Water Supply

Idaho water supply information is provided through the combined efforts of state and federal governmental agencies involved in water management in Idaho. Each agency brings a different technical aspect and expertise in order to provide the most extensive water supply outlook available.

The following are technical data sources used by the Water Supply Committee to prepare the comprehensive water supply outlook.


River Flows for Recreationists
Flow in cubic feet per second for rivers of local interest.

River Flow Information By River
Real-time data from Idaho Power's website

River Flow Information by River
Real-time data from the USGS website

Surface Water Data
U.S. Geological Survey

Western U.S. Streamflow Forecast Map
Monthly forecasts provided by the NRCS


Idaho Snow Survey
Natural Resources Conservation Service

National Snow Information
Daily Snowdepth and Snow fall information from the Climate Prediction Center

Northwest SNOTEL Summary
Pacific Northwest Region summary from the USBR

Satellite Snow Cover Maps(By Month)
Satellite Areal Extent of Snow Cover from NRCS/NWCC

Snow Cover Information (By Location)
Graphic snow parameter for Western US and Columbia Basin from NWS

Western US SNOTEL Information
Narrative and mapped Snotel climate information from the WRCC

West-wide Snowpack Map
Monthly mountain snowpack maps

Snow Water Equivalent
View weekly IDWR Maps showing snowpack measurement in Idaho.

Reservoir Storage

Boise and Payette River Systems
Reservoir levels and average daily streamflows from the USBR

Pacific Northwest System Information
Reservoir Data is under Report List on this page from USCE

River Basin Reports
Near real-time Pacific Northwest water and environmental data from the USBR

Upper Snake River System
Reservoir levels and average daily streamflows from the USBR

Mackay Reservoir Levels
USGS data page for Mackay Reservoir near Mackay Idaho

Precipitation & Weather

Climate Prediction Center

Idaho Annual Average Precipitation (Graphical map)

Idaho Climate Summaries
Interactive map from Western Regional Climate Center

National Long Range Precipitation & Temperature Outlook
WRCC (1 Year by 90-Day Intervals)

Idaho Evapotranspiration Charts
U.S. Bureau of Reclamation crop water use charts

Idaho Weather Forecasts
National Oceanic and Atmospheric Administration

National 10-Day Precipitation Outlook
Institute of Global Environment and Society

National 10-Day Temperature Outlook - IGES

Northwest Weather Radar Summary
Intellicast summaries

Northwest Precipitation Outlook
Updated every 6 hours at Intellicast

Western Regional Climate Center

El Niño

Basic Facts & Background
How to determine if an El Niño event is occurring today from NOAA.

Frequently Asked Questions
Commonly asked questions and their answers from the Western Regional Climate Center.


Drought Assessment Information
Weekly US drought assessment from the Climate Prediction Center of NOAA.

Palmer Drought Index
Color coded map of the United States from NOAA.

Drought Declarations Issued by IDWR
A list of counties that have been issued Drought Emergency Declaration Orders for the current calendar year.