Updated August 2026
Deepest Lake in Arizona: Roosevelt Lake
Roosevelt Lake is Arizona's deepest lake, per the Salt River Project (SRP) — operator of Theodore Roosevelt Dam. Lake Powell is the deepest water touching Arizona and its deepest point — 583 ft at Glen Canyon Dam near Page, AZ (USACE NID hydraulic height for Glen Canyon Dam) — is physically in Arizona, but the reservoir is shared with Utah and most of it lies in Utah. Lake Mead (532 ft max depth per NPS) is likewise deeper but shared with Nevada, with its deepest point at Hoover Dam on the state line. Published depths for Roosevelt Lake differ between sources; the agency's figure is 188 ft, so no single number is settled. No Arizona lake has a surveyed maximum depth on record.
Bathymetric surveys are published state by state, so measured depths exist for some states and not others. Browse all Arizona lakes for the water-quality data that does exist, or open Roosevelt Lake's lake page.
Sources and method
- Deepest lake: Roosevelt Lake, per the Salt River Project (SRP) — operator of Theodore Roosevelt Dam, 2026-07-30. The agency's figure is 188 ft; other published depths differ, so no single number is treated as settled. Roosevelt Lake lake page
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Frequently Asked Questions
What is the deepest lake in Arizona?
Roosevelt Lake, in Gila and Maricopa County. Lake Powell is the deepest water touching Arizona and its deepest point — 583 ft at Glen Canyon Dam near Page, AZ (USACE NID hydraulic height for Glen Canyon Dam) — is physically in Arizona, but the reservoir is shared with Utah and most of it lies in Utah. Lake Mead (532 ft max depth per NPS) is likewise deeper but shared with Nevada, with its deepest point at Hoover Dam on the state line. Published depths differ between sources; the agency's figure is 188 ft, so no single number is settled. Source: Salt River Project (SRP) — operator of Theodore Roosevelt Dam, 2026-07-30.
How are lake depths measured?
Maximum depth is the deepest point at full-pool water level, from state agency bathymetric surveys and, for reservoirs, dam-design records. The ranking uses surveyed depths only, never modeled estimates. Everyday water level can sit below the surveyed figure during drawdowns or drought. Mean depth, the average across the whole basin, is listed where a survey recorded it.
Why are some Arizona lakes so much deeper than others?
Lake depth depends on how the lake formed. Glacial lakes (common in MN, WI, MI, NY) were carved by ice sheets and can exceed 200 ft. Reservoir lakes (common in IA, MO, OK, KS) are shaped by river valley depth at the dam site — typically 50-150 ft at the dam, much shallower upstream. Flooded mine pits can be deeper still. Oxbow lakes and pothole lakes formed by river meandering or glacial pitting tend to be shallower, usually under 30 ft.
Does deeper mean cleaner?
Not directly, but deeper lakes tend to be cleaner on average. Depth creates thermal stratification in summer, isolating cold deep water from surface algal blooms. Deep lakes also resist nutrient resuspension from wind-driven sediment mixing. That said, many deep lakes still suffer from impairment if the watershed loads heavy phosphorus — each lake's page carries its nutrient readings and EPA impairment status.