Full pool is a design line, not a flood line
Every reservoir is run against a set of elevation lines fixed when the dam was built. Full pool — the number every LakeDates page measures from — is the top of the conservation pool: the storage the lake is meant to hold for water supply, hydropower, and recreation. When a lake regular says "the lake is full," this is the line they mean.
Flood pool: the space above full
Flood-control reservoirs keep a band of empty space above full pool. After heavy rain the lake is allowed to rise into that flood pool and is then drawn back down on a schedule. A lake two feet above full pool isn't broken — it's working — but shoreline parks and low ramps can be underwater while it drains.
Dead pool: where gravity gives out
At the bottom of the working range sits dead pool, the level below which water can't reach the outlet works by gravity. Between conservation and dead pool is the inactive pool — water that exists but isn't normally usable. Recreation gives out far above these lines: ramps go dry and marinas move long before a lake approaches dead pool.
So what does "10 feet low" mean?
On every lake page here, "below full" measures from the conservation-pool line, in the datum the operator publishes. Ten feet down on a deep canyon reservoir can leave every ramp usable; ten feet on a broad, shallow lake can move the shoreline a quarter mile. The seasonal band on each page — the lake's own normal range for the date — is the honest way to read the number.
Quick answers
Is full pool the highest a lake can go?
No. Full pool is the top of the conservation pool — the storage the lake is designed to hold for supply and recreation. Most flood-control reservoirs can rise well above it into the flood pool after heavy rain, and that space is meant to be emptied again.
If a lake is above full pool, is something wrong?
Usually it means the reservoir is doing its flood-control job: holding storm inflow in the flood pool and releasing it on a schedule. Parks and low ramps can flood while it drains, so high water deserves the same check-before-you-tow caution as low water.
What is dead pool?
The level below which water can no longer flow through the dam’s outlet works by gravity. A lake approaching dead pool is in serious drought territory — but for recreation, ramps and marinas give out long before the water stops moving.