Frank,
Technically, ROUNDUP PRO or ULTRA share the same active ingredient as RODEO, AQUAMASTER, AQUAPRO, AQUANEAT and other aquatic formulations of glyphosate (ie, the "active ingredient"). However, three BIG differences separate these products.
1) ROUNDUP PRO (and other terrestrial labeled formulations of glyphosate)generally contain 41% active-ingredient (or roughly 3 lbs. of acid glyphosate per gallon of formulated product). The aquatic labeled formulations contain 53.8% active-ingredient (or roughly 4 lbs. of acid glyphosate per gallon). So, the aquatic products contain approximately 25% more active-ingredient than the terrestrial versions.
2) The aquatic formulations DO NOT contain a surfactant (surface-active-agent, aka a wetting agent), while the terrestrial versions generally DO have some type and amount of surfactant within their formulation. In simple terms, the void left by witholding the surfactant from aquatic formulations allows for more active-ingredient to be concentrated into the bottled product. However, it IS necessary to ADD a nonionic surfactant to the aquatic formulations. BUT, don't use the "cheapest" commercial surfactant because it probably isn't much more than isopropyl alcohol and some fatty acids (both are very cheap components). If the surfactant smells heavy of rubbing alcohol, keep looking. Also, don't use "dish soap" unless NOTHING else is available. Dish soaps contain anionic surfactants and detergents that may be counter-productive to root control effects.
3) Finally, ROUNDUP PRO/ULTRA formulations contains a patented tallow-amine surfactant, which has reportedly caused clouding to the eye-covering of exposed fish.
All those details stated, you are completely safe and labeled to use ROUNDUP PRO down to the water's edge. But, direct applications of terrestrial products to aquatic sites are neither recommended - nor legal. Besides, if you'll calculate the differences between levels of active-ingredients, you'll find that the TRUE cost per pound of active-ingredient isn't as great as it first appears.
There are far too many folks out there making smug comments about "don't say I said this, but...". Stick with a product that is labeled for the site in which it will be utilized - and sleep well at night.
BTW: glyphosate will control cutgrass, although it is difficult to make a positive ID from your linked pictures. Cutgrass normally grows several feet in height around shallow ponds and ditch perimeters. It also lives up to its name!