Delaware, OK
Lead detected, under the action levels
Latest 90th-percentile lead: 0.96 ppb (monitoring period 2026-2026). The federal action level is 15 ppb today and drops to 10 ppb in Nov 2027; EPA's health goal is 0. Lead was measured in sampled homes but the 90th percentile is under both action levels. EPA's health goal for lead is zero, so test your own tap if your home was built before 1986 or anyone in it is pregnant or a young child.
Who runs the water here
Delaware serves about 456 people through 358 service connections, which makes it a very small system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws surface water, in Nowata County, Oklahoma. EPA system ID: OK1021502; phone on file: 918-467-3218. Ask them for your address in their service line inventory - every system had to publish one by Oct 2024.
Every lead result on file
Against the period ending 2025 (0.99 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for Delaware is 0.99 ppb across 5 monitoring periods, none of them over 15 ppb.
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 0.96 ppb |
| 2025 | 0.99 ppb |
| 2023 | 0.6 ppb |
| 2019 | 0 (not detected) |
| 2016 | 0 (not detected) |
Against other Oklahoma systems
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. Delaware's 0.96 ppb sits at the 52nd percentile in Oklahoma and the 50th nationally (higher means more lead).
Nearby utilities
11 other systems share Nowata County; 6 of them have a higher latest lead result than Delaware. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Nowata Municipal Authority | 3,971 | 1.2 ppb |
| Consolidated Rwd #1 Nowata And Rogers Co | 1,580 | 0 (not detected) |
| Nowata Co Rwd #7 | 1,050 | 1.5 ppb |
| South Coffeyville | 790 | 2.7 ppb |
| Elm Bend Rwd Inc | 600 | 1.1 ppb |
| Nowata Co Rw & S Dist #1 | 500 | 2.1 ppb |
| Nowata Co Rwd #6 | 450 | 0 (not detected) |
| Lenapah Public Works Authority | 298 | 0 (not detected) |
| Nowata County Rwd # 3 | 225 | 0 (not detected) |
| Nowata Co Rwd #2 | 205 | - |
What to do in your house
Test your own tap with a certified lab first-draw sample; Delaware, 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 Delaware 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. Why sampled homes are the worst-case ones is in the guide to reading the number. The action level is dropping - the 10 ppb rule from 2027.