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Local water dashboard

Official source aggregation

Water quality in Castle Rock, WA 98611

A source-transparent look at local hardness, associated public water systems, EPA compliance history, and the measurements that are—and are not—available for Cowlitz County.

1 reported benchmark flag
Primary matched system
Castle Rock Municipal Water
Source water
Surface water
County
Cowlitz County
Profile updated

At a glance

What the current records say

Hardness

Soft

37.2 PPM · 2.2 GPG

Compliance screen

No active flag

0 active health-based records

Lead 90th percentile

0.005 mg/L

33% of action level

Utility match

1 system

Serves 4,367 people system-wide

Hardness meter

How hard is the water?

Soft

Estimated local hardness

USGS hardness classification scale

37.2 PPM

Soft
0–59Moderate
60–120Hard
121–180Very hard
181+

Parts per million

37.2

mg/L as CaCO₃ equivalent

Grains per gallon

2.2

1 GPG ≈ 17.1 PPM

What this means at home

At 37.2 PPM, mineral scale can build up on fixtures and heating elements, reduce soap lather, and leave visible spotting. Hardness is primarily an aesthetic and appliance concern—not itself a tap-water safety rating.

USGS sites used

15

Nearest site

16 mi

Observation range

Jan 7, 2016–May 19, 2026

Estimate confidence

Moderate

Median of the latest qualifying hardness observation at each nearby monitoring site. Nearest monitoring location: COLUMBIA RIVER AT PORT WESTWARD, NEAR QUINCY, OR (Tidal stream).USGS source documentation ↗

Regional context

Is 98611 typical?

These comparisons use other indexed ZIP estimates, not utility tap samples. They help show local context without replacing a household test.

Castle Rock median

37 PPM

About the same

1 indexed ZIP readings · Range 37.2–37.2 PPM

Washington median

104 PPM

67 PPM lower

189 indexed ZIP readings · Range 20.6–238 PPM

EPA benchmark screen

Contaminant snapshot

Available numerical results from associated SDWIS community water systems, compared with the applicable action level or federal MCL. Federal measured-value coverage is incomplete.

1 pass1 fail

Lead (PB90)

0.005 mg/L

Reported Dec 31, 2024

Copper (CU90)

1.4 mg/L

Reported Dec 31, 1993

Numerical coverage

2 comparable results

Missing values remain blank; absence is not treated as a pass.

Lead (90th percentile)

Measured in mg/L

Pass

Local 0.005

EPA limit 0.015

Local level is 33% of the listed EPA limit.

Copper (90th percentile)

Measured in mg/L

Fail

Local 1.4

EPA limit 1.3

Local level is 108% of the listed EPA limit.

Share of EPA benchmark

100% line = listed limit

EPA SDWIS compliance

Reported violation history

Open EPA source documentation ↗
2026Q2
All records
3
Health-based
0
Active health-based
0
Contaminant or ruleSystemStatusPeriod
Surface Water Treatment RuleWA5311800ResolvedMar 1, 2026through Mar 31, 2026
TTHMWA5311800ResolvedJan 1, 2023through Dec 31, 2023
Total Haloacetic Acids (HAA5)WA5311800ResolvedJan 1, 2023through Dec 31, 2023

No reported violation does not prove that every contaminant was tested or absent; SDWIS measured values are incomplete and lag state records.

Solutions matcher

Your personalized water action plan

Matched to Castle Rock ZIP 98611 using 37.2 PPM nearby hardness and 2 reported measurement benchmarks.

1 match

Drinking water protection

Under-Sink Reverse Osmosis System

Copper (90th percentile) has a measured benchmark flag or active health-based SDWIS record in this profile.

A certified multi-stage RO system targets a broader range of dissolved contaminants at the kitchen tap.

Explore under-sink filtration

Affiliate disclosure: we may earn a commission from qualifying purchases, at no added cost to you. Product matching is educational and does not replace certified water testing.

Frequently asked

Water questions for Castle Rock

Is tap water safe in Castle Rock?+

EPA ECHO shows no active health-based violation for the associated systems in this reporting snapshot. This does not prove every contaminant is absent; federal records can lag and household plumbing can change tap conditions.

How hard is the water?+

Nearby USGS observations produce an estimate of 37.2 PPM, or 2.2 grains per gallon, classified as soft. This is not a household tap measurement.

Do I need a water softener?+

There is no high-hardness trigger in this profile. Confirm with a tap test before buying equipment.