I found several beige water bugs that look like little pills about 5 mm big in a puddle. What are they?

Question

A water pipe had been accidentally left on at the local park, creating several large puddles about 3-6 inches deep. They all had aquatic insects in them. Most had ones I could easily identify like mosquito larvae, water skippers, or boatmen. One had what looked like millions of these little pill-shaped bugs. They were obviously swimming quickly around leaves that had fallen into the puddle. They look like small little balls. I couldn't make out any arms, legs. or heads. I was afraid to touch them for fear they might bite or carry disease. Anybody have any idea what they are? I live in Sacramento, California, USA.

Answer 1

I am not sure but these might help -

http://www.einsteins-emporium.com/life/a...

http://www.whatsthatbug.com/

http://www.insectimages.org/

Answer 2

maybe sperm.