Guelph Stormwater Basins

A reference layer of the stormwater management basins published by the City of Guelph — 93 wet ponds, dry and infiltration basins and constructed wetlands — with the City's creek corridors drawn faintly behind them, ready to add to the OpenStreetMap editors iD and JOSM while you map.

City data: 2026-10-09 · tiles rebuilt: 2026-10-09

Contains information licensed under the Open Government Licence – City of Guelph. Sources: Stormwater Management Pond, Watercourse Polygons.

Preview

The raster layer drawn over OpenStreetMap. solid blue: a wet pond, which holds a permanent pool. pale blue, hatched: a dry or infiltration basin, a grass hollow that holds water only after a storm. teal: a constructed wetland. The faint grey-blue wash is a creek corridor, labelled where the City names the creek.

Coverage vs OpenStreetMap: see which City basins are missing from OSM or mapped as plain water, and which named creeks run unnamed in OSM — a mapper's worklist with an interactive map and table.

Two layers — which to use

Vector layer	Interactive, in two layers: `basins` (click one to read `kind`, `type`, `area`, `fenced`, `installyear`, `ownedby`, `locdesc`, `plan`) and `watercourses` (`name` where the City has one). Best in iD.
Raster layer	Basins coloured by kind, creek corridors and creek names drawn on the tiles. A readable backdrop. Best in JOSM.

Which tag? A wet pond takes natural=water + water=basin — the scheme Guelph's mapped ponds already use — optionally with basin=retention. A dry basin is not water: map it as landuse=basin + basin=detention, and an infiltration basin as landuse=basin + basin=infiltration. How a constructed wetland should be tagged is not settled; leave what is there.

The City's plan is not a name. It is the subdivision plan the basin was built under (“Plan 680 – Hanlon Industrial Park – Phase 2”). It is there to help you find the basin in City documents — do not copy it into name. Creek names are the opposite case: those are real names.

Add to iD

Vector layer (interactive)

Open the iD editor and press U for the Map Data panel.
Under Custom Map Data, open the settings and paste this URL:

https://guelph-maps.github.io/guelph-water-layer/tiles/vector/{z}/{x}/{y}.pbf

Zoom in, then click any basin to see its tags in the inspector.

Raster layer (colours and creek names)

Open the Background panel and choose Custom.
Paste this URL template:

https://guelph-maps.github.io/guelph-water-layer/tiles/raster/{z}/{x}/{y}.png

Add to JOSM

Raster layer (recommended for JOSM)

Open Preferences → Imagery and click +TMS.
Paste this entry (the tms[13,17] prefix sets the zoom range; JOSM scales it up past z17):

tms[13,17]:https://guelph-maps.github.io/guelph-water-layer/tiles/raster/{zoom}/{x}/{y}.png

Give it a name such as Guelph Stormwater Basins, click OK, then enable it from the Imagery menu. Note JOSM's placeholder is {zoom}, not {z}.

Vector layer (optional)

JOSM can also add the vector tiles via Preferences → Imagery → +MVT:

https://guelph-maps.github.io/guelph-water-layer/tiles/vector/{zoom}/{x}/{y}.pbf

Notes

Of the City's 152 rows, the 93 that are basins of 500 m² or more are drawn. Left out: 37 Greenway swales (grassed ditches along lot lines), one buried rock trench, seven rows with no type, and 14 basins under 500 m² — infiltration galleries too small to see on imagery.
Every watercourse polygon the City publishes is drawn; 13 of the 71 carry a creek name.
Vector tiles are pre-rendered through zoom 19; raster tiles for z13–17 (the editor overzooms them further).
Tiles are refreshed weekly from the City's service.
This is a reference layer — verify against imagery before copying anything into OpenStreetMap. A dry basin is a grass hollow and often fenced (the City records fenced); trace the hollow you can see, not a parcel.