West Slope Water District, OR
Exceeded the action level in the past
Latest 90th-percentile lead: 5.01 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. 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 West Slope Water District
West Slope Water District serves about 11,000 people through 3,234 service connections, which makes it a large system under EPA's size classes. It is owned by a local government (city, town, county or district) and draws surface water, in Washington County, Oregon. EPA system ID: OR4100660; phone on file: 503-292-2777. 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 (4.89 ppb) the latest result is about the same. The highest 90th-percentile result EPA holds for West Slope Water District is 21 ppb across 19 monitoring periods, 3 of them over the 15 ppb action level.
| Period ending | 90th-percentile lead |
|---|---|
| 2026 | 5.01 ppb |
| 2025 | 4.89 ppb |
| 2024 | 4.4 ppb |
| 2023 | 7.7 ppb |
| 2023 | 6.1 ppb |
| 2022 | 11.7 ppb over 10 |
| 2022 | 11 ppb over 10 |
| 2021 | 21 ppb over 15 |
| 2021 | 10.9 ppb over 10 |
| 2020 | 13.8 ppb over 10 |
| 2020 | 13 ppb over 10 |
| 2019 | 11.6 ppb over 10 |
| 2019 | 13.1 ppb over 10 |
| 2018 | 11.9 ppb over 10 |
| 2018 | 12.6 ppb over 10 |
| 2017 | 17 ppb over 15 |
| 2017 | 14.5 ppb over 10 |
| 2016 | 17.4 ppb over 15 |
| 2016 | 13 ppb over 10 |
Where this result ranks
Of the 909 Oregon systems with a lead result, the median latest reading is 1 ppb; 15 are over 15 ppb right now and 71 have gone over at some point. West Slope Water District's 5.01 ppb sits at the 90th percentile in Oregon and the 91st nationally (higher means more lead).
Neighbouring systems
28 other systems share Washington County; 2 of them have a higher latest lead result than West Slope Water District. If you are unsure which one supplies your house, the name on your water bill decides it.
| System | People | Latest lead |
|---|---|---|
| Tualatin Valley Water District | 224,600 | 5.3 ppb |
| Hillsboro, City Of | 92,632 | 0 (not detected) |
| Beaverton, City Of | 88,045 | 2.6 ppb |
| Tigard, City Of | 62,500 | 0.98 ppb |
| Tualatin, City Of | 28,106 | 4.93 ppb |
| Forest Grove, City Of | 26,838 | 3.6 ppb |
| Sherwood, City Of | 20,781 | 1.3 ppb |
| Cornelius, City Of | 14,490 | 0 (not detected) |
| Raleigh Water District | 4,500 | 5.01 ppb |
| North Plains Water Department | 3,663 | 0 (not detected) |
Your move
Test your own tap with a certified lab first-draw sample; Portland, OR 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 West Slope Water District 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. More in what a past exceedance means today.