The guy and his son arrived a bit after 9 AM. They took the lid off the septic tank (after having to prune several enthusiastic bushes in the vicinity) to pump it out, and to my surprise there was no odor. The son trimmed off bits of intrusive greenery, then ran a snake down the pipe to the road--clearing that of intrusive roots.

The fee was VERY reasonable--the guy called it "senior discount." (Do I really look over 65? My hair has yet to turn gray.)

The guy checked all three commodes to see that they were clear of blockages.

And now all is well in the plumbing department.