It is certainly worth the effort to acquire this material. Composting it would be best and there shouldn't be any problem if the pile gets turned a couple of times.

It is possible that there may be some sprouting in the mulch bed but if you keep an eye on it and tear out any new vegetation, you should be OK.

We are just so happy that they are cleaning out the creek. It was/is full of garbage, old tires(they pulled out 8 this week in less then 100 yds), cottenwood trees, berry bushes, poison oak and who knows what else. These are not the same people who planted the tamerask, just the county roads dept. They are going through the creek with a convict crew to clean it out. They came through this week with a bull dozer and dug out lots of sand,gravel and dirt. They hauled away truckload after truckload. They gave us 4 big truckloads so we could fix the potholes in our private dirt road. We had complained because we were worried about the danger of flooding as the creek was so clogged up with stuff. Free mulch delivered to my yard is just the iceing on the cake for us. There are 5 families on this little road and we will sleep much better during the rainy season once the creek is cleaned out.
Donna

If the plants were chipped when seeds were not present that would be one less issue of concern. I would still be inclined to accept the mulch but I would probably compost it and turn it a lot for a good long while and not add it to your soil for several months or more so you can watch for sprouting of seeds and for vegetative reproduction in the pile instead of in your land. I am attaching a link from the Nature Conservancy which discusses management of tamarisk. All in all, it sounds like some good things are happening in your neighborhood.

Here is a link that might be useful: Tamarisk/Nature Conservancy

Only one caution--are they throwing the poison ivy/oak into the chipper?

I second the caution about the poison oak/ivy.