Lake Granbury Flood Ops Frequently Asked Questions Worried about the low lake level at Lake Granbury? Don’t worry. BRA hydrologists normally pull down the lake level at Lake Granbury when a large release is being made from Possum Kingdom Lake and flowing downstream toward Lake Granbury. Lake Granbury will refill and will be full when the rain events end and flood gates are closed. Worried about debris in the lake? Good, you should be worried here. It’s normal for debris to be swept downstream during large rain events and it’s been raining for quite a while now. If you go out on the lake at this time, you are taking a chance at serious damage to your watercraft and potentially your...