I get the water primrose also. A light spray of Round Up does a quick job on it if you're looking to kill it. Then you can easily rake it out without breaking it into a hundred pieces (which can each grow!!)

Unfortunalety I get the alligator weed too. An easy way to tell them apart is that the alligator weed makes white flowers and the water primrose makes yellow flowers.

Some days you're the bug, some days you're the windshield.