The Storm — seed 450

You run the river.

It is spring. You have spent two months refilling three reservoirs for the summer season, and a storm is coming. You do not know how big it is or which valley it will sit over — only a forecast cone that narrows as the storm gets closer.

Do not lose a dam. Overrides everything. If a pool goes over the top, the structure is gone and so is the valley below it.
Keep Franklin Landing under flood stage. The channel takes 55,000 cfs. Damage rises steeply past that.
Finish near summer pool. Dumping the reservoirs to be safe has a cost that lands in June.

Your reservoirs are buffers. Water you cannot store, you must pass downstream — and the town is the bottleneck. Every six hours the question is the same: do I have enough empty space upstream for what is coming? Releasing early is cheap. Releasing late is a flood.

Two units, and the whole job is converting between them. Rivers are measured as a rate — cfs, cubic feet per second, how fast water is moving past a point. Reservoirs are measured as a volume — acre-feet, enough water to cover one acre one foot deep, about 326,000 gallons. The forecast arrives as a rate. The decision is about a volume. The panel under the forecast does that conversion for you.

Drag a release to let water out. Watch the strip: the first few columns will not move, because that water has already left the dam. Advance 6 hours steps the clock; Skip to next decision runs forward until something changes. The ? button top-right brings back the units at any time.

Scenario complete

Played as	Flood damage	Highest stage	Summer pool

Units and terms

cfs: Cubic feet per second — a rate, how fast water moves past a point. A garden hose is about 0.02. This river carries 55,000 before the town takes water.
acre-foot: A volume — enough to cover one acre one foot deep, roughly 326,000 gallons, or about half an Olympic pool. Reservoir space is measured this way. Ridgewater alone holds 700,000 of them.
stage: How high the river is at a gauge, in feet. Not depth exactly — it is height above a fixed reference mark.
flood stage: The stage at which water starts leaving the channel and doing damage. At Franklin Landing that is 32 feet.
pool: How full a reservoir is, as a percentage of its flood pool — the top of the space set aside for catching floods. Past 100% the spillway takes over and you no longer control the release.
spill: Water leaving over the spillway because the pool is too high. It is not a decision; it is what happens when you run out of room.
release: Water you choose to let out through the outlet works, in cfs. Once it leaves the dam you cannot call it back.
travel time: How long water takes to reach the town from each dam — 18 hours from Blackfork, 24 from Ridgewater, 30 from Sable Creek. Release from all three at once and they arrive hours apart.
summer pool: The level the system was refilled to for the recreation season. Finishing well below it has a cost that lands in June.
GWh: Gigawatt-hours — the electricity generated as water passes through the turbines. Roughly what 90,000 homes use in a month.

Every figure here is plausible-looking rather than sourced — this is a test of the mechanic, not a hydrology model.