01The verdict: is Coulee Dam water safe?
Coulee Dam's tap water meets most EPA standards but has areas that warrant attention. With a grade of A (90.7/100), some contaminant levels or compliance issues suggest that residents may benefit from additional filtration. The city's 1 water system serves approximately 1,359 residents using surface water (rivers, lakes, or reservoirs).
1 unresolved violation on record
EPA records show an open compliance item for this system. Most are administrative, but unresolved items are worth watching.
See what was cited ↓Lead is well under the limit
90th-percentile lead is 1.7 ppb — beneath the 15 ppb federal action level and under the 5 ppb watch threshold.
See the trend ↓A flood-prone service area
4 federal disaster declarations on record. After severe weather, watch for boil-water advisories.
See the risk factors ↓Coulee Dam's drinking water received a grade of A (90.7 out of 100), indicating excellent water quality. The city's 1 water system serves approximately 1,359 residents using surface water.
Lead levels were measured at 1.7 ppb (90th percentile), well within EPA limits. This system has not yet been tested for PFAS under the EPA UCMR 5 program. The system has 3 violations on record, including 1 health-based violation. 1 remains unresolved.
Coulee Dam ranks #35 out of 294 cities in Washington for water quality, placing it above average in the state. The city draws from surface water sources, which are more susceptible to seasonal runoff and agricultural contamination, requiring extensive multi-barrier treatment including coagulation, filtration, and disinfection. As a small community water system, Coulee Dam may have fewer resources for advanced treatment technologies and infrastructure upgrades compared to larger utilities.
02What's in Coulee Dam's water
Every contaminant flagged in Coulee Dam, on one shared scale: distance to its own legal limit. The red line is the limit — anything past it is out of compliance, and the closer a bar gets, the less headroom the system has.
Full contaminants report
| Contaminant | Detected Level | EPA Limit | Unit | Category | Status |
|---|---|---|---|---|---|
| Lead (90th percentile) LeadHeavy Metal A toxic heavy metal that can leach into drinking water from older pipes, solder, and fixtures. No amount of lead in water is considered safe. Health EffectsBrain and nervous system damage in children, kidney damage, high blood pressure, and reproductive problems in adults. EPA Limit15 ppb action level Common SourcesCorrosion of lead pipes, lead solder, brass faucets, and household plumbing. | 1.7 | 15 | ppb | Inorganic | Safe |
Cities ranked by 90th-percentile lead PF PFAS in Washington
Cities ranked by compounds detected Cu Copper in Washington
Cities ranked by 90th-percentile copper
03Coulee Dam's ten-year track record
Each box is one year. A green check means no EPA violations; a numbered badge counts that year's violations — red if any were health-based, amber if they were monitoring or paperwork issues. The system has 3 violations on record, including 1 health-based violation. 1 remains unresolved.
All ten of the last ten years were clean — no EPA violations recorded for Coulee Dam.
▼ Down 0.30 ppb since 2004. Latest reading: 1.7 ppb (2023) — 11% of the action level. Sampled at higher-risk homes (90th percentile).
04Where Coulee Dam's water comes from
Coulee Dam's drinking water comes primarily from surface water sources such as rivers, lakes, or reservoirs.
Surface Water
Rivers, lakes, or reservoirs — more exposed to runoff, agriculture, and seasonal swings than groundwater.
Local treatment
Multi-barrier treatment: coagulation, sedimentation, filtration, and disinfection to meet EPA standards.
1 system
1 water system (1 wholesaler), operated under local government ownership.
1,359 people
Residents served across Coulee Dam's service area.
Surface water systems require multi-stage treatment including coagulation, sedimentation, filtration, and disinfection to meet EPA Safe Drinking Water Act standards. These sources can be impacted by seasonal changes, stormwater runoff, upstream agriculture, and industrial discharge. The system is operated by local government ownership and serves approximately 1,359 people through 1 water system.
| System name | PWSID | Population | Source |
|---|---|---|---|
| COULEE DAM WATER DEPT | WA5315400 | 1,359 | Surface Water |
Water bodies near Coulee Dam
As a surface-water system, these water bodies may directly influence Coulee Dam's drinking water supply.
05Pressure on Coulee Dam's watershed
Outside forces that shape what reaches the treatment plant. None of these is a verdict on the tap by itself — but each adds pressure worth knowing about.
Flood & storm history
4 federal disaster declarations on record for Okanogan County. Flooding and severe storms can overwhelm treatment plants, cause sewage overflows, and push runoff into supplies.
Drought
Okanogan County is in D3 (extreme drought) per the U.S. Drought Monitor (week of Jul 2026). Drought can raise disinfection-byproduct levels and taste/odor issues as utilities draw from lower reservoirs.
06How Coulee Dam compares
Scores for nearby Washington cities on one line, with the average marked.
dashed line = Washington average (53/100)
Coulee Dam scores 90.7/100 — above the Washington average of 53/100. It outscores 9 of 10 nearby cities. Full Washington rankings →
42.3 / 100FTacoma, WA
32.2 / 100FVancouver, WA
32.9 / 100FSpokane, WA
39.2 / 100FKent, WA
44.4 / 100ABellevue, WA
91.6 / 100
Compare all cities in the county — grades, violations, and contaminant data side by side.→
07What to do at home
Steps matched to what testing actually found in Coulee Dam's water — not generic advice.
A basic carbon filter still helps
Coulee Dam's water meets federal standards, but a simple carbon filter improves taste and adds a margin of safety against short-term issues.
Compare tested filters →Read your utility's annual report
Every utility must publish a yearly Consumer Confidence Report with its own testing results. It pairs well with the independent data on this page.
How to read a CCR →Watch for Coulee Dam alerts
This area has a history of flood declarations — after severe weather, watch for boil-water advisories from the utility, and check the live alerts on this page.
All water alerts →Frequently asked questions
Is Coulee Dam, WA tap water safe to drink?
Coulee Dam's water quality earned a grade of A (90.7/100). The water generally meets EPA standards and is considered safe for consumption. The city ranks #35 out of 294 cities tested in Washington.
What contaminants are in Coulee Dam's water?
Lead was measured at 1.7 ppb (90th percentile). 3 violations are on record.
How is Coulee Dam's water quality grade calculated?
The grade is based on four factors: violation history (40%), lead and copper levels (25%), PFAS contamination (25%), and regulatory compliance (10%). The score is also adjusted based on how complete the available data is. See our methodology page for full details.
Do I need a water filter in Coulee Dam?
Based on current data, basic filtration should suffice for additional peace of mind.
Where does Coulee Dam's water come from?
Coulee Dam's water is sourced from Surface water. The city has 1 water system serving approximately 1,359 residents.
What health violations has Coulee Dam's water system had?
Coulee Dam has 1 health-based violation on record. The most recent violation was recorded in July 2015. Health-based violations mean the water exceeded EPA maximum contaminant levels (MCLs) for a regulated substance. 1 violation remains unresolved.
How does Coulee Dam's water compare to other cities?
Coulee Dam ranks #35 out of 294 cities in Washington (better than 88% of state cities) and #2081 out of 15382 cities nationally (87th percentile). The grade of A reflects the combined assessment of violation history, lead and copper levels, PFAS contamination, and regulatory compliance.
Does Coulee Dam's small water system affect quality?
Coulee Dam's system serves approximately 1,359 residents. Small community water systems (under 3,300 people) may have fewer financial resources for infrastructure upgrades and advanced treatment technologies. However, they are held to the same EPA drinking water standards as larger systems. This system has 3 violations on record.