I don't think that any legit company can use treated lumber for mulch per EPA regs.

I don't use dyed mulch because I don't know what is in the dye (and I don't like the aesthetics.) HD and other big box stores do have undyed mulch. Another source is to make friends with your local arborist and ask him to drop off a load of chipped branches if the trees he has been trimming aren't diseased. I also have asked to crews clearing utility lines to do the same.

I agree that there are regs for disposing of any treated wood.

CCA treated wood has been off the market and banned for a number of years....since the end of 2003. It is highly unlikely that any mulch you find now will contain treated wood. Any CCA treated wood still hanging around as decks or fencing, etc. is considered hazardous waste and must be disposed of under very strict guidelines.

You are worrying unnecessarily :-)

Compost and mulch are not the same thing although, as you discovered, a thick layer of compost can initially function as mulch. The EPA laws about this are clear and would have to be violated to make mulch from this wood. If you buy finely ground hardwood mulch from a reputable source, it is good for the soil. It should be very dark, almost black. If you need a lot, it's usually cheaper to get a truck to drop a load of it although it's more work for you to get it where it needs to go. Mulch comprised of larger pieces will last longer but the trade is that it takes longer for the decomposition process to be of benefit to the soil. Really large pieces, like bark mulch, can fail to perform the most basic functions which most gardeners expect it to do - suppress weeds, conserve moisture because the larger pieces do not become interlocked in place. This also makes it more likely to wash away in a hard rain.

If you want to visually inspect mulch, please do. Although there is a law, we all know people break laws. I bought some mulch at Maxway this spring that was in a bagged called "professional potting soil." It was nothing but shredded wood and I found bits of plastic, painted pieces, straight edges, etc... all through it. An email sent to the Cowart mulch company of Sugar Hill GA got no response.

This is a description of the methods used to visually inspect mulch by the university of FL as one aspect of a process to determine if CCA mulches were being sold:

The primary purpose of visual inspection of the mulch was to identify if the mulch was: a) colored and, b) to look for evidence that it was made from recycled C&D (construction and demolition) wood. Non-colored mulch would have natural variations in color. When the change in color on a piece of mulch was abrupt or in the case where the color was extremely uniform, then the mulch was identified as artificially colored. Abrupt changes in color occurred when the colorant did not penetrate the crevices of the wood showing distinct areas of the natural wood color in contrast with other areas where the colorant penetrated the mulch. An extremely uniform color is an indication that excessive amounts of colorant were used giving the mulch a "heavily painted" appearance. When in doubt pieces of the mulch were broken open to determine if the color of the outside of the mulch sample was different than the inside, again indicating that the mulch was colored. Evidence that the wood was made from recycled C&D wood was provided by the presence of painted wood, other objects that are associated with recycled wood (e.g. nails, rope, and plastic), and engineered wood (e.g. plywood, particle-board, oriented strand board, and possible excess of smooth surfaces on the wood). Smooth surfaces on the wood chips were documented since engineered wood is characterized by sawn boards which are characterized by a greater proportion of smooth or straight edges.

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