Recently my news feed offered this tech news to me and I read with a big interest because a few months ago I was thinking about the same idea.
Good to see US is making its first steps into this direction, and a note a similar project has already been accomplished in India.
As everything new, it has its pros and cons, here are some of them:
Pros
Effective area usage. I can't think of anything else useful built on top of water canals, can you?
Panels provide shade this reducing water evaporation
The shade also reduces the weed growing and decreases the maintenance costs
Cons
Canals maintenance becomes more complicated
The construction holding the panels costs more than usual
With increased metal prices for the more expensive contstruction it is not certain the economical effect is reasonable.
In high-crime areas the security detail on the PV installations would cost a lot.
Anything else?
Here is the article: https://www.euronews.com/green/2023/07/24/solar-panels-on-water-canals-seem-like-a-no-brainer-so-why-arent-they-widespread
Image sourced from the same article.