROUND | 370 | 0 | — |
| CACHE CREEK VINEYARDS | 310 | 0 | — |
| GLENHAVEN MUTUAL WATER COMPANY | 300 | 19 | — |
| KONOCTI SHORES | 277 | 26 | — |
| CAL 20 VILLAGE AND MEADOW POINTE PARK | 255 | 30 | — |
| CLEAR WATER MUTUAL WATER COMPANY | 252 | 46 | — |
| LE TRIANON RESORT | 243 | 24 | — |
| MANDALA WATER SYSTEM | 212 | 18 | — |
| WESTGATE PETROLEUM | 210 | 4 | — |
| SARATOGA SPRINGS RETREAT CENTER | 208 | 8 | — |
| REEL IN RESORT | 200 | 40 | — |
| WALNUT COVE MOBILE ESTATES | 200 | 22 | — |
| JITTER BEAN COFFEE | 160 | 4 | — |
| KONOCTI HARBOR RESORT | 155 | 9 | — |
| PIER 1900 HOMEOWNER'S ASSOCIATION | 152 | 7 | — |
| BELLA LAGO MOBILE HOME PARK | 152 | 33 | — |
| CORINTHIAN BAY MUTUAL WATER COMPANY | 150 | 21 | — |
| LAKE PILLSBURY RESORT & MARINA INC | 150 | 24 | — |
| LARSEN'S OFFICE COMPLEX | 112 | 17 | — |
| USFS-SUNSET POINT CAMPGROUND | 110 | 3 | — |
| THOMAS WATER SYSTEM | 110 | 2 | — |
| WESTWIND MOBILE HOME PARK | 104 | 45 | — |
| LODGE AT BLUE LAKES | 100 | 12 | — |
| CDF-KONOCTI CONSERVATION CAMP NO. 27 | 100 | 29 | — |