Johnston Co Rws& Swmd #4, OK
Exceeded the action level in the past
Latest 90th-percentile lead: 1.78 ppb (monitoring period 2025-2025). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. The latest result is under the action level, but this system has gone over 15 ppb before. Lead comes from pipes, not the source water, so a home with a lead service line can still be exposed. Test your own tap.
About Johnston Co Rws& Swmd #4
Johnston Co Rws& Swmd #4 serves about 600 people through 277 service connections, which makes it a small system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws groundwater, in Johnston County, Oklahoma. EPA system ID: OK2003503; phone on file: 580-937-4700. Ask them for your address in their service line inventory - every system had to publish one by Oct 2024.
Lead results over time
Against the period ending 2024 (1.68 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Johnston Co Rws& Swmd #4 is 43.6 ppb across 11 monitoring periods, 1 of them over the 15 ppb action level.
| Period ending | 90th-percentile lead |
|---|---|
| 2025 | 1.78 ppb |
| 2024 | 1.68 ppb |
| 2023 | 4.44 ppb |
| 2022 | 2.03 ppb |
| 2021 | 3.29 ppb |
| 2021 | 43.6 ppb over 15 |
| 2020 | 5 ppb |
| 2019 | 0 (not detected) |
| 2018 | 0 (not detected) |
| 2017 | 0 (not detected) |
| 2016 | 0 (not detected) |
Where this result ranks
Of the 870 Oklahoma systems with a lead result, the median latest reading is 0.81 ppb; 6 are over 15 ppb right now and 66 have gone over at some point. Johnston Co Rws& Swmd #4's 1.78 ppb sits at the 70th percentile in Oklahoma and the 67th nationally (higher means more lead).
Nearby utilities
9 other systems share Johnston County; 3 of them have a higher latest lead result than Johnston Co Rws& Swmd #4. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Tishomingo Municipal Authority | 3,000 | 0 (not detected) |
| Johnston Co Rwd #3 | 2,783 | 1.35 ppb |
| Murray State College | 1,150 | 0 (not detected) |
| Mannsville Public Works Authority | 587 | 5.88 ppb |
| Ravia | 459 | 2.37 ppb |
| Wapanucka | 420 | 1.64 ppb |
| Milburn Public Works Authority | 317 | 2.29 ppb |
| Mill Creek | 310 | 0 (not detected) |
| Bromide | 163 | 0 (not detected) |
Your move
Test your own tap with a certified lab first-draw sample; Coleman, OK may offer free or low-cost kits through the utility. If your own line is lead, replacing the private side runs about $1,200-$12,300 (EPA average about $4,700). Ask Johnston Co Rws& Swmd #4 whether it covers that cost before hiring anyone - many utilities now do.
These figures describe homes the utility sampled, not your tap. Only your service line record or a test of your own water answers the question for your house. The lead result guide covers how utilities pick the homes they sample. Why an old exceedance still matters: over the limit before, under it now.