Which preposition to use with esk

in Occurrences 2%

To see the valley of the Esk in its richest garb, one must wait for a spell of fine autumn weather, when a prolonged ramble can be made along the riverside and up on the moorland heights above.

at Occurrences 1%

The confluence with the Esk at Grosmont is lost in a haze of smoke and a confusion of roofs and railway-lines; and the course of the larger river in the direction of Glaisdale is also hidden behind the steep slopes of Egton High Moor.

Which preposition to use with  esk