H009
Is Lake Powell's shoreline longer than the entire West Coast?
A lake in the Utah and Arizona desert is said to have more shoreline than California, Oregon, and Washington combined. Measure the coast one way and it's true. Measure the coast as carefully as the lake and the coast is four times longer.
The comparison uses two different rulers. Lake Powell's 1,960 miles follows the water into dozens of winding side canyons. The West Coast's 1,293 miles traces only the outer coast, cutting straight across San Francisco Bay, Puget Sound, and every other inlet. Measure the coast with the same care as the lake, following every bay, island, and tidal river, and it comes to 7,863 miles: four times the lake.
A comparison is only fair when both numbers were measured the same way. When a statistic sounds astonishing, check whether its two sides used the same ruler.
Try it somewhere else
Two towns compare last winter's snowfall. One measured every hour; the other measured once a day after the snow had settled.
Before calling one town snowier, what would you need to know?
See the numbers
| State | Broad-strokes coastline | Detailed shoreline |
|---|---|---|
| California | 840 mi (1,352 km) | 3,427 mi (5,515 km) |
| Oregon | 296 mi (476 km) | 1,410 mi (2,269 km) |
| Washington | 157 mi (253 km) | 3,026 mi (4,870 km) |
| West Coast total | 1,293 mi (2,081 km) | 7,863 mi (12,654 km) |
| Lake Powell, when full | — | 1,960 mi (3,154 km) |
How was each number measured?
Broad strokes: the “general coastline” comes from a 1975 NOAA study, measured on nautical charts. It follows the outer coast and skips bays and inlets, so Washington, with all of Puget Sound, counts as only 157 miles (253 km).
In detail: the “tidal shoreline” was measured by hand in 1939–40 on the most detailed charts available. It follows the outer coast, offshore islands, bays, sounds, and rivers up to where the tide stops or the water narrows to 100 ft (30 m) wide. With Puget Sound counted, Washington jumps to 3,026 miles (4,870 km), nearly as much as California.
Lake Powell: the U.S. Bureau of Reclamation's 1,960 miles follows the lake's edge into its side canyons, much closer to the detailed method than the broad one.
The lake that number describes isn't there right now
The 1,960 miles describes a full lake, at 3,700 ft (1,128 m) above sea level. In August 2026, Lake Powell fell to a record low of about 3,517 ft (1,072 m), 183 ft (56 m) below full and just 22% full. NASA's satellite images that September showed the lake looking “like a wide river winding through” the desert, with many of its branching canyons drained.
So a figure still repeated in travel guides describes a lake that hasn't existed for years. Some measurements expire: a shoreline, a population, or a price is only true for the moment it was taken.
Why does measuring in more detail always add length?
Any wiggly edge gets longer the more closely you follow it, because each closer look catches bends the last one skipped. Coastline Paradox shows this with a ruler you can shrink: the coastline never changes, but the measured length keeps climbing. Lake Powell is that effect hiding inside a real-world comparison.
Related exhibits
Sources: U.S. Bureau of Reclamation, Glen Canyon Dam: Lake Powell's 1,960 miles of shoreline when full, full pool of 3,700 ft, and 186-mile length; Lake Powell elevation and storage for the end of August 2026 (3,517.87 ft, 22% of live capacity). NOAA, Shoreline Mileage of the United States: tidal shoreline for California, Oregon, and Washington. General coastline: Congressional Research Service, from NOAA, The Coastline of the United States (1975). NASA Earth Observatory, “Lake Powell Drops to Record-Low Levels” (September 2026). Kilometers converted from miles.