Idaho River Levels
The biggest water of a Idaho year runs on a calendar, and the calendar is below, drawn from USGS's own records. So are 6 gauges read live against their NWS flood stages, the live NWS alert feed, and the flash flood rules that matter here precisely because most floods do not wait for the calendar.
Idaho rivers normally carry their biggest water in May and JulyWhere Idaho rivers stand against their flood stages
Each card below carries two numbers from two agencies: the stage USGS is reporting at the gauge right now, read live from waterservices.usgs.gov when this page loaded, and the flood stage NWS has established for that same gauge. The “above” or “below” line is the subtraction between them and nothing more. A gauge below its thresholds is exactly that, not a promise about the next storm.
Reading current stage from waterservices.usgs.gov.
Stages are the U.S. Geological Survey's own readings, fetched live in your browser and shown without adjustment; provisional data are marked and may be revised by USGS. The action, minor, moderate and major thresholds are established per gauge by the National Weather Service and were snapshotted from the National Water Prediction Service; “above” or “below flood stage” is arithmetic on those two agency numbers and nothing more. A reading describes the gauge's own reach, not any particular property near it. Sources: USGS and NWS NWPS
Find the gauges nearest you
Every reading on this page belongs to one gauge on one reach of river, and the gauge nearest you is the one describing your water. This tool ranks the Idaho gauges on this page (and, where the state line is closer than the water, the rest of the site's registry) by distance from a ZIP code, with each gauge's live stage against its flood stage. The distance is printed on every row because a gauge 40 miles away describes that river, not your street.
Active NWS flood products for Idaho
Gauges show water that has already arrived. Warnings arrive first, and they cover the thousands of Idaho streams that have no gauge at all, which is where flash floods do their killing. This feed is read live from api.weather.gov and republished exactly as NWS issued it.
Reading active alerts from api.weather.gov.
Republished as issued by the National Weather Service, read live from api.weather.gov when this page loaded. Coastal and lakeshore flood products are not listed here; find them with everything else at weather.gov.
The product names have precise meanings. A Flood Warning, in NWS's words, is “a release by the NWS to inform the public of flooding along larger streams in which there is a serious threat to life or property”. A Flash Flood Warning means flash flooding is in progress, imminent, or highly likely: act first, check the river later.
What flood stage means at each Idaho gauge
Flood stage is not one number. NWS establishes a ladder of thresholds for each individual gauge, in feet of stage at that gauge, because the same depth of water means different things in different valleys. Here is Idaho's committed ladder, then the agency's own definitions of each rung.
| Gauge | County | Action | Flood | Moderate | Major | Record crest |
|---|---|---|---|---|---|---|
| Snake River At Weiser Id | Washington | 11.5 ft | 12 ft | 13.5 ft | 14.5 ft | 15.6 ft (1972) |
| Bear River At Pescadero Id | Bear Lake | 6 ft | 6.3 ft | none set | none set | 6 ft (2017) |
| Kootenai River At Bonners Ferry Id | Boundary | 57 ft | 64 ft | 70 ft | 78 ft | 80.1 ft (1961) |
| Salmon River At Salmon Id | Lemhi | 7 ft | 7.5 ft | 8.5 ft | 9.5 ft | 10.3 ft (1985) |
| Clearwater River At Spalding Id | Nez Perce | 17 ft | 18 ft | 19 ft | 19.4 ft | 27.8 ft (1963) |
| Snake River near Minidoka Id At Howells Ferry | Minidoka | 10.2 ft | 11.5 ft | none set | none set | 16 ft (1918) |
Thresholds are the National Weather Service's established gage heights for each point, snapshotted from the National Water Prediction Service on 2026-09-02; they change rarely. “None set” means NWS has not established that category for the gauge, which is common at remote points. Record crests are NWS's own historic crest listings.
National Weather Service Glossary, Action Stage“The stage which, when reached by a rising stream, represents the level where the NWS or a partner/user needs to take some type of mitigation action in preparation for possible significant hydrologic activity. The appropriate action is usually defined in a weather forecast office (WFO) hydrologic services manual.”
National Weather Service, High Water Level Terminology“Minor Flooding is defined to have minimal or no property damage, but possibly some public threat. A FLOOD ADVISORY product is issued to advise the public of flood events that are expected not to exceed the minor flood category.”
National Weather Service, High Water Level Terminology“Moderate Flooding is defined to have some inundation of structures and roads near the stream. Some evacuations of people and/or transfer of property to higher elevations may be necessary. A FLOOD WARNING should be issued if moderate flooding is expected during the event.”
National Weather Service, High Water Level Terminology“Major Flooding is defined to have extensive inundation of structures and roads. Significant evacuations of people and/or transfer of property to higher elevations are necessary. A FLOOD WARNING should be issued if major flooding is expected during the event.”
The threshold names and definitions are the National Weather Service's; the one line glosses above each quote are ours.
National Weather Service, High Water Level Terminology“Flood categories are terms defined for each gage location that describe or categorize the observed or expected severity of flood impacts in the corresponding stream segment or nearby stream. The severity of flooding at a given stage is not necessarily the same at all locations along a stream due to varying channel/bank characteristics on portions of the stream.”
What NWS says happens at these stages, in its own words
For 6 of these gauges, NWS publishes impact statements: sentences tied to specific stages, naming the roads and places that go under. They are the most local flood information that exists for these reaches, they are federal writing republished verbatim, and they are exactly what the thresholds above are made of.
Snake River At Weiser Id
NWS impact statement, National Water Prediction Service“Flooding of agricultural land near the river is likely in Malheur County, Oregon and in Washington County, Idaho. Mortimer Road in Weiser will be flooded.”
NWS impact statement, National Water Prediction Service“Major flooding will occur near the river, with extensive flooding of agricultural land in Malheur County, Oregon with several county roads underwater. Significant flooding will also occur in Weiser, Idaho with floodwater covering the water treatment plant on Mortimer Road.”
Bear River At Pescadero Id
NWS impact statement, National Water Prediction Service“Lowland and crop field flooding is possible below the Grace Power Plant Works especially in the Thatcher Flats to head of Oneida Narrows Reservoir.”
Kootenai River At Bonners Ferry Id
NWS impact statement, National Water Prediction Service“There will be minor flooding along the agricultural lands of the Kootenai Valley due to seepage and high water tables. Some private roads near the levees may also experience minor flooding from seepage.”
NWS impact statement, National Water Prediction Service“Flooding on Main Street in Bonners Ferry and into the buildings. Seepage through levees increases.”
Why Idaho's high water keeps a schedule
May and July are the high months at these gauges in our reduction of USGS's own daily medians. In the mountain West that peak is the snowpack coming down on the warm season schedule, so its size is largely known months ahead; on the southern plains the same months are simply the peak of the storm season. The dangerous years are the ones where heavy rain lands on top of the scheduled peak.
The deepest water on this page's record: 80.1 feet at Kootenai River At Bonners Ferry Id in 1961, which is 16.1 feet above that gauge's flood stage. NWS keeps the crest lists, and its definition is the useful one here:
National Weather Service, High Water Level Terminology“Record flooding is flooding that equals or exceeds the highest stage or discharge at a given site during the period of record keeping.”
The part no gauge can do
NWS flood safety, quoted verbatimMost Idaho streams have no gauge, and flash floods happen on exactly that water. NWS says both halves of this plainly, and its words belong on this page more than any reading does.
First, who dies in floods, from the agency that counts:
National Weather Service, Turn Around Don't Drown“Each year, more deaths occur due to flooding than from any other thunderstorm related hazard. The Centers for Disease Control and Prevention report that over half of all flood-related drownings occur when a vehicle is driven into hazardous flood water. The next highest percentage of flood-related deaths is due to walking into or near flood waters.”
National Weather Service, Turn Around Don't Drown“A mere 6 inches of fast-moving flood water can knock over an adult. It takes just 12 inches of rushing water to carry away most cars and just 2 feet of rushing water can carry away SUVs and trucks. It is NEVER safe to drive or walk into flood waters.”
National Weather Service, Turn Around Don't Drown“Never drive around the barriers blocking a flooded road. The road may have collapsed under that water.”
Those three passages are the NWS Turn Around Don't Drown campaign in full working order, and they apply to every water crossing in Idaho, gauged or not. Second, the limits of pages like this one. NWS, writing about the state with more rivers and fewer gauges than any other, is candid about the network:
National Weather Service, High Water Level Terminology“There are uncountable numbers of streams and lakes of various sizes in Alaska and only a very small fraction of these have gages that monitor the water levels.”
National Weather Service, High Water Level Terminology“People living or recreating near any stream or lake should identify the closest gage that can be used as an index for the expected water level changes at their location.”
That is the frame for everything above: a gauge is an index for its reach, the nearest one is worth knowing, and a Flash Flood Warning outranks any reading on this page. The NWS definition that makes the speed clear:
National Weather Service Glossary, Flash Flood“A rapid and extreme flow of high water into a normally dry area, or a rapid water level rise in a stream or creek above a predetermined flood level, beginning within six hours of the causative event (e.g., intense rainfall, dam failure, ice jam). However, the actual time threshold may vary in different parts of the country. Ongoing flooding can intensify to flash flooding in cases where intense rainfall results in a rapid surge of rising flood waters.”
Flood zones are FEMA's to determine. Whether a property sits in one is an official determination tied to flood insurance, and it is made on FEMA's own maps. In FEMA's own words:
FEMA Flood Map Service Center“The FEMA Flood Map Service Center (MSC) is the official public source for flood hazard information produced in support of the National Flood Insurance Program (NFIP). Use the MSC to find your official flood map, access a range of other flood hazard products, and take advantage of tools for better understanding flood risk.”
Look up any address at msc.fema.gov.
Where the Idaho figures come from
Two agencies, kept apart. The readings are live from USGS: stage from the instantaneous values service, discharge and its percentile context from the same daily services the drought pages use. The thresholds, impact statements and crests are NWS's, snapshotted from the National Water Prediction Service on 2026-09-02; flood stages are established gage heights that change rarely, and the snapshot date is printed wherever they appear. The alerts are live from api.weather.gov.
Which gauges appear is our choice, made once and stated plainly: active USGS stage gauges that NWS resolves to a forecast point with a published flood stage, ranked by drainage area so the rivers people actually check come first, at most two per river, spread across the state, with canals and diversions excluded. Gauges below dams are kept on purpose: regulated or not, they are the gauges downstream towns watch. The thing that is missing on purpose: there is no flood score, index or rating of ours anywhere on this site, and no flood zone map either. NWS owns the thresholds, USGS owns the readings, FEMA owns the maps.
Sources: USGS Water Data for the Nation, NWS National Water Prediction Service, NWS flood safety, and FEMA Flood Map Service Center.
A note on what the National Water Prediction Service is, in our words. It is the NWS platform that carries every official river gauge page: observed stages, forecast crests where a river forecast center issues them, the flood stage ladder, impact statements and historic crests. When a reading on this page makes you want a second opinion, the NWPS gauge page linked on every card is the authoritative one.
Our summary of information published by NWS National Water Prediction Service
Idaho river levels FAQ
The same water, other seasons
River levels in nearby states
Stage and discharge readings are the U.S. Geological Survey's, read live in your browser and shown without adjustment. Flood stage thresholds, impact statements and historic crests are the National Weather Service's, snapshotted from the National Water Prediction Service and dated where they appear. Alerts are republished as NWS issued them. Flood zone determinations are FEMA's alone. This page is a state level index: early summer high water is a fact about the gauges above (Idaho's biggest watched gauge sits under the 93,000 square mile line), not about any address. National picture: river levels in every state