It is native. However, it may upset the local ecological balance to add it to the wetland. Is pickerel rush already there? If not, and you add it, what other plants will it displace and what insects, animals or fish that feed on them will also be displaced? If it is already in the wetland, then what will be the effect of adding more?

Another use for your excess plants would be to donate them to your local Master Gardeners, Horticultural Society or Native Plant society for their members or to sell at their annual sale. That way, your plants will go to other garden ponds instead of into the wild.

Here is a link that might be useful: Pickerel Weed