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Grassy Lake and Grassy Lake water level

Lake, Wyoming, United States

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Right now

Very low for mid-October

Surface elevation

7,179.78ft Up 0.24 ft over the last 7 days

Water stored
6,961 acre‑ft
7,180 7,190 7,200

History

History
7,1807,1907,200ftOct 13Oct 14Oct 15Oct 16Oct 187,1807,1907,200ftOct 13Oct 15Oct 18
7,1807,1907,200ftSep 20Sep 27Oct 4Oct 11Oct 187,1807,1907,200ftSep 20Oct 4Oct 18
7,1807,1907,2007,210ftOct 2025Jan 2026Apr 2026Jul 2026Oct 20267,1807,1907,2007,210ftOct 2025Apr 2026Oct 2026
7,1807,1907,2007,210ftOct 2016Apr 2019Oct 2021Apr 2024Oct 20267,1807,1907,2007,210ftOct 2016Oct 2021Oct 2026
7,1807,1907,2007,210ftJanMarMayJulSepNov20267,1807,1907,2007,210ftJanAprJulOct2026

202120222023202420252026

Surface elevation Normal range (10–90 %)

What this means

Grassy Lake and Grassy Lake is far below normal for mid-October, with the lake level at 7,179.78 ft.

The median for mid-October is 7,198.88 ft, based on 36 years of readings, so the lake level is 19.10 ft below typical. On the same day last year the reading was 7,191.45 ft, a difference of −11.67 ft.

It has risen 0.24 ft over the past week. In the last month it has stayed between 7,178.65 ft and 7,179.78 ft.

Lakes and reservoirs often sit lower in fall after a summer of evaporation and use, and recover with winter rain and spring snowmelt.

Compared with 36 years of daily readings for this time of year. How to read levels

Key numbers

Median for this date
7,198.88 ft19.10 ft below the median for this date
Normal for this date
7,187.20 ft – 7,200.39 ft8 years in 10 fall in this range (36 years of records)
Same day last year
7,191.45 ft−11.67 ft
Lowest and highest in 30 days
7,178.65 ft – 7,179.78 ft
Lowest and highest in 12 months
7,178.38 ft – 7,209.34 ft

On the water at Grassy Lake and Grassy Lake

A receding shoreline opens up beaches but also uncovers hazards: stumps, rocks and soft mud that are usually well under water.

Wear a life jacket on the water. Most boating deaths involve people who were not wearing one.

Weather at the gauge

The forecast is not available right now.

Sunrise 07:44 AM Sunset 06:34 PM Daylight 10 hr, 51 min First quarter 62%

Map

Nearby gauges

Gauge Level Compared with normal 24 hours Distance
Snake River above Jackson Lake at Flagg RanchRiver gauge, Snake River 2.40 ft Below flood stage −0.02 ft 8 mi
Fall River above Yellowstone Canal near SquirrelRiver gauge, Fall River 431 cfs Very low ±0 17 mi
Fall River near SquirrelRiver gauge, Fall River 216 cfs Very low +4.0 cfs 21 mi
Jackson Lake and Jackson LakeLake 6,734.21 ft Very low 22 mi
Snake River near MoranRiver gauge, Snake River 266 cfs Normal −19.0 cfs 22 mi
Firehole River at Old Faithful, YNPRiver gauge, Firehole River 37.7 cfs Very low −1.0 cfs 23 mi
Pacific Creek at MoranRiver gauge, Pacific Creek 4.27 ft Below flood stage −0.03 ft 24 mi
Fall River near AshtonRiver gauge, Fall River 445 cfs Very low −5.0 cfs 27 mi

Questions and answers

Is Grassy Lake and Grassy Lake higher than last year?

No, it is 11.67 ft lower than on the same day last year, when the reading was 7,191.45 ft.

What is a normal level for Grassy Lake and Grassy Lake in mid-October?

The median for mid-October is 7,198.88 ft. In 8 years out of 10 the reading falls between 7,187.20 ft and 7,200.39 ft, based on 36 years of records.

Is Grassy Lake and Grassy Lake really 7,179.78 ft deep?

No. 7,179.78 ft is the height of the water surface above sea level (or the agency's vertical datum), not the depth of the water.

What is the water level of Grassy Lake and Grassy Lake today?

On Oct 18, 2026, the surface elevation was 7,179.78 ft. Up 0.24 ft over the last 7 days.

Is Grassy Lake and Grassy Lake rising or falling?

Up 0.24 ft over the last 7 days.

Is the level of Grassy Lake and Grassy Lake normal?

Very low for mid-October. Compared with 36 years of daily readings for this time of year.

How often is this data updated?

The U.S. Bureau of Reclamation publishes a new reading once a day. This page refreshes within minutes of each update.

For specialists

Station codes, datum, parameters, data quality and downloads
Operator
U.S. Bureau of Reclamation
Station code
usbr:7178 (Agency page)
Coordinates
44.12966, -110.81939 (WGS84)
Update interval
once a day
Licence
Public domain. Data: U.S. Bureau of Reclamation (RISE), provisional data subject to revision

Published series

ParameterLast valueTime (UTC)Quality
Surface elevation 7,179.78 ft 2026-10-18 06:00 Provisional
Water stored 6,961 acre‑ft 2026-10-18 06:00 Provisional

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How to cite

U.S. Bureau of Reclamation: Grassy Lake and Grassy Lake (usbr:7178). Accessed October 19, 2026 via Nivelmap, https://nivelmap.com/en/united-states/wyoming/grassy-lake-and-grassy-lake

How we check values

Each reading is stored as published. We hold back values that jump faster than physically plausible and show the measurement time with every value.