Today’s water budget · Hartwell Lake

Up or down? Down 0.19 ft over the last 7 days (USGS lake level).

Where the water came from and where it went, at today’s rates. Dam releases and withdrawals have no complete public feed, so they land in the leftover line, which is inferred from the other lines.

River inflowmeasured
+379 af/day
USGS gauges, at current rates
Evaporationmodeled
—
Not estimated: no storage or surveyed-area reading to get today’s surface area from
Everything we can’t meterinferred
—
Needs every row above and the storage change first

=Storage changeinferred
—
Not estimated: no storage or surveyed-area reading to get today’s surface area from

The lines above add up to the storage change: what the lake gained or lost.

Where it’s going

Nothing leaving the lake can be put in numbers right now.

No public gauge measures water leaving through the dam, so releases are counted in the leftover. The withdrawals line is the budget’s leftover: city intakes, ungauged runoff and estimation error. The lines can overlap, so treat the split as approximate.

River flow toward the lake now

Swipe sideways to follow the river to the lake →

SteadyReceding · high water draining downOn the rise · climbing right nowInbound wave · big rise upstreamFlooding · NWS, by river heightNo current readingRising or falling is judged from each gauge’s last 48 hours, scaled to its river. Dot speed follows the flow. NWS flood status comes from river height and outranks direction.

Streamflow at the 2 USGS gauges. Labels are gauge readings in cfs. Line width isn’t to scale.

How this is computed

Inflow converts current streamflow at the gauged tributaries (USGS) to acre-feet per day (1 cfs ≈ 1.9835 af/day). Evaporation uses long-term monthly averages for the region over today’s lake surface. That surface area is TWDB’s daily survey where published, otherwise estimated from storage. With no storage reading, evaporation isn’t estimated. Inches on the lake divides each volume by that same surface area, so an inch takes less water when the lake is low and narrow than when it’s full and wide. Storage change is the lake’s level change (USGS) times that surface area, averaged per day over the last day for a once-a-day feed, otherwise over the last seven days. The leftover is what it takes to make the lines add up. It lumps together dam releases, withdrawals, and ungauged runoff, which can’t be split without data the operator doesn’t publish.

All inputs are provisional. This page is an estimate, not an official accounting.