What concerns me about the entire subject of invasive species - didymo, mud snails, whirling disease, etc. - is that it is presumed that anglers are the main cause of the spread of these organisms. In reality, on most waterways anglers make up a rather insignificant percentage of the total number of water users. We have swimmers, tubers, kayakers, rafters, water boarders, canoers, and a plethora of pleasure boaters. Each of these water users has a greater potential of transporting invasive species than the angling public. This is not to mention the waterfowl, cormorants, pelicans, ospreys, eagles and other water birds that routinely move from drainage to drainage.
This is not to encourage anglers to be lax in their concern about transporting invasive species from one place to another, but the reality is that we are only a very small part of the problem. In addition, while we do not desire to introduce these pests into more and more places it's like Pandora's Box, we have let them out and it is unlikely that we will be able to completely contain them. Fortunately, God has made the creatures in this creation quite adaptable and althought these things do have an impact on our recreation the sky is not falling and life as we know it will not end because of these things.