Level of the Lake

Today’s water budget · Jordanelle Reservoir

Up or down? Down. Reclamation's daily storage for Jordanelle Reservoir fell 546 acre-feet on Sep 28.

Where the water came from and where it went, at today’s rates. Reclamation publishes the dam’s daily release and storage, so both are measured. The leftover line covers water with no meter (withdrawals, seepage, ungauged creeks) and is inferred from the other lines.

The lines above add up to the storage change: what the lake gained or lost. Inflow is current; release and storage are Reclamation's daily figures for Sep 28, so the leftover also absorbs the gap between the two days.

For comparison, Reclamation put inflow for Sep 28 at 42 cfs, calculated from storage and release.

Where it’s going

The release leg is Reclamation's reported total release through Jordanelle Dam for Sep 28. 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 →

62 cfs62 cfs278 cfsout the dam nowProvo62 cfsProvo River armProvo near Woodland59% fullJordanelle storagein 62 · out 278 cfsProvo River below th…USGS gauge at River Roa…
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 USGS gauge, plus the current flow out through the dam (USGS). Labels are gauge readings in cfs. Line width isn’t to scale. The storage line above shows whether Jordanelle is up or down.

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 operator’s daily storage, compared with the day before. The leftover is what it takes to make the lines add up. It lumps together 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.