Calculating the distance between points using polylines as the route.

[MichaelJJMaxwell]

I'm using ArcGIS Pro and trying to calculate the distance upstream of several points along a river network (Note this includes points along multiple tributaries). I have the river centerlines as a series of polylines in one layer, and the points along the river bank as another layer.

Doing this manually with the measure function isn't really feasible as there is over 30km of river spread across multiple tributaries, however with the amount of difficulty I've had with this it's quickly becoming the only reasonable option.

[DanPatterson]

split the polylines at your points, then calculate their lengths within the resultant featureclass's table

Split Line at Point (Data Management)—ArcGIS Pro | Documentation

[DuncanHornby]

RivEX, a geoprocessing toolbox for vector river networks can generate the metrics you require. It has several tools for measuring sites along river networks. If you just want the distance value then use the Find sites upstream of a site tool. If you want to visualise the line that links the two sites then use the Link Sites tool. Have a look at the worked examples to inspire your use of RivEX.