Plant floating on the edge of my dam, therefore unable to state height of plant. Only 2 flowers, one not yet open. Also unable to determine the number of plants, though the leaves were floating to about 3m long and about 1.5 m wide out from the bank.
Yes, the white flower is Ottelia ovalifolia. In the background, there are some leaves of Potamogeton, another water plant. It’s leaves are a lighter green, and slightly differently shaped compared with Ottelia, and it’s flowers are very unshowey. You can check what Potamogeton looks like using images in CNM.