Country: USA
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Upper Helemano Reservoir water level history

Daily records since 2011 · Level today: 42.23 ft

Highest on record
46.22 ft
Jan 28, 2013
Lowest on record
25.19 ft
Sep 26, 2013
Today
42.23 ft
Oct 23, 2026
Years of data
15
since 2011

In short

Across 13 complete years, 2012 had the lowest average level (35.78 ft) and 2018 the highest (44.23 ft).

On average the lake is lowest in September (37.17 ft) and highest in May (42.70 ft).

Upper Helemano Reservoir level, all years

Loading chart…

Measured Normal range for the date (middle 50% of past years)

Each year's lowest and highest level

24303642472011201320152017201920212023202520262011: lowest 39.83 ft (2011-10-16), highest 46.08 ft (2011-12-14), average 42.23 ft, 151 days measured2012: lowest 30.65 ft (2012-08-15), highest 46.04 ft (2012-03-03), average 35.78 ft, 365 days measured2013: lowest 25.19 ft (2013-09-26), highest 46.22 ft (2013-01-28), average 40.23 ft, 363 days measured2014: lowest 29.27 ft (2014-09-25), highest 45.67 ft (2014-03-30), average 41.80 ft, 363 days measured2015: lowest 29.62 ft (2015-03-04), highest 46.02 ft (2015-11-27), average 41.50 ft, 365 days measured2016: lowest 29.65 ft (2016-03-13), highest 45.89 ft (2016-12-02), average 41.28 ft, 361 days measured2017: lowest 29.79 ft (2017-09-29), highest 45.68 ft (2017-11-29), average 39.80 ft, 333 days measured2018: lowest 37.07 ft (2018-01-19), highest 46.05 ft (2018-03-01), average 44.23 ft, 348 days measured2019: lowest 36.11 ft (2019-07-20), highest 45.57 ft (2019-12-26), average 40.82 ft, 360 days measured2020: lowest 35.69 ft (2020-08-31), highest 45.96 ft (2020-01-12), average 40.63 ft, 365 days measured2021: lowest 35.78 ft (2021-06-08), highest 45.81 ft (2021-03-09), average 40.35 ft, 365 days measured2022: lowest 35.88 ft (2022-06-16), highest 44.57 ft (2022-12-21), average 37.83 ft, 365 days measured2023: lowest 35.88 ft (2023-08-18), highest 45.54 ft (2023-02-21), average 39.92 ft, 364 days measured2024: lowest 35.78 ft (2024-09-28), highest 45.67 ft (2024-05-17), average 40.79 ft, 364 days measured2025: lowest 33.25 ft (2025-12-13), highest 43.53 ft (2025-06-03), average 38.06 ft, 307 days measured2026: lowest 34.69 ft (2026-07-20), highest 46.16 ft (2026-03-20), average 42.03 ft, 287 days measured
2430364247201120152019202320262011: lowest 39.83 ft (2011-10-16), highest 46.08 ft (2011-12-14), average 42.23 ft, 151 days measured2012: lowest 30.65 ft (2012-08-15), highest 46.04 ft (2012-03-03), average 35.78 ft, 365 days measured2013: lowest 25.19 ft (2013-09-26), highest 46.22 ft (2013-01-28), average 40.23 ft, 363 days measured2014: lowest 29.27 ft (2014-09-25), highest 45.67 ft (2014-03-30), average 41.80 ft, 363 days measured2015: lowest 29.62 ft (2015-03-04), highest 46.02 ft (2015-11-27), average 41.50 ft, 365 days measured2016: lowest 29.65 ft (2016-03-13), highest 45.89 ft (2016-12-02), average 41.28 ft, 361 days measured2017: lowest 29.79 ft (2017-09-29), highest 45.68 ft (2017-11-29), average 39.80 ft, 333 days measured2018: lowest 37.07 ft (2018-01-19), highest 46.05 ft (2018-03-01), average 44.23 ft, 348 days measured2019: lowest 36.11 ft (2019-07-20), highest 45.57 ft (2019-12-26), average 40.82 ft, 360 days measured2020: lowest 35.69 ft (2020-08-31), highest 45.96 ft (2020-01-12), average 40.63 ft, 365 days measured2021: lowest 35.78 ft (2021-06-08), highest 45.81 ft (2021-03-09), average 40.35 ft, 365 days measured2022: lowest 35.88 ft (2022-06-16), highest 44.57 ft (2022-12-21), average 37.83 ft, 365 days measured2023: lowest 35.88 ft (2023-08-18), highest 45.54 ft (2023-02-21), average 39.92 ft, 364 days measured2024: lowest 35.78 ft (2024-09-28), highest 45.67 ft (2024-05-17), average 40.79 ft, 364 days measured2025: lowest 33.25 ft (2025-12-13), highest 43.53 ft (2025-06-03), average 38.06 ft, 307 days measured2026: lowest 34.69 ft (2026-07-20), highest 46.16 ft (2026-03-20), average 42.03 ft, 287 days measured
Lowest to highest that yearYear average2026 so far

One bar per year from the lowest to the highest daily level, with the year's average. Years with no bar have no daily record in the agency archive.

Lowest years

Years ranked by their lowest daily level.

  • 201325.19 ft on Sep 26
  • 201429.27 ft on Sep 25
  • 201529.62 ft on Mar 4
  • 201629.65 ft on Mar 13
  • 201729.79 ft on Sep 29

Yearly highs and lows

YearAverageLowLow dateHighHigh date
2026 (287 days)42.0334.69Jul 2046.16Mar 20
2025 (307 days)38.0633.25Dec 1343.53Jun 3
202440.7935.78Sep 2845.67May 17
202339.9235.88Aug 1845.54Feb 21
202237.8335.88Jun 1644.57Dec 21
202140.3535.78Jun 845.81Mar 9
202040.6335.69Aug 3145.96Jan 12
201940.8236.11Jul 2045.57Dec 26
201844.2337.07Jan 1946.05Mar 1
201739.8029.79Sep 2945.68Nov 29
201641.2829.65Mar 1345.89Dec 2
201541.5029.62Mar 446.02Nov 27
201441.8029.27Sep 2545.67Mar 30
201340.2325.19Sep 2646.22Jan 28
201235.7830.65Aug 1546.04Mar 3
2011 (151 days)42.2339.83Oct 1646.08Dec 14

Levels in feet. Partial years show the number of days with data.

Monthly averages

MonthAverageLowestHighest
January41.9132.2046.22
February41.4130.5946.03
March41.7329.6246.16
April41.9531.4646.04
May42.7035.2345.67
June40.5931.1145.56
July39.3131.0145.82
August38.0930.5045.82
September37.1725.1945.95
October38.3027.2445.91
November39.9525.3246.02
December41.8030.6546.08

Download

Daily levels as CSV (5,426 rows; credit the original agencies listed below)