What are the needed ground conditions for swale construction? (how dry?)

How dry should the soil be before considering doing earthworks like swales? Does regular spring rains rule out being able to do swale construction until the heat of the summer? I don't want to wait, but have been persuaded that the ground must be dry.

THANKS!~

Are you using heavy equipment? I don't think ground moisture level is terribly important to constructing swales by hand (shoveling mud, no, but waiting for dry? unnecessary).

With equipment, tearing up the ground in general and compaction are worse with ground that is too wet, and too wet for a multi-ton excavator is much drier than too wet to shovel by hand.

I am using a Kubota back hoe. I should have mentioned that.

I went ahead and dug the swales. It was only about a week of drying weather after a wet mushy winter. The swales with less catchment, were much easier to dig. There was minimum ground damage (besides some compaction). The only real issue I had is the swale berm is much harder to to shape when the ground is wet and clumpy. After a few days of the berm drying out, I came back, and shaping it was much easier. Thanks for the response!!

Take care,
Michael