About Bonneville Spillway Operator

Bonneville Spillway Operator puts you in charge of dam operations on the Columbia River. Balance hydropower generation, downstream flood risk, fish-passage requirements, and reservoir storage across changing inflow scenarios. Engineering-accurate within a stylized interface.

How to play

Each turn (one day or one week, depending on time-step): observe inflow forecast and reservoir level, choose spillway gate openings and turbine flow. Generate revenue from power, lose points for flood-stage exceedance downstream and missed fish-ladder windows. Ten-year campaign rewards consistent balance.

Frequently asked questions

How the model works — the real formulas

The simulation runs a small set of first-principles equations every tick. Units are kept in the operator's own working system — flow in kcfs (thousands of cubic feet per second), power in MW, pool elevation in ft, time in minutes. Reservoir geometry, turbine count and spillway capacity follow public USACE data for Bonneville (nameplate ≈ 1077 MW, Francis units, flip-lip deflectors). Here is what each meter is actually computing.

Reservoir mass balance

The pool is a bathtub. Net storage change is inflow minus everything leaving:

• netQ = inflow − turbineFlow − spillQ − ladderQ (kcfs)
• ΔStorage = netQ · 1.377 · dt acre-feet, where 1.377 = 1000·60/43560 converts kcfs·minutes to acre-feet.
• Δelevation = ΔStorage / reservoirAcres — a flat-pool approximation (surface area constant with stage).

Hydropower

The powerhouse uses the standard hydraulic-power equation P = ρ·g·Q·H·η, with water density ρ = 1000 kg/m³ and g = 9.81 m/s². Rather than convert units every frame, the code folds the kcfs→m³/s and ft→m conversions plus ρg and the ÷10⁶ (W→MW) into a single constant:

• P(MW) ≈ Q(kcfs) · H(ft) · 0.0846 · η

The 0.0846 is that lumped unit-conversion constant (it represents ρg with the imperial-to-SI and W-to-MW factors baked in). Efficiency η is 0.86 for the baseline Francis units, 0.90 after a Kaplan retrofit. Net head is H = poolElev − tailwater − 0.015·Q (a 0.015 ft/kcfs penstock head-loss term), tailwater rising with total discharge along a linearised rating curve capped at +18 ft. Generation is clipped to the nameplate ceiling, and revenue accrues as genMW · (dt/60) · $42/MWh.

Total dissolved gas (TDG)

Spilled water plunges into the stilling basin and entrains air, driving nitrogen/oxygen supersaturation downstream — the mechanism behind gas-bubble trauma in salmon. The model uses the familiar square-root-of-spill form, floored at 100% saturation:

• TDG_target = 100 + coef · √(spillQ), with spillQ clamped ≥ 0.
• coef = 1.5 with plain gates, dropping to 1.0 once flip-lip deflectors are installed (deflectors skim the jet along the surface instead of plunging it).
• The displayed TDG relaxes toward that target: TDG += (target − TDG)·min(1, 0.12·dt).

Regulatory thresholds mirror the real EPA/ODEQ regime: harm to fish begins above 115% (110% during a DEQ inspection window), monetary penalties accrue above 120%, and 130% is a hard shutdown.

Salmon survival

With a fish ladder installed, passage each tick scales with attraction flow and inverse TDG harm:

• attract = clamp(ladderQ / 3.5, 0, 1.2)
• TDG harm fraction = clamp((TDG − 115) / 10, 0, 1) — zero at 115%, total kill at 125%; a juvenile-bypass system multiplies this harm by 0.2 (a 5× reduction).
• Surviving passage ∝ attract · (1 − harm); mortality ∝ attract · harm. The survival fraction is literally 1 − harm, so every extra point of TDG above 115% converts passing fish into kills.

This is an operations model, not a CFD or fisheries-population model: the pool is treated as a single well-mixed volume, tailwater and TDG use algebraic rating relations rather than routed hydraulics, and salmon are a flow-and-gas response curve rather than individual agents. It is calibrated to give the real tradeoffs — spill for fish attraction versus TDG kill, turbine flow for revenue versus pool drawdown — not certified numbers.

Built by a practicing dam-safety and hydraulics engineer. For the real calculators behind spillway and outlet hydraulics, see the free weir, orifice & open-channel tools at pe-calc.com, or HydroComplete for stormwater design software.

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