They are, which let me to wonder whether I'd really grasped the second half. After some more time poring over dictionaries, OTOH, I'm pretty sure my misunderstanding was in l.3-4. Here's a revision of the first half:

The river’s clear, a long thin sash.
My cart-horse walks on idly.
The current seems to share my feelings.
The birds at dusk go home with me.