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. This is a basin-scale worst-case bound, not a river withdrawal: Lima draws treated water from five off-stream reservoirs (~15 BG) filled from the Auglaize and Ottawa at high flow, so the operating constraint is reservoir drawdown, not instantaneous river depletion.

The screen above is the surface-water constraint. Its groundwater peer — the area well concerns: the hypothetical drawdown cone, the documented construction-dewatering wellfield and the domestic wells it drew down, and a screen of the river record for where that pumped water went — has its own page.

Groundwater — the area well concerns →

The screen above weighs the cooling load's volume. The same load also carries heat: cooling water leaves a plant warm, and Ohio writes a numeric temperature standard the Ottawa River has only 5.4 °C of headroom against at design low flow. The thermal screen reads the modeled campus heat load and the corridor's own reported effluent temperatures against it, framed as CWA §316(a) — 3 of 7 screened dischargers clear the criterion , and 2 permits already report an effluent temperature over it .

Thermal discharge — the river's heat budget →

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]

Binding dilutiongrounded

0.01:1

Lima WWTP → Ottawa River

[verified]

Assimilative screen · 4 of 4 receiving reaches fail the dilution band at design low flow (Shawnee II WWTP chronic 0.04:1, acute 0.00:1 (6.21:1 effluent-credited) · American Bath WWTP chronic 0.01:1, acute 0.01:1 · American II WWTP chronic 0.42:1, acute 0.32:1 · Lima WWTP chronic 0.01:1, acute 0.00:1 (0.17:1 effluent-credited)). The design flow is matched to the criterion type — chronic aquatic-life dilution at the 7Q10, acute at the sharper 1Q10; the effluent-credited ratio counts the permitted effluent already in the reach. A screening band, not a permit determination.

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

BOSC routing via theorized-fm3-shawnee-ii to watch-shawnee-ii-wwtp is THEORIZED (unconfirmed) — excluded from the balance; Shawnee II has no known BOSC routing.

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

Load → cooling → water

275 MW (~250–300 MW) IT load [inference] 4 MGD cooling makeup 4.852 cfs net consumptive

The IT load is inferred from the facility's [verified] air-permit backup capacity (N+1), then carried through the cooling archetype's water math — one derivation, not two headlines. The disclosed MW range widens the consumptive bracket. the load and the grid →

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]

Binding dilutiongrounded

0.01:1

Lima WWTP → Ottawa River

[verified]

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

BOSC routing via theorized-fm3-shawnee-ii to watch-shawnee-ii-wwtp is THEORIZED (unconfirmed) — excluded from the balance; Shawnee II has no known BOSC routing.
BOSC campus consumptive cooling is a derived central estimate (~4.9 cfs; 2.85-4.18 MGD evaporative range) from the air-permit power figure x WUE — not a metered or permitted value.