Aasgar surprises Kurst with his animal husbandry skill, getting admiration from the patrol captain. Likewise, Gharmez does well with soundings. In fact, with her on soundings Abenor had gone to take her place on the bench and one of the captain's own half-orcs is in the crow's nest.

The boat spent about a third of the day enjoying the downriver movement as before on the Kestrel River. But then it joins the River Esk, which continues southeast 15 miles or so to Vigil, the capital of Lastwall. But where you have to go is upriver. So Aasgar is even there when the horses are unloaded and men are taken off the bench for the most part (only a couple to use oars more for guiding, as the oarsmen just can't fight against the current like the horses) to guide horses.

Gharmez spotted an obstacle in the river even before the half-orc in the crow's nest, once you've gone several miles up the River Esk, as the keelboat’s draft horses slowly pull the boat upstream. Ahead, a crude dam constructed of large boulders, animal carcasses, and mud blocks the keelboat’s route upriver.

The captain confides in you that technically, you are still in Lastwall, and there's no way orcs would put up such a barricade because they enjoy shipments by river as well. It is too big a dam on too wide a river to be put up by an animal, so "something or someone else" is doing this. And he asks the PCs to go up and do a safety check. Even if it turns out no hostiles, it is going to take as much as three days for everyone on the crew and the horses to dismantle enough of that dam for the boat to get through safely.