I was just scanning through some articles on our Erie Canal Facts web page www.eriecanalfacts.wordpress.com
and came across the article on Vegetation removal and SEQR, (that's the court case thing).

https://eriecanalfacts.wordpress.com/2018/03/03/the-dispute-about-vegetation-removal-and-seqr/

If you scroll down to the section about Cottonwood trees, you'll learn a lot about them.  What particularly struck me was the mention of the root systems causing piping, a phenomenon where the roots rot away and leave tube voids in the soil. Of course, this is very dangerous because water will quickly flow through these tubes and cause a dam failure.
Several STCC  members have said that it's never happened before and generally scoffed at the idea. And of course, they would probably be correct, because there are no reported incidents on the Erie Canal where this has happened.

I was discussing this with a neighbor yesterday, and I mentioned to him that the Oxbow trail and the Oxbow Embankment Dam were devoid of trees in the 1930s, where there is photographic evidence to prove this. Here we are some 80-90 years later and we have hundreds of Cottonwoods, some 150 feet tall, coming to the end of their life cycle. That means those roots are still alive and still growing.
When these trees die, the roots will still be there for quite a few years, even though Cottonwoods rot easily and quickly, so we won't have experienced a failure due to this, it's too early in their life cycle.

If nothing is done about it, the piping problem will very commonplace, the canal could leak like a sieve. Embankment failure will be commonplace, it just a matter of 'when' not 'if'.

Cottonwood trees!  They grow everywhere and especially on the canal shorelines. They like the water and naturally grow in floodplains. Consequently, their growth is especially rapid on an earthen embankment dam like those between Bushnell's Basin and Fairport, because of the continual and natural seepage of water through the embankment.

Here are some more facts about these trees.

The cottonwood tree is one that is genetically programmed to produce shallow roots because it grows naturally in flood plains.  They grow rapidly if irrigated sufficiently and because they are native.

Lateral roots radiate out, particularly just below the ground-line. Most of the root biomass is between 3 and 12 inches deep, although a few small roots extended to the 4-foot depth.

Cottonwood trees are the fastest growing trees in North America. A young tree can add 6 feet (2 m.) or more in height each year. This rapid growth leads to weak wood that is easily damaged. The trees can grow to well over 100 feet tall (30 m.), with eastern species sometimes reaching 190 feet (59 m.). The canopy of a mature tree spreads about 75 feet wide (23 m.), and the diameter of the trunk averages about 6 feet (2 m.) at maturity. Each cubic foot of tree weighs about 50lbs, so an incredible amount of weight is added to these steep and badly designed slopes.

A 100 feet tall Cottonwood can weigh 140,000 lbs or about 65 tons. Imagine this crashing down these steep embankment slopes.

In the past four years (the time the NYPA's program to clear the embankments of trees has been on hold) those trees have likely grown about 20 feet taller.
These messy trees have weak wood and are prone to disease. In addition, their massive size makes them out of scale for all but the largest landscapes.

Read more at Gardening Know How: Planting Cottonwood Trees: Cottonwood Tree Uses In The Landscape https://www.gardeningknowhow.com/ornamental/trees/cottonwood/cottonwood-tree-in-landscapes.htm

Do cottonwood trees fall over easily? That's the thing about cottonwoods. They grow big and they grow wide, and they get heavy branches at odd angles that are prone to break and fall

Cottonwood trees aren't worth much on the timber market, they can crowd out and shade new conifer plantations, and they don't have many BTUs of energy for firewood use. Their major use has fallen out of favor over the past 100 years = dug-out canoes!

Cottonwoods need a location with full sun and lots of moisture. They grow particularly well along lakes and rivers as well as in marshy areas. The trees prefer sandy or silty soil, but will tolerate most anything but heavy clay. They are hardy in USDA plant hardiness zones 2 through 9.