These are V-notch canals, made of cement and carry fast moving water. Not many creatures will try swimming or drinking in it. There are smaller mud canals that carry water from these to the field. Insects, birds, and animals can be found there.

Looks like they could fit through the gaps in the side. I doubt it would take them too long to find that, especially if they knew where the canal was

If you look at the pictures, the canals are not enclosed, it's a roof with large openings between the panels as well as on the side.

Creatures like shade too.