The Cleanest Water in Washington State

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Use the drop-down menu to examine the Top 10 or Bottom 10 testing stations, or use the Wildcard (*) option to view all available testing sites together.

The visualization above shows the ranking of the results of the latest Water Quality Index tests performed by the State of Washington. Washington State is known for its scenic mountain ranges, diverse climate, and crystal clear water and has published the following dataset, which tracks a number of metrics for the 2015 Water Quality tests performed by the Department of Ecology:

Metric Abbreviation Abbreviation Meaning Metric Weight
overallwqi_2015 Overall Water Quality Index (WQI) Score 1.00
wqifc Fecal Coliform count (mg FC / L H2O) .176
wqioxy Dissolved O2 (mg/L), ideally between 1-15 mg/L 0.187
wqiph Probability of Hydrogen (pH), ascending scale, 1-14 0.121
wqitemp Temperature Score for regularity 0.11
wqitp Total Phosphate (mg/L), essential compound for growth of plant and animal life in freshwater 0.11
wqitpn Total Persulfate Nitrogen (mg/L), contributes to animal and plant growth. 0.11
wqitss Total Suspended Solids (mg/L) 0.08
wqiturb Turbidity, a measurement which records the cloudiness of haziness of water in Nephelometric Turbidity Units (NTU) 0.09

These metrics all have individual weights applied based on their importance in the overall make-up of a body of water's health, and have been converted to a 0-100 ascending scale. Such a scale can be ambiguous to the amateur viewer, and so conversions to qualitative words have also been provided below:

Range Quality
90-100 Excellent
70-90 Good
50-70 Medium
25-50 Bad
0-25 Very Bad

More information about the Water Quality Index, its methodology, or metrics, can be found here

Use the ChartLab visualization below, and the dropdown menus at the top of the screen to choose the desired metric, and compare the Top 10, Top 20, or Top 30, Bottom 10, Bottom 20, or Bottom 30 testing sites, or use the Wildcard option to view all available testing sites together.

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The map below shows the Top 10 Overall Best WQI site locations noted in blue, and the Bottom 10 Overall Worst WQI site locations noted in red. The Station ID for each site is contained in the metadata, and may be returned with this SQL query in the Axibase TSD SQL Console and then cross-referenced to the Department of Ecology's own map (linked here):

SELECT tags.station_name AS "Station Name", value AS "WQI Overall Score", tags.station AS "Station Code"
  FROM "overallwqi_2015"
ORDER BY value DESC
  LIMIT 10

Highest Water Quality Test Sites

Station Name WQI Overall Score Station Code
Abernathy Cr nr mouth 99 25E060
Hamma Hamma R @ Lena Creek Camp 94 16B130
Twin Cr @ Upper Hoh Rd Br 94 20E101
Methow R @ Twisp 92 48A140
Skokomish R nr Potlatch 91 16A070
Cedar R nr Landsburg 91 08C110
Little Pend Oreille R nr NatWildRef 89 59B200
Duckabush R nr Brinnon 88 16C090
Yakima R @ Umtanum Cr Footbridge 88 39A055
Columbia R @ Umatilla 88 31A070
SELECT tags.station_name AS "Station Name", value AS "WQI Overall Score", tags.station AS "Station Code"
  FROM "overallwqi_2015"
ORDER BY value ASC
  LIMIT 10

Lowest Water Quality Test Sites

Station Name WQI Overall Score Station Code
NF Stillaguamish R @ Cicero 29 05B070
SF Palouse R @ Pullman 34 34B110
Palouse R @ Hooper 37 34A070
Hangman Cr @ Mouth 39 56A070
Crab Cr nr Beverly 42 41A070
NF Stillaguamish R nr Darrington 43 05B110
Nooksack R @ Brennan 45 01A050
Palouse R @ Palouse 45 34A170
Walla Walla R nr Touchet 49 32A070
Yakima R @ Kiona 49 37A090

Find your favorite waterway in the data above, or discover a new one and enjoy all the natural beauty that Washington has to offer.