We've a creek with a place that holds water all year. Normally doesn't flow much except this time of year.
Will Shubunkin stay in such a place or will the migrate when the creek is flowing.
I would not count on them staying.
I'd say zero chance any kind of fish would stay in one area of a creek except when trapped.
Assuming we're talking US I think it would be a federal crime to put goldfish into a creek since it probably leads to a federally owned water supply. The water in the creek is probably owned by the state. Depends on the state and amount of water. But again, the state would have something to say if the water flows to a state owned water supply. There's two ways to look at this. Big gov shouldn't tell you what to do. Or these water ways have been owned by all of us for a really long time and we have a right to protect our property.
From purely a hobby perspective it would be a big help if you didn't put goldfish into the creek. The state of Maine has outlawed the keeping goldfish and koi within the state because of this problem. Many people consider it a crazy law, and maybe it is. But there certainly seems to be a very widespread belief by many people that it's perfectly OK to release all kinds of stuff into the environment. So by not releasing goldfish into the creek you would be helping to keep goldfish and koi legal in your state, and maybe other states, by not adding to a problem that "we the people" would then be forced to address to protect our resources.
Why on Earth would you want to do that? Please don't,
for the sake of the environment and the poor shubunkins.