The spring on this property served the previous owners for 35 years, and has been in use nearly a hundred, so it must be fairly reliable. Since it's what I have to work with at the moment, I just need to improve the system sufficiently to keep it operational for the time being.
I spent the entire day working on the water system. The good news is that I found that the poly pipe that leads across the creek had come apart at a fitting on a valve, and required reinstalling. It looked like they had problems with this before, there were two hose clamps on the barb fitting. I cut a new end on the pipe, and installed a piece of narrow aluminum to the outside of the pipe, strapping the pipes on each end of the valve together externally with two additional hose clamps, I doubt that this will be a problem again.
The very good news is that the plumbing on the Housetruck survived the freezing last night. The bad news was that afterwards, I had water, but only about 18 PSI at the house. I decided that a trip to the spring was warranted (again). This time I took along a short shovel and my big heavy digital camera.
At the spring, I again found the collection barrel empty, so I removed the diversion and began running the full output of the spring into the barrel. It took quite a while to fill, so I’m assuming that there is a lot of water being lost somewhere in the plumbing running down the ravine.
While I was waiting for the barrel to fill, I used the shovel to improve the path, working my way back from the spring towards the ATV track. The soil was soft, and in about half an hour, I managed to produce a fairly level foot path where before there were only slight shelves to walk upon. It still needs a lot of work, and it’s not done for the full length, but it’s a lot less scary to travel. That's my sweat shirt hanging from a branch above the path, to put it all in perspective.

Once the barrel was full, I tried removing all of the input from the barrel to watch how fast the level went down to see how much of a leak I’m suffering. Quite a large one, by the rapidity of the loss of water from the barrel.
It was getting pretty late in the day, so I had to give up on my road building efforts and begin the trek down the hill and back to the truck, parked on the road at the base of the ATV track. Here’s a view of the barrel and its supply. The whole thing is cobbled together with scrap metals, old rain gutter pieces, and the rusty old barrel. The green plastic mesh and the window screening were additions of my own, replacing the crumbling metal screen that was doing nothing to cover the open top of the drum. All of this is getting replaced as soon as I can put something better together and find some help carrying it up the mountain.

Back at the house, I now have full pressure again, 45 PSI, and the first few gallons were clean. After my shower this evening, I checked the spin filter and found it clogged with the same old rust particles, so I’m back to where I was a week ago. Whoopee.
I spent a few minutes attempting to follow the poly pipe up the ravine from the road, but only got a few dozen feet in before it disappeared beneath a jumble of rocks and tree trunks from some ancient collapse on the ravine walls. Ultimately, I'll have to follow the pipe all the way up to the spring and find and patch any leaks that are causing the water loss. This is something I'll have to do over the course of several days, it will be a very arduous task indeed.