The basin boundary file used by Leaflet must apparently be in WGS84 and Emma made sure of this by doing a conversion of the original SNODAS_BasinBoundaries.shp file in QGIS. However, it should be possible to convert the basin boundaries file from any projection to what is needed for the web app. See: http://kartena.github.io/Proj4Leaflet/. When there is time... the web app should check that it is properly handling the projection... either allow a conversion, or complain if the basin boundary layer is not the expected conversion. Note that reprojecting on the fly is a performance hit so it is probably best to get the original into the desired projection before doing serious other work.
The basin boundary file used by Leaflet must apparently be in WGS84 and Emma made sure of this by doing a conversion of the original SNODAS_BasinBoundaries.shp file in QGIS. However, it should be possible to convert the basin boundaries file from any projection to what is needed for the web app. See: http://kartena.github.io/Proj4Leaflet/. When there is time... the web app should check that it is properly handling the projection... either allow a conversion, or complain if the basin boundary layer is not the expected conversion. Note that reprojecting on the fly is a performance hit so it is probably best to get the original into the desired projection before doing serious other work.