Western Pondhawks look just like Blue Dashers, except that instead of having a white face, like a Dasher, they have bright green faces.
In fact, female Western Pondhawks are all green as are young males when they first emerge from the pond as fliers (Eastern Pondhawk females have black marks on their green bodies).
Then, while the females stay all green, males slowly develop a blue waxy coating called pruinosity which obscures their original green coloration. If you see one at this stage in his life, he will be blue on the end of his body and green on the front- very pretty:
When mature, this pruinosity will cover all but the green on the face (see 1st photo).