At first I thought red-chested sunbird: back is iridescent green and blue and rump is blue (at least appears to be on some pictures), red (not purple) breast band, no yellow sides to the red breast band, female (last picture) has spotted not streaked chest. Habitat (lake shore) fits as well. Tail feathers and location do not quite match though.
Best other guesses would be 1) Shelley's, but female's breast pattern does not fit and 2) purple-banded but breast band seems to be pure red not purple...