Field notes · sources & method
Show the work.
Then draw the line.
How we computed the buffer numbers
Computed 2026-10-10 from the City of Walla Walla's and Walla Walla County's own public GIS services. Nothing here is an official determination; see the disclaimer on the map.
Read this map in three parts
The band comes from the City's mapped stream centerlines. Your lot comes from County parcel records. The rule comes from the draft ordinance. A map comparison helps you ask a better question; a site survey and the City determine the regulated line.
Go to the numbers and their sources ↓What the map shows
The photographic background is USDA / USGS aerial imagery from The National Map. Image dates vary; these are not live photographs. Switch to Street map for a simpler background. The choice changes only the background: City and County GIS still supply the bands, boundaries and parcel results.
- Stream centerlines and the 100-ft buffer band are read live, every time the page loads, from the City of Walla Walla GIS Group's public map service
WW_Streams_Riparian_Buffer(published 2026-10-06). The 100-ft band is the City's own polygon, named by the City "Visible Streams Buffer 100 Feet From Stream Centerline." - The 35, 50, 75 and 150-ft comparison bands are computed in your browser by offsetting the same City centerlines (Turf.js). They are for comparison only.
- Parcels are read live, one at a time, from Walla Walla County's public Tax Parcels service. The share of a parcel inside the band is computed in your browser from the parcel polygon and the band polygon.
- No City or County geometry is copied to this website.
Where the rules change: city, County, College Place, Mill Creek
- You are in: every check first locates the point. Inside the City's own limit rings (even-odd test on the City's 2026-10-06 limit layer; it reproduces the City's 9,029-acre figure exactly) the proposed CAO band applies. Otherwise the County's City_Limits and Urban_Growth_Areas polygons decide between College Place, a UGA (unincorporated, County rules) and unincorporated county.
- Outside city limits the card tests the point and lot against Walla Walla County's working riparian buffer layer (published 2026-08-31; tiered 35/50/75/100 ft per reach via its
buff_distattribute) and names the nearest County-mapped stream. The County has not published a draft ordinance or hearing dates; its periodic update is due 2026-12-31. The layer is a preview, not a rule. - College Place has its own critical-areas code and no public buffer layer; the map shows only its boundary.
- Mill Creek is excluded from the draft CAO ("See SMP"). It is drawn from the County hydrography layer (name MILL CREEK / MILL CREEK (CHANNEL)) for the in-city reach, with the Shoreline Master Program's 35-ft flood-channel buffer (SMP Table 6.5-1, Gose St to the Bennington Lake diversion) and the 200-ft shoreline jurisdiction noted on the card. We do not claim SMP widths for reaches outside the flood channel; the SMP PDF could not be text-extracted for this check (see research/05).
Coverage check: what the City layer leaves out
Inside city limits, County hydrography holds 27.9 stream-miles and DNR 28.7, against the City's 17.9. Of the County miles, 63.9% lie within 50 ft of a City centerline; the rest, longer than 300 ft, are (full table in research/07-coverage-check.md):
| Reach (County layer) | Length without a City line (ft) | Likely reason |
|---|---|---|
| Mill Creek (channel), three pieces: Wilbur Ave, 6th Ave/Sumach St, Myra Rd | 28,170 | Excluded from the CAO; Shoreline Master Program (35-ft flood-channel buffer) |
| Lincoln Creek, W Poplar St / S 11th Ave | 8,606 | Not in the City's visible-streams layer: piped or culverted reach (verify with City GIS) |
| Butcher Creek, Hwy 12 / N 7th Ave and Rees Ave / Sumach St | 5,858 | Piped / culverted reach (verify) |
| Bryant Creek, Coast Guard Dr / Parade Loop (VA campus) and McAuliff Ave / Chestnut St | 4,906 | Not digitized by the City; likely piped through the VA grounds (verify) |
| Owen Spring, Valencia St / Isaacs Ave | 788 | Spring run not in the City layer |
| Garrison Creek, S Division St / E Chestnut St | 391 | Short gap in the City line at Division St (culvert) |
These County-only reaches can be switched on in the Layers panel ("County-mapped reaches not in the City's layer"), and the result card says so when one lies within 150 ft of the point checked; the City's draft would not buffer them unless the City adds them.
The short blue stubs on the map are real City segments: the one at Francis Ave / S Division St is StreamName "Unknown" (subtype 5, a spring, 167 ft); the stubs around Whitman College (Boyer Ave / Merriam St, Stanton St / University St) are College Creek (73 and 555 ft); Barber Creek and Butcher Creek appear as a dozen 40–400 ft pieces between Figueroa St and E Rees Ave where they surface between piped sections; Owen, Peter and Gose springs are subtype-5 spring runs. DNR adds a further set of unnamed intermittent lines (mostly along Hwy 12 and Myra Rd) and two perennial ditches (Bush St / Garrison St; Oxford St / University Dr) that neither the City nor the County maps as creeks.
The numbers on the stats strip
Computed offline on 2026-10-10 with GeoPandas/Shapely in Washington State Plane South (EPSG:2927, US survey feet). City limits: Walla Walla County GIS "City Limits" polygon (9,103.5 acres; the City's own line layer says 9,029 acres).
| Buffer width (from centerline) | Acres inside city limits | City parcels touching the band |
|---|---|---|
| 35 ft (roughly today's standard on most creeks) | 163.2 | 982 |
| 50 ft | 236.0 | 1,064 |
| 75 ft | 357.3 | 1,307 |
| 100 ft (proposed), recomputed from City centerlines | 476.9 | 1,489 |
| 100 ft, the City's own published polygon | 479.3 | 1,490 |
| 150 ft | 708.8 | 1,881 |
- Stream miles: 17.93 miles of the City's "visible streams" fall inside city limits (Garrison 4.81, Stone 3.45, Yellowhawk 2.45, Bryant 1.52, Butcher 0.88, Stone N. Fork 0.79, Lincoln 0.56, College 0.56, Titus 0.50, Caldwell 0.43, Stone S. Fork 0.41, Russell 0.29, plus springs and short reaches). Mill Creek is not in the City layer because it is regulated under the Shoreline Master Program, not the CAO.
- Parcels touched = Walla Walla County tax parcels whose polygon intersects the band and whose center lies inside city limits (12,582 such parcels in total). "Touching" includes lots the band clips by only a few feet, and street and park parcels.
- The recomputed 100-ft band and the City's published polygon differ by only 2.4 acres, so the City buffered the same centerlines the same way.
Reconciling with the City consultant's figures
The City's consultant (Facet, July 2026) reports the buffer area growing from 268.8 to 757.4 acres on 43.2 stream miles (29.7 open + 13.5 piped). The map's band is 477 acres on 17.9 miles.
These are both the City's numbers, and they measure different things. Facet's stream network is roughly 2.4 times longer than the City's Oct 6 "visible streams" layer: it includes piped reaches (13.5 miles), and, by its length, additional open reaches that the visible-streams layer does not draw (the USGS National Hydrography Dataset shows about 36 miles of flowlines inside city limits, and County hydrography about 28). 43.2 miles buffered 100 ft on each side is about 1,047 acres before accounting for overlaps and the city boundary, which is consistent with Facet's 757 acres inside the city. The map band should therefore be read as the minimum extent on mapped open channels; the consultant's figure is the broader estimate the City is working from.
A figure of "1,100 acres" that has circulated is not in any City document we found; 42 miles corresponds to Facet's 43.2.
Caveats
- Centerline vs. ordinary high-water mark. Every band on this map, including the City's own, is measured from a digitized stream centerline. The draft ordinance measures from the ordinary high-water mark, top of bank, or channel migration zone, whichever is greater. For a channel 20 to 60 ft wide, the regulated edge is 10 to 30 ft farther out than drawn. That is why the result card flags lots within 150 ft as "possibly affected."
- Positional accuracy. The City's centerlines are attributed "Placed on Map" (digitized from imagery, not surveyed). Expect tens of feet of uncertainty; a result within about 30 ft of a threshold should be treated as undetermined.
- Which streams. The City layer draws visible open channels inside city limits only: it omits Mill Creek, piped reaches, and all streams in the unincorporated Urban Growth Area, although the draft ordinance also covers "intermittent open channels between piped sections" and the UGA. The City's layer contains every creek named in draft Table 6 except Reser Creek, which lies outside city limits; it also includes Butcher, Lincoln, College, Barber and Kathy creeks, three springs and one short irrigation segment under the draft's 'and others within city limits' language, and it excludes Mill Creek (Shoreline Master Program). Audit (2026-10-10,
data/scripts/audit_streams.py): 61 segments, 17.94 miles, all inside city limits; one segment flagged intermittent. Outside city limits the map returns "outside city limits" rather than a distance: we deliberately do not add County or State hydrography for the growth area, because it is different data under different (County) rules. - Parcel data is the County Assessor's working layer (2026-09-28). Owner names are never requested or displayed.
- Only the City of Walla Walla can determine whether a specific property is subject to critical-areas rules. Confirm with Development Services (509-524-4710, permits@wallawallawa.gov).
Sources and reproducibility
Every layer is read live in your browser from a public map service (nothing is copied to this site). Payloads are generalized server-side to about 2 m for the City + UGA area; sizes measured 2026-10-10.
| Layer (panel name) | Service | Fields used | Size / when fetched |
|---|---|---|---|
| City-mapped streams; City proposed 100-ft band; City limits | services1.arcgis.com/F8n8WJgK0mEjXgtm/.../WW_Streams_Riparian_Buffer/FeatureServer layers 0, 1, 2 (City of Walla Walla GIS, 2026-10-06) | StreamName, Intermittent, Subtype; BUFF_DIST; NAME, GIS_ACRES | 0.22 + 0.93 + 0.06 MB, on load |
| Parcels (zoom in); address search; click-to-parcel | services8.arcgis.com/COL6rRPkF9w28VGX/.../Tax_Parcels/FeatureServer/0 (County Assessor, 2026-09-28) | geo_id, prop_id, full_situs, situs_*, size_acres, link (never owner fields) | per parcel / per view at zoom 16+ |
| College Place limits; jurisdiction | .../City_Limits/FeatureServer/0 (County GIS) | name | 25 KB, on load |
| Urban Growth Area boundary; unincorporated shading; jurisdiction | .../Urban_Growth_Areas/FeatureServer/0 (County GIS) | name | 16 KB, on load |
| County working buffer (Aug 2026, tiered 35–100 ft) | .../Minimum_Riparian_Buffer/FeatureServer/0 "WallaWallaCounty_Minimum_Riparian_Buffer_20260831" (County GIS) | name, buff_dist | ~0.5 MB, on load (default on) |
| County-mapped streams; Mill Creek (SMP) | .../Hydrologic_Features/FeatureServer/0 (County GIS, 2021) | name | ~0.35 MB, on load (default on) |
| County zoning districts | .../Zoning/FeatureServer/0 (County GIS; unincorporated + UGA only) | zon_abbrev, zoning, jurisdicti | 0.2 MB, first time switched on |
| Floodplain (FEMA Q3 via County, legacy) | .../FEMA/FeatureServer/0 (County GIS). Walla Walla County is not in FEMA's digital NFHL. | zone, floodway, sfha | ~0.4 MB (zones other than X), first time switched on |
| DNR watercourses (water type) | gis.dnr.wa.gov/site2/.../WADNR_PUBLIC_FP_Hydro/MapServer/0 (WA DNR Forest Practices) | WC_GNIS_NM, FP_WTRTY_CD, WC_PERIOD_LABEL_NM | ~0.65 MB, first time switched on |
| Zoning inside the two cities | No public City of Walla Walla or College Place zoning map service exists (the City publishes a 2013 PDF only), so the panel offers County zoning alone. | ||
- City of Walla Walla Critical Areas Ordinance page (the City's interactive map embeds the same service).
- City of Walla Walla Shoreline Master Program (Dec 2023), Appendix A Table 6.5-1: 35-ft buffer on the Mill Creek flood channel; shoreline jurisdiction 200 ft.
- Cross-checks: USGS National Hydrography Dataset (HUC8 17070102) and WA DNR Forest Practices hydrography. Processing script, raw downloads and the full data inventory are in the project repository (
data/scripts/,research/03-gis-data-inventory.md,research/07-coverage-check.md).
Optional comparison · not a forecast
What if a 100-foot buffer applied here?
The separate what-if switch helps residents outside city limits see the size of a wider band. It does not show an adopted County rule, establish a pending County proposal or predict that one will pass. The County’s 2026 periodic-update project charter, page 5, includes a critical-areas update; it does not establish a blanket 100-foot width.
Today and proposed: the current City code, Table 6, lists 35-foot buffers for most named creek reaches and 50 feet for the listed Yellowhawk reach, subject to exceptions. The City draft proposes 100 feet per side and a separate 15-foot building setback. Unincorporated land and College Place have their own applicable rules. The County’s working buffer GIS layer is a separate reference, not proof of an adopted rule.
How the preview is drawn: on request, the browser reads the County’s live Hydrologic Features and City Limits data. It computes 100 feet on each side of mapped centerlines, clips away incorporated cities, and excludes named Mill Creek reaches. The dashed red overlay is an illustration; no 15-foot setback is added. The geometry stays in your browser.
Coverage: this preview covers the valley rectangle from 118.52° W to 118.14° W and 45.96° N to 46.16° N, the same working area used for the map’s County context. It is not countywide or statewide. Geometry is generalized to roughly 2 meters by the service, as in the existing County context layers. The preview compares only the selected point, not the whole parcel. A blank area can reflect missing mapped waterways and does not establish that a property is unregulated. Other shoreline reaches, wetlands and site-specific exceptions are not evaluated.
What a wider rule could mean: if adopted in your jurisdiction, a wider buffer could affect the room available for new structures, additions and subdivisions. Actual restrictions, existing-use protections and exceptions would depend on the adopted wording and a site determination. Centerlines do not locate the ordinary high-water mark, top of bank or channel migration zone used in regulatory measurements. Ask the responsible planning office for the rule and measurement that apply to your lot.
The regular property result and City statistics do not change when this overlay is on. The 35/50/75/100/150 buttons still control only the City band. A copied link retains an enabled scenario as #whatif-100, and the hypothetical label remains visible in the map key.
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