This is a male of the species. In two genera of California's Belostomatidae do the females lay their eggs on the backs of the males; Abedus, which occurs in fast flowing streams, and Belostoma, which is found in ponds and lakes. The species level ID of this individual was made based on the shape of the pronotum as described in UC Press's "The Aquatic and Semiaquatic Hemiptera of California".

Big thanks to @karinakilldeer for seeing this individual among the flotsam in the Bear Gulch Reservoir.