Streamflow Alteration Index (SAI) v1.0 Database for Ontario, Canada

The Streamflow Alteration Index (SAI) v1.0 database provides a spatially continuous, network-based, subbasin-scale screening product for potential streamflow alteration across Ontario, Canada. The dataset was developed using the Ontario Lake and River Routing Product Version 2 (OLRRP v2) routing network and an inventory of alteration signal sources associated with upstream dams, reservoirs, waterpower facilities, and lockstations. SAI includes two paired indices: SAI_I (0–100%), representing alteration associated with confirmed (Level I) signal sources, and SAI_II (0–100%), representing alteration associated with potential (Level II) signal sources. The dataset is intended as a screening product for hydrologic and aquatic applications and should be interpreted as indicating the presence and potential influence of instream alteration rather than the exact hydrologic magnitude of alteration. This release contains three primary data products: ontario_subbasin_sai_v1-0.shp: subbasin polygon layer containing SAI values for all subbasins in the OLRRP v2 network ontario_river_v2-0-1.shp: river polyline layer containing SAI values for river reaches in the OLRRP v2 network ontario_alteration_signals.csv: table of Level I, Level II, and Level III alteration signal sources used in the SAI workflow The GIS layers are provided in the NAD 1983 Ontario MNR Lambert coordinate reference system. The subbasin and river layers follow the OLRRP v2 identifier schema and can be linked to OLRRP-derived attributes through SubId and related network identifiers. The alteration signal table includes harmonized identifiers, source provenance, geographic coordinates, and Level I/II/III classification flags. Current access status: Restricted during manuscript review and pre-publication preparation. The dataset will be made openly available upon publication of the associated manuscript. During manuscript review, an example interactive map for the Southeast (SE) drainage region is available here. A full Ontario interactive map will be released upon publication. Related base routing product: Shen, H., Han, M., Tolson, B., and Metcalfe, R. A.: The Ontario Lake and River Routing Product Version 2 (OLRRP V2), https://doi.org/10.5281/zenodo.14225103, 2024.