Do you pay for maintenance of stall at boarding facility yourself?

I'm trying to figure out what is reasonable.
JT is boarded at a self care facility, I clean and provide feed. I also pay separate to make sure someone looks after his water (only $25 a month, but still). At first he was in the barn with a little outside run for $175/month. Because of his allergies I moved him outside, where he has a shade, size is about the same as when he was in the barn, but all outside for $100/month.
We has a lot of rain the last few weeks and his stall turned into a mucky, muddy mess, it was awful! Now that it has mostly dried up some of the other boarders have had filler and chat delivered to make sure that next time it rains their horses don't have to deal with the mud. They paid for everything themselves and it ran them about $200.
Is it normal that boarders have to take care of things like that themselves? Can I expect to have the BO take care of things like that or does $100 really only pay for a piece of their property and everything else is my responsibility?
I don't want JT to have to stand in something like that ever again and have started looking at other barns, but maybe it's the same everywhere and I should just have his stall fixed up.

No that should be up to the barn owner. It is their property and you are paying for a safe dry place for your horse to stay. Which is up to them to supply.

I think it depends on what is outlined in the contract. If its their property then yes, they are responsible for the upkeep, but if you really are basically paying rent on that little plot, then I'd say you are responsible.

But, it may have just been something that was discussed between boarders and no one brought the BO into it--we at my barn frequently talk of pitching in to make our round pen a little bigger, without consulting the BO.

I agree it really depends on the situation your in. I boarded at a military facility that we payed full board at but were still required to maintain our own stalls and even pay for the wood on the sides of them. Here I pay like $33 a month at the self care military barn for a stall and paddock but still required to pay for whatever I want done to the stall unless all boarders vote to pay for it out of the barn account.

There are no set ways for things to be done at every horse facility.

The actions of the other boarders make it sound like this is the type of facility where you rent the space and you (with in reason) are expected to provide what your horse needs. Have you asked them or the barn owner?
It is a self care place. So this sounds reasonable.

Do you have a contract? What does it say in your contract?

Contract? What contract? There is no contract.
Our BO is a very nice, older lady with loads of plans to fix up the property. She was going to fix the stalls, the arena, the shade, everything really. Thing is nothing ever happens, so the others gave up and bought their own stall footing, because it got so bad last time.
She keeps telling me she is going to re-organize the outside stall area, so I'm afraid to fix up JT's stall only to have him moved and I'd have to do it again. Rain is forecasted again for the week after next, so if I'm to do it myself it'll have to be this weekend....

You should ALWAYS have a contract in any type of boarding situation. It really saves you from "what if"'s like this. What if she suddenly decided to jack up your board fee to 200 dollars a month? She very well could because there isn't a contact outlining how much you are required to pay, and you would either have to pay it, or find somewhere else to board. Especially if this woman is not the most reliable in terms of meaning what she says, a contract is a really nice concrete way to make sure that everyone is happy.

Here is a a sample of what a boarding contract outlines. You can of course type up your own and tailor it to your needs/the needs of the situation. In general, a good contract will outline any fees that need to be paid and on what schedule, a "hold harmless" agreement (if your horse gets sick, injured, is stolen, or dies while on her property), who is responsible for the upkeep of the horse and the facility (like vaccinations, worming, farrier, or rebuilding a fence) and in an emergency situation what the BO should do (vet/farrier contact information, horse allergies, your contact information and an emergency contact)

http://www.stablewise.com/pdf/boarding_agreement_2.pdf

Not having a contract is on you as much as it is on her.

Since you state the barn owner is always saying they are going to do something and never does it I would think it is pretty safe to assume that things are not going to be moved around in the near future either.

In my world my horse comes first. So if spending some money to make him safe and dry is what needs to happen then I would do it.

Is it worth your horse being uncomfortable to stand on principle. And honestly, what you pay is pretty cheap so spending a little money to make the area your horse is in more comfortable should not cause so much frustration on your part.

And bottom line, if you are that unhappy with this barn owner then find another barn.