Pat's Big Ol' Mud Page:
How to Fix A Muddy Run
When chicken spend a bunch of time in one area, a common consequence is bare dirt, which in wet weather becomes mud. If you confine your chickens to a run, you are quite likely to have a mud problem eventually, unless you live in the desert or on extremely free-draining soil. Even if your chickens roam loose, you can still wind up with a mud problem right around the coop, or in favored areas such as under the bush where it's nice and shady in summertime. The problem is that chickens devegetate the area (thus, no roots to knit the soil together, also no greenery to draw up water to dry the soil) and by several mechanisms tend to slightly lower the soil level in the area, creating a sort of 'bathtub' that catches and holds whatever moisture comes its way.
Mud is not good for chickens. It can promote bumblefoot and internal parasites, as well as making it less easy and pleasant for chickens to get around. Mud is even worse for chicken owners. A muddy run looks awful, gives you brown bedraggled chickens, stinks to high heaven, and breeds a lot more flies than a dry run does.
I have worked with horses, quite a lot and all over the place, for most of forty-some years, and believe me, I have been acquainted with more than my share of mud and mudholes and the fixing thereof. I suggest the following three-part strategy:
Part One: Intercept Water Before It Enters the Run
Mud happens when water gets into the run. So, as much as possible, keep it out.
Build your coop and run on high ground, or move them there if at all possible. I know this sounds stupid, but honestly, if your coop and run are in the lowest place around, or lie in the usual path of snowmelt or thunderstorm runoff, or next to a marshy area, then it can be better to have one aggravation once (relocation) than to battle mud and flood for the rest of your life.
Put gutters and downspouts on all roofs nearby (yes, even a little 4x4 coop can benefit from gutters if you've got a mud problem!), making sure that the downspouts lead the water well away downhill. Nonperforated corrugated black drainage-tile pipe is cheap and makes good long flexible extensions for downspouts.
If possible, block rain from coming through the top or upwind side(s) of your run. In some climates, a tarp over a small wire-topped run may stay put; in others it will collapse with the weight of pooled rain, or blow away taking half your run with it. In a rainy climate it can be worth building a proper raftered roof (engineered to withstand likely snow load). As long as your run fence is strong and mounted on good posts, you can tie a tarp to the upwind side, or lean a piece of plywood there, or even put up shadecloth (which will keep out much of the rain).
Dig a little ditch to intercept water coming from higher ground and lead it away elsewhere.
Dig a little trench or swale around the coop and run; water will drain into it and an extension of the ditch or swale can lead the water away to lower ground. If you are stuck with a coop in the lowest part of the landscape and cannot move the coop, you can try digging a large deep hole (like 3x3x3, or more, I really do mean large and deep); backfill with concrete rubble and gravel to less than a foot of the surface, top with a layer or two of landscape fabric, then cover with soil and sod... this will take care of modest amounts of runoff. When digging a trench or swale around the run, I suggest staying 2' or so from the bottom of the fence, as you do not want to weaken the set of the fenceposts nor invite digging creatures to try their luck. Usually you don't need much depth of trench to get valuable drainage, so I'd suggest starting small and you can always enlarge it later. If you are worried about looks, peel back the turf before digging the shallow trench, then replace it; soon it will knit back together for a nice clean-looking grassy swale.
Part Two: Temporary "First Aid" for Muddy Footing
If your run is a mudpit right now (which it probably is, if you're even reading this :P), then I would suggest thinking in terms of a temporary 'band-aid' type fix til you get to a drier season, at which point you can apply a more permanent cure (sand or gravel). Reason being, sand or gravel have a very strong tendency to disappear without a trace (usually within weeks or months) if put into active mud.
You're looking for something cheap to raise the chickens up above tide level, so to speak. Because cheap materials are generally organic materials they will also to some degree or another absorb moisture and provide greater surface area to evaporate the moisture to the air; but their main role is to just get the chickens up out of the mud. So add a good big whack of whatever you can readily get. The more you add, the more effective it will be and the longer it'll be effective. Don't bother just putting a little bit in -- it will merge with the mud and merely make the mud worse.
Coarse stuff is better than finer stuff, because it will decompose more slowly and therefore last longer. Coarse bark or woodchips are really good and can last a fairly long time; medium-size wood chippings or finer types of hogfuel are okay; straw and hay and shavings are at least temporarily better than nothing but usually start breaking down pretty quickly. The problem with stuff starting to decompose isn't just that it loses its useful structure -- it will almost always make your mud problem worse in the long run, by providing fine humusy material that makes the soil extra spongy and water-retentive. Good for the garden; bad for the chicken run.
Therefore, it is really useful to keep an eye on the situation and rake your organic material out (replace with fresh stuff if necessary). At the very least, I suggest raking/shovelling it all out in the dry season (or for those in the Pacific Northwest, "less wet season"). By then it will makes excellent mulch or garden soil amendment by that point, and removing it from the run means your permanent fix (see below) won't have as big a problem TO fix.
Part Three: Permanent(ish) Fix For Muddy Footing
So now it's the dry season. Mud? What mud? THIS is the time to create a better all-weather surface for the run.
If you've just got mud right around the coop, where the chickens come out of the pophol, a fairly cheap and easy solution is to lay down big concrete pavers, ideally atop a couple inches of levelled gravel, or even just a couple of cinderblocks if it's just a small area where they hop out the door.
For larger-scale problems, if your soil is basically fairly free draining and you don't have serious mud problems, it may be reasonably sufficient to build the run footing up a bit higher. Add retaining boards at the foot of the run fence (I'd suggest pressure treated ;umber or a naturally rot-resistant wood such as cedar, redwood, black locust; or it is possible to use cement blocks, pavers, etc if they are tied in place well enough) and just add however much soil it takes to put the run decidedly higher than the surrounding soil.
When you put in your retaining boards (or whatever does the job for you), make very sure there is some drainage available through them, either in the form of little gaps between boards or 1/2" drainage holes drilled at frequent intervals. Sometimes it is useful to put small patches of landscape fabric or little wadded-up pieces of scrap windowscreen in front of, or in, those gaps or holes in order to prevent water from rushing out so fast it erodes the run footing. You may have to see what happens and adjust accordingly. If you do not have sufficient drainage openings, your run will become a temporary aboveground pool, which is not what you want, or water can build up high enough that when it DOES rush out it takes a lot of your run footing with it.
However, lot of us (and I currently live in a low floody spot on clay, so this definitely includes me!) need a bit more help to prevent re-muddification of the run. Sand and gravel are your friends, either individually or mixed together, or even in the form of the sand-gravel-dirt mix typically sold as "roadbase" or "A gravel" or other local names. You may be able to avoid middleman markup by contacting an aggregates company (in Yellow Pages under "aggregates", in many areas) that does retail business and seeing if they'll deliver directly to you. Otherwise you may have to get it from a landscaping contractor or large garden center. The place nearest you may be cheapest because per-mile delivery charges add up, but it's still worth calling around. They'll dump it in your driveway or wherever you want that their truck can get to; wheelbarrowing it to the run is plenty of good exercise :) For very very small runs you can also buy bagged sand or gravel, but they are vastly more expensive on a per-volume basis.
I'm not sure it's ever worth putting down less than 3" or so of sand or gravel; a run that gets really seriously boggy or submerged may take 6-8" or more. Remember it will settle somewhat over time. You will need to top it up eventually to replace losses, but for most people it will be a number of years before this is needed, if you put enough down in the first place.
Remember, though, put it on DRY ground, preferably as bone dry as your area gets, or you are almost certainly wasting your money and time.
Yes, chickens can still scratch and dustbathe in sand or gravel or roadbase runs. There probably wasn't much edible growing in your dirt/mud run anyhow, so not much change in that regard, but I like to chuck all my garden weedings (toxic plants removed) and veg garden surplus and odd bits of sod cut out when enlarging beds, and hay sweepings from the horse hay, and seed-head-bearing mature grasses that I weedwhack from our drainage ditches, and so forth... that gives the chickens plenty of entertainment, and can be removed to the compost pile when the chickens have gotten all the entertainment value out of it.
What to Do When Your Coop Floods
Occasionally, even if your coop and run are normally high and dry, circumstances will conspire to flood your coop.
If the floor is just damp and not likely to get any worse (like very minor flooding from a storm or snowmelt, or if your auto watering system exploded), just change out the bedding (preferably with something very absorbant like good marketed-for-bedding pine shavings, even if you normally use straw or pine straw or other alternatives) and maximize your ventilation, perhaps with a fan added if possible, and things should be fine pretty soon. The bedding that you removed, if still fairly clean, can be spread on a hard surface (driveway, tarp, patio slab, whatever), in the sun but out of excessive wind, for a few days, and stirred occasionally, and once it is thoroughly dry it can be returned to the coop for reuse, providing the coop is good and dry by now too. It may take a couple changes of shavings to dry the coop; once you've got it mostly dried out, it can be useful to leave it unbedded for a day or two to let the floor and lower walls finish drying. Again, maximum ventilation is your friend and if it's possible to point a fan at the wet bits too (without chilling or annoying chickens, or doing electrically-dangerous things) then that will considerably speed the process.You want to get it thoroughly dry as quickly as possible, to prevent rot setting in at hidden points in structural members.
Sometimes, though, the coop becomes a virtual aquarium. Usually this involves circumstances you can't do anything about, like a giant storm dumping buckets of rain. If you keep some pallets on hand, you can put them on the floor of the coop, several layers thick if necessary, so chickens can stay above the water; if you happen to have some plywood or old carpeting around you can put that on top of the pallets to create a real 'floor'.
Be very careful about electricity if your coop gets to this point. I would strongly, strongly suggest cutting the breaker in the house that serves the circuit the coop wiring is on, if there is any possibility that standing or flowing water may have gotten to the level of junction boxes, outlets, switches, ends of extension cords, etc etc.
Once the tide has gone back out, you can shovel out all the soaked bedding (warning: exceedingly heavy), which is probably not worth trying to save, and replace with fresh absorbant bedding, and use the procedure described int he previous paragraph, lather rinse repeat as needed, til the coop is dry again.
Chances are, though, you will be "blessed" with only a normal run-of-the-mill muddy chicken run, and I think you will find that the measures described above will make a big improvement and maybe even solve the problem entirely. Now if only they worked on an entire property, then my life would be perfect... ;)
Good luck, have fun,