I finnally figured out why there is dicoloration in some of the pictures.
Alamo lake for example the picture of half the lake was taken in the day time and the other half was at night. if you look by the middle of the lake you will see the lights on the boats(bet they are crappy fisherman).
you have to zoom out and scroll the link above about 7 clicks to the west and one click north for alamo
I'd say the "discoloration" in the overall picture is in lighting or camera settings or even post processing of the photos. The "discoloration" of the water in the lakes is reflections from waves due to either wind or boat traffic. You can see the wave patterns in this enlarged sample from Alamo. 8)