Hydrology — water balance

Each scenario screens the Ottawa River's low-flow capacity against the campus's consumptive cooling draw: live flow minus consumptive loss against the 7Q10 design low flow, and the assimilative headroom that remains. Live gauge and permit figures are grounded; scenario draws are labelled assumptions.

A written walk-through of this screen — including the newly document-sourced sanitary figures — is in the water-balance assimilative screen memo.

Bullet · draw vs design low flow At the 7Q10 design low flow, the buildout cooling draw dwarfs the river

scale · cubic feet per second

Consumptive draw · buildout

[inference]

4.85 cfs

Ottawa River 7Q10 design low flow

[verified]

0.2 cfs

The modeled buildout cooling draw (5 cfs) is about 24× the Ottawa River's 7Q10 design low flow (0 cfs) — the drought flow Ohio writes discharge permits at. Live flow today (36 cfs) is far higher, but the screen is written for the dry floor.

baseline

Current municipal loop, no data-center cooling draw.

Cooling model: no cooling-water load

Cooling demand: 0 MGD · consumptive fraction 0 fraction

Consumptive lossmodeled

0cfs

0 MGD x 0 consumptive (scenario baseline)

[inference]

Ottawa River 7Q10grounded

0.2cfs

Ohio EPA NPDES fact sheet 2IG00001 (Lima Refining Co.), Stream Flows table — Ottawa River at Lima, USGS gage 04187100, 1989-2021

[verified]

Ottawa River live flowgrounded

36.3cfs

NWIS 04187100 (Ottawa River at Lima OH)

[verified]

Binding dilutiongrounded

0.01:1

American Bath WWTP → Pike Run

[verified]

Assimilative screen · 3 of 3 receiving reaches fail the dilution band at design low flow (Shawnee II WWTP 0.04:1 · American Bath WWTP 0.01:1 · American II WWTP 0.42:1). A screening band, not a permit determination.

Tier-0 water balance · 5 nodes · modeling caveats:

Shawnee II WWTP: summary states a flow expansion; used the first value (3.0 MGD).
BOSC campus consumptive cooling demand is an unsourced assumption (0 cfs placeholder).
Lima WTP withdrawal rate is not documented; abstraction shown as river-flow context only.

buildout

Data-center campus cooling draw (evaporative_tower) on the municipal supply.

Cooling model: evaporative cooling tower (“open loop”) · WUE 2 L/kWh · 5 cycles of concentration

Cooling demand: 4 MGD · consumptive fraction 1 fraction

Consumptive lossmodeled

4.852cfs

3.92 MGD x 0.8 consumptive (scenario buildout)

[inference]

Ottawa River 7Q10grounded

0.2cfs

Ohio EPA NPDES fact sheet 2IG00001 (Lima Refining Co.), Stream Flows table — Ottawa River at Lima, USGS gage 04187100, 1989-2021

[verified]

Ottawa River live flowgrounded

36.3cfs

NWIS 04187100 (Ottawa River at Lima OH)

[verified]

Binding dilutiongrounded

0.01:1

American Bath WWTP → Pike Run

[verified]

Tier-0 water balance · 5 nodes · modeling caveats:

Shawnee II WWTP: summary states a flow expansion; used the first value (3.0 MGD).
BOSC campus consumptive cooling demand is an unsourced assumption (0 cfs placeholder).
Lima WTP withdrawal rate is not documented; abstraction shown as river-flow context only.