Ditto what Mr. RedHawk has said: the first order of business will be sculpting your land to maximize water capture and retention. The guiding principle is "improve your land in order of greatest permanence." A well-designed swale will still be positively benefiting your land 500 years from now, long after the
apple trees have passed away and the barn has outlived its usefulness. Determining your keyline and marking out where your swales will go will determine everything else on the property. Its easy to imagine where you'll site the future house, for instance, or where you might plant a garden and orchard. But earthworks need to take first priority. Once those are established, then roads, buildings, and finally plants and animals will follow.
The first principle of
permaculture is observe and interact. To do so, you've got to lace up your walking shoes and get out there on the land as much as possible. Walk the property and make sure you are doing it throughout the year as the seasons change. Get to know it intimately. Dig down and get a sense for the soil around the entire property. What natural features are not evident at first glance? How does the sun move across the land? Wind? Water? What are the unique microclimates? How do animals move across the land? Where are the natural "edges" (as you'll want to maximize the edge effect).
If that were my land, I'd love to see beavers take possession of that creek/spring and do the hard work of water retention for me. Any chance you could either lure or relocate a family of beavers to build water capturing dams for you?
Here are some links about reintroducing beavers in Montana:
https://blog.nature.org/science/2016/05/20/beaver-dam-nature-conservancy-is-restoring-streams-water-freshwater/
ftp://mymontanalibrary.org/Maxell/Beaver/Beaver%20Report%20-%20TU%202009.pdf
https://onlinelibrary.wiley.com/doi/abs/10.1111/rec.12105
http://www.martinezbeavers.org/wordpress/wp-content/uploads/2013/10/Beaver-Restoration-Toolbox-Karl-Malcolm-2013.pdf
Youtube beaver restoration. There are some cool videos out there. Here is one on using beavers to restore sage brush ecosystems.
https://www.youtube.com/watch?v=8ehvvGcwwmU
Here is another that seems relevant to your situation.
https://www.youtube.com/watch?v=2_cml_cXPmE
First steps right now:
1. Begin planting willows, bullrushes, cat tails and other beaver eatables. Establishing the right food sources will be critical to keep beavers on your land once they are introduced. Willows, in particular, are easy to plant (you just jab a fresh willow branch into the muddy ground and it will take off on its own). You could plant hundreds of them along that watercourse and they will quickly established. Other trees common to your area that provide good beaver forage include aspen, birch, aquatic plants, ferns and grasses.
2. Consider building what they call "Beaver Dam Analogs". Google it. They are easy
enough to create. These will also serve as a check dam to capture erosion and build up sediment in the creek bottom. Once beaver are re-introduced, they'll quickly take over the work of maintaining these BDA's, turning them into their own dams.
Here is a great webinar on how to do it:
https://www.youtube.com/watch?v=GGRJ-ct8AzQ
DREAM BIG! Why can't you restore beavers to your land? They probably once existed there and were responsible for much of the landscaping that occurred there over the centuries. If you were able to re-establish beavers, it would raise the water table and transform the entire watershed. It would be amazing.