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Lake Conditions
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Lake levels

Koolau Reservoir, HI

gauge height
6.24 ft
Condition
Steady
7-day change
-0.09 ft
30-day change
-1.28 ft
1-year change
+0.36 ft

Reading as of 2026-10-12 | the U.S. Geological Survey

Since yesterday
-0.03 ft
7-day change
-0.09 ft
30-day change
-1.28 ft
1-year change
+0.36 ft
Record high
10.79 ft

In brief

Koolau Reservoir's gauge read 6.24 feet on Oct 12, 2026.

Source: U.S. Geological Survey

Gauge height above a local reference point; not elevation above sea level.

Lake level timeline

6.06.46.87.37.7SEP 12SEP 17SEP 22SEP 27OCT 02OCT 07OCT 12HIGH 7.52LOW 6.186.24 ft

Records and averages

Current level6.24 ft
Record high10.79 ft (2026-03-21)
Record low5.87 ft (2022-12-15)
Average of all readings6.12 ft
Data span3 years (1,326 readings)

Level schematic

5.677.008.339.6610.99PUBLISHED HIGH 10.79 ft6.24 ftPUBLISHED LOW 5.87 ft

Nearby lakes

Frequently asked questions

Is Koolau Reservoir full right now?

As of 2026-10-12, Koolau Reservoir sits at 6.24 ft. Over the past 30 days the level has fallen 1.28 ft.

What is the water level at Koolau Reservoir today?

The most recent reading at Koolau Reservoir is 6.24 ft (2026-10-12), sourced from the U.S. Geological Survey. Readings on this page refresh automatically as the agency publishes new data.

What is the highest Koolau Reservoir has ever been?

The highest level for Koolau Reservoir in our records is 10.79 ft on 2026-03-21. The lowest is 5.87 ft on 2022-12-15. Our record covers about 3 years of readings.

Why is Koolau Reservoir changing right now?

Reservoir levels move for four main reasons: rainfall and runoff into the basin, releases through the dam for downstream water supply, power generation or flood control, evaporation during hot months, and seasonal drawdown schedules set by the operating agency. Koolau Reservoir has fallen 1.28 ft over the past 30 days. For the operational reason on any given week, check the U.S. Geological Survey directly.

How much has Koolau Reservoir changed over the past year?

Koolau Reservoir is +0.36 ft compared with this date last year (6.24 ft today). The full-history chart above covers 3 years, with a record high of 10.79 ft and a record low of 5.87 ft.

Download and cite

Quote this reading

Koolau Reservoir's gauge read 6.24 feet on Oct 12, 2026.

From the U.S. Geological Survey, updated daily. The sentence changes with every new reading, so quote it with its date.

Download the full record

koolau-reservoir-hi-water-level-history.csv

1,326 readings, Dec 15, 2022 to Oct 12, 2026. Daily readings. The longest gap since then is 9 days, from Jul 17, 2023. Columns: date, gauge_height_ft. 22 KB.

How to cite

MyWaterLevel, “Koolau Reservoir water level, 2022 to 2026,” data from U.S. Geological Survey, https://mywaterlevel.com/lake/hi/koolau-reservoir/, accessed Oct 13, 2026.

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Source: the U.S. Geological Survey. All Hawaii lake levels. Readings are provisional and may be revised. About our data and methods.