WaterMark / Jurisdictions / Pima County, AZ (Tucson)
Pima County, AZ (Tucson): Data Center Water Impact
Reference data for evaluating a data center proposal in Pima County, AZ (Tucson). Every figure below is a stored value with its primary source attached. Facility-scale results are produced by the assessment tool.
Water supply
| Metric | Value | Source / basis |
|---|---|---|
| Water utility | Tucson Water | Utility of record |
| Supply source | Colorado River / Central AZ Project + Aquifer | Utility of record |
| Treatment capacity | 110 MGD | Water stress: WRI Aqueduct 4.0, HUC-8 basin 15050302. Utility data: Tucson Water 2024 Report. |
| Water rate | $7.56 / 1,000 gal | Tucson Water published rate schedule |
| Watershed stress | Extremely High (4.2 / 5) | Water stress: WRI Aqueduct 4.0, HUC-8 basin 15050302. Utility data: Tucson Water 2024 Report. |
Watershed consumptive use
Basin: Rillito (HUC-8 15050302). Figures are consumptive use, not withdrawal, because evaporative data center loss is consumptive. USGS data year 2020.
| Category | Consumptive use (MGD) | Share of basin |
|---|---|---|
| Residential | 75 | 21.9% |
| Thermoelectric power | 4 | 1.2% |
| Industrial | 2 | 0.6% |
| Irrigation | 200 | 58.4% |
| Mining | 60 | 17.5% |
| Existing data centers | 1.5 | 0.4% |
| Total | 342.5 | 100.0% |
Total is the sum of the categories listed above. Shares are each category divided by that total. Source: USGS Water Use 2020, Pima County. Mining: ADWR mining sector reports.
Grid generation water (Scope 2)
Generating the electricity a data center consumes evaporates water at the power plant. That volume is real, it is attributable, and it is excluded from most corporate "water positive" accounting. On a thermal grid it is frequently comparable to the facility's own cooling water.
| Metric | Value | Source / basis |
|---|---|---|
| Grid region | WECC Southwest | WECC |
| Electric utility | TEP | Utility of record |
| Grid water intensity | 0.37 gal / kWh | Macknick et al. 2012 consumption factors, weighted by AZ generation mix (EIA) |
| Local peak demand | 2,200 MW | WECC |
| Modeled rate impact | 8% to 18% | See methodology |
Where this water is consumed: WECC Southwest grid plants serving Pima County (incl. Palo Verde nuclear) are located outside the Rillito basin. Scope 2 water is consumed in those source basins.
Run this county at your facility size. The assessment tool computes direct (Scope 1) and indirect (Scope 2) water for a specific load, cooling system, and mitigation stack, with the same citations attached.
Reducing the footprint here
A high stress reading is a design constraint, not a verdict. Closed-loop and dry or hybrid cooling, adiabatic assist, immersion, and reclaimed or non-potable sourcing each move the direct number, and siting against a cleaner grid mix moves the indirect number. The solutions catalog lists each option with its water reduction, its energy and cost tradeoff, and its source.
Regulatory and siting status
Tucson. Extreme stress (Aqueduct 4.2/5). CAP-dependent. On 5 Aug 2026 the City Council adopted Tucson's first large-scale data center regulations 6-1: by-right zoning eliminated, mandatory demonstration of adequate water and power supply, and no potable water for cooling for facilities outside the city's Large Quantity Water Users Ordinance. Applies to facilities over 25,000 sq ft or 20 MW. Separately, the County Board of Supervisors voted 3-2 on 11 Aug 2026 to direct staff to draft a 120-day moratorium on data centers in unincorporated Pima County; the moratorium text has not yet returned to the Board for adoption, so no county moratorium is in force.
- Arid / water stressed
Sources: Water: Tucson Water + ADWR. Grid: WECC SW (TEP). Ordinance: City of Tucson PDSD, 6 Aug 2026. County moratorium direction: AZPM, 13 Aug 2026; Pima County Board of Supervisors File ID 20637.
Comparative siting scores for this county, alongside every other county tracked, are on the US Siting Matrix.
Related counties
| County | Water source | Watershed stress |
|---|---|---|
| Chandler, AZ | Salt River Project / CAP / Reclaimed | High (3.9/5) |
| Mesa, AZ (Maricopa County) | Salt River Project / CAP (Colorado River) + groundwater | High (3.8/5) |
| Pinal County, AZ (Casa Grande / Eloy) | Groundwater + Central Arizona Project (Colorado River) — Pinal AMA | Extremely High (4.6/5) |
| Clark County, NV (Las Vegas) | Lake Mead / Colorado River | Extremely High (4.5/5) |
| Washoe County, NV (Reno) | Truckee River + Donner Lake | High (3.2/5) |
How these numbers are derived
Assumptions, formulas, and the full source list are in the methodology. WaterMark is published by Standard Water Corp and is not affiliated with any data center developer, utility, or government agency.