Rivers attract a distinctive kind of religious attention. Where mountains are venerated as presences, rivers are more often addressed as agents that receive, carry and return things.
Flow makes them useful for ritual
Moving water takes what is placed in it and does not give it back. That property gives ritual a physical action with an obvious meaning attached.
Practices of immersion, floating offerings and releasing ashes all depend on it. The river performs a removal that the participant can watch happening.
Still water does not do this, which is why pools and tanks tend to acquire different ritual roles, associated with reflection, containment and preparation rather than departure.
They are also boundaries
A river separates one bank from the other, and crossing it requires a ford, a bridge or a boat. The separation is real and daily.
Because of that, rivers appear throughout religious literature as thresholds, with the far bank standing for a changed condition rather than merely another place.
The image works because everyone listening had crossed a river and knew that the crossing is a moment with a before and an after.
Settlements depend on them visibly
Agriculture, drinking water, transport and trade cluster along watercourses. A community's dependence on a river is not abstract but observable each season.
Dependence of that scale reliably generates practices of gratitude, propitiation and calendar observance. Flood and drought are the same relationship going well or badly.
This also explains why river veneration frequently has an agricultural rhythm, with festivals fixed to the rise, the retreat or the first waters of the year.
Confluences receive special attention
The point where two rivers meet is treated as significant in a striking number of traditions, often more significant than either river alone.
A confluence is a place where something is completed, and it is unambiguous on the ground. Its location cannot be disputed the way a boundary can.
Sites of that kind accumulate shrines, bathing places and gatherings, and the accumulation is self-reinforcing once a route and a season are established.
Veneration and pollution sit together uncomfortably
Many venerated rivers are also heavily used, and the tension between ritual purity and physical contamination is a live question for the communities involved.
Some restoration efforts draw on religious language deliberately, since it can mobilise attention that regulatory argument does not reach.
Whether that framing produces durable results is disputed among those working on it, but the attempt shows how closely the sacred and the practical remain tied along a riverbank.