American Falls Reservoir
American Falls Reservoir is managed by U.S. Bureau of Reclamation. Lake Insights displays its latest available elevation from U.S. Bureau of Reclamation (USBR). Published reference elevations are listed below.
Lake Status
47.45 feet below full pool
−47.45 ft vs full pool
- 7-day trend
- Falling
- 7-day change
- Down 0.84 ft
- 30-day change
- Down 0.84 ft
- Last updated
- Sep 10 • 12:00 AM
American Falls Reservoir is currently 47.45 feet below full pool and has been falling over the past week. Readings show continued drawdown relative to full pool, with levels trending lower over the past week.
Watershed drought conditions
Power County, ID · surrounding county from lake location
Extreme Drought
Extreme drought conditions are present.
Severity
Weekly trend
Stable
Compared with last week
Official drought
Yes
100% of the watershed is currently classified as official drought (D1+).
Expected impacts
- Significantly reduced stream inflows
- Lake levels may fall quickly without heavy rain
- Dry vegetation and elevated wildfire risk
- Water use restrictions may apply nearby
U.S. Drought Monitor · map date Sep 8, 2026. Updated weekly. droughtmonitor.unl.eduView drought map for Power County, ID
Key Facts
Managing authority
Waterbody / project type
Official purposes
Full pool
Datum
Current-level source
Project / NID identifier
Dam / watershed (NID design values)
Static design values from a confidently matched National Inventory of Dams record — not live gage readings.
- Normal storage
- 1.67M acre-ft
- Surface area at normal pool
- 58,076 acres
- Drainage area
- 14,560 sq mi
- Spillway capacity (design)
- 86,750 cfs
- Dam structure
- Concrete · 104 ft high · completed 1927
- Hazard classification
- High
- Safety & inspection
- last inspection Apr 25, 2022
National Inventory of Dams · matched record: American Falls Dam (ID00274)
How this lake is operated
- Documented project purposes (National Inventory of Dams): Flood Risk Reduction, Fire Protection, Stock, Or Small Fish Pond, Fish and Wildlife Pond, Recreation.
Why the level can change
General factors for reservoirs like this
These are common influences for this type of lake. They do not identify the cause of a specific current change unless an operator update confirms it.
Rainfall & inflows
Rain and upstream river inflows can raise reservoir levels, especially after storms.
Downstream releases
When an operator releases water through a dam, reservoir storage can fall and downstream flows can rise.
Flood-risk operations
Some projects store or release water under flood-risk rules when conditions require it.
Water supply
Some reservoirs support municipal, industrial, irrigation, or regional water-supply needs.
Hydropower
Hydropower projects may pass water through turbines when generating electricity.
Seasonal weather
Dry periods, heat, evaporation, and seasonal rainfall patterns can affect storage over weeks and months.
Published reference elevations
- Full pool
- 4355.00 ft
Published reference elevation. Not necessarily a fixed year-round target for every project.
Current data source
Managing authority: U.S. Bureau of Reclamation
Observation source used by Lake Insights: U.S. Bureau of Reclamation (USBR)
Who manages the lake and who publishes the reading Lake Insights displays can differ. Lake Insights does not invent a source label from the managing authority alone.
General education
Shared background — not lake-specific facts
Lake Insights aggregates water level information from authoritative public sources such as the U.S. Army Corps of Engineers, NOAA, TVA, Bureau of Reclamation, power utilities, and other official lake operators. We preserve historical observations, calculate trends, and present lake conditions in a consistent format. For U.S. Bureau of Reclamation (USBR), we link to the official source whenever it is available. Lake Insights does not predict future lake levels unless an official forecast has been published by the managing authority.
Common questions about American Falls Reservoir
- Who manages American Falls Reservoir?
- American Falls Reservoir is managed by U.S. Bureau of Reclamation. Lake Insights reports published gauge readings; it does not operate the waterbody.
- What is full pool at American Falls Reservoir?
- The published full-pool elevation for American Falls Reservoir is 4355.00 ft (NGVD29). Full pool is a published reference elevation — not a prediction of today’s level.
- Where does Lake Insights get the level reading for American Falls Reservoir?
- Lake Insights displays the latest available elevation for American Falls Reservoir from U.S. Bureau of Reclamation (USBR). The managing authority (U.S. Bureau of Reclamation) may differ from the agency that publishes the observation used on this page.
- What datum is used for American Falls Reservoir?
- Elevations for American Falls Reservoir are referenced to NGVD29 (MSL).
- What are the documented purposes of American Falls Reservoir?
- Documented purposes for American Falls Reservoir (National Inventory of Dams): Flood Risk Reduction, Fire Protection, Stock, Or Small Fish Pond, Fish and Wildlife Pond, Recreation.