|The NSP Power Plant tunnels are located down in the historic Saint Anthony Main area; Action Squad has been sporadically exploring them for the last 5 years or so (we'd explored them before the official formation). We originally called them the “Pillsbury Tunnels,” because we believed that they were part of the old stone flour mill. They have a special place in my heart because they are wonderful old tunnels and we've found new ground to explore each time we've gone into them.
The NSP Tunnels sport antique pipes with their three foot diameters absolutely destroyed by rust, minor waterfalls, raw banded sandstone walls that look like a sunset, small underground bridges, and access to above ground structures. These tunnels were used by the old NSP Power Plant to drain water from the river back into the river basin after it had gone through their turbines. They are laid out with parallel tunnels leading from beneath the plant (which is up on top of the cliff) out to the river basin at the base of the cliff. One perpendicular tunnel runs slightly above these, with a bridge over the former water-bearing shafts.
The riverside ends of the water shafts are generally sealed up with concrete blocks, although one of them has a small metal door that allows entrance to the system. It is occasionally padlocked, although half the time the padlock is not even locked. If it IS locked, and you are a true adventurer, you can go under the wall through the water.
There is always evidence of homeless squatters staying just inside the “front door.” The initial tunnel is wide, with sandstone walls and shallow running water on the floor. Just above head height, there is a mess of rotten old boards crossing from one side to another; just inside the entrance. These form a few platforms, which is where the homeless spread their blankets and hang their plastic bags of possessions. We always move through quickly and never fuck with their stuff; for one thing, that's a shitty thing to do; for another, I'd rather not provoke an assault. Squatters are often very territorial, but if you outnumber them and don't mess with them, you're probably fine. Make it clear that you're just passing through and not after their spot if they confront you.
Deeper into the tunnel, there is a bridge overhead; this is the perpendicular tunnel that runs over the series of parallel tunnels that once ran out to the river. If you continue down past this for the time being, you can continue down the initial tunnel. First you must climb up a dirt embankment on the right, then walk up above the tunnel floor on the loose sandstone ledge, and then balancing along a pipe about 10 feet up off of the ground. This will bring you to an elevated section of the tunnel.
At the end of this is a runoff collection well and a really cool looking vertical shaft that cannot be easily climbed, and a hole in the wall to the right. If you climb into this, you'll find yourself in a short dead end natural sandstone tunnel. At the end of this is a small hole through which you can hear falling water in what must be a nearby tunnel system. The hole is only about 7 inches wide, so we've not gone through it. The well and the dead end sandstone tunnel are all there is to be seen this way.
Once you've backtracked to the place you initially climbed up, climb up the other embankment (on the same side of the tunnel as the first, but going back toward the bridge/entrance). To your left will be a very small and short tunnel (more of a hole, really) in the sandstone with a 90 degree bend in it. The first time we did these tunnels, we missed it completely. Wiggle through this hole, and you'll be in a very cool dead end room with rotted out supports and such everywhere, and a couple of feet of water. If you get to the far ledge, you can carefully make your way to the back of the room, but be advised that it is very easy to get a soaked foot here.
Back outside this room, you can continue back to the bridge. Taking a left will bring you to a dead end with a very low ceiling. Taking a right will bring you into the main part of the tunnel system. Stretch out and enjoy having a straight back while you can; there's a lot of stooping to do ahead, unless you're a dwarf.
The first intersection will be a dry dirt tunnel, with dead ends to the right and to the left. The second is full of water and has a thin ledge that you can take to the right into the subbasement of the plant if you choose. You'll have to weasel your way around the support pillars … and there are easier ways to get where it goes, as we found out after taking this route a couple of times. The floor between the second and third cross tunnels is a couple inches deep in running water. The third cross tunnel has sandstone/dirt sides with water in the middle. Take a right on the left-side embankment and you'll be on your way to the plant.
(If you were to continue straight, there is a small vault-style door blocking the way, and a couple of low-ceilinged tunnels full of dirt; one of them with running water containing crawfish and clams. We used to get into the current NSP power plant from this tunnel, but they've since sealed it off.)
After about 50 feet on the dirt embankment, you have to cross the water on some rotten planks, and then crawl through a hole in a plywood wall into the turbine rooms of the plant. Here's where you'll see some huge rusted out hulks of machinery: I'm not going to try to explain them. Pictures will be posted on here when we manage to get that far in the tunnels without blowing up our camera or running out of batteries/film.
There is a stairwell going up on the far left side of this area, but it is all blocked off. A ladder behind the central turbine, however, is not secured and allows access upward into the basement of the plant. This area is full of the remains of machinery and old electrical gadgets, including an area that apparently once held the breakers for entire Minneapolis city streets (their names are stenciled on the wall). You need to watch your step around here, because there are several places where holes in the floor will drop your ass all the down to the subbasement if you try to rest your weight on them.
Most of the doorways and passages out of this part of the plant are bolted and sealed, but there is one that someone has apparently forced open, which leads to a stairwell upward into the main floor of the Plant, which is not abandoned. The lights are on, and if it is not really late, there might be someone working there. The above ground portion of the plant is built kind of like a hanger; a single large open central space with an arced ceiling, with smaller rooms along one side. If you go up the stairs and out the door from this room, you'll come out right in front of “Tugg's” restaurant on the main street.