A river crest is the highest water level a gage records during a rise. The National Weather Service hydrograph for the Spokane gage lists a historic crest of 28.73 feet in January 1974 and a 2023 crest of 25.50 feet, which the service marks as preliminary. A crest figure describes the gage, not the house.
Key takeaways
- A crest is the peak level at a gage at one point in time, and it does not say how much water reached a particular building.
- The NWS hydrograph lists a historic crest of 28.73 feet in January 1974 and a 2023 crest of 25.50 feet, the latter marked preliminary.
- Preliminary figures can change after review, so the number should be checked on the source page before it is quoted.
- The Spokane County Flood Insurance Study names December 1933 as the largest flood with water-surface data, at about 47,800 cubic feet per second.
- A crest should be read together with the ground, the floor level and the drains of the house it is being compared with.
What does a crest figure actually measure?
A crest figure is the highest water level a gage records during a rise. It is a reading at one place on the river, taken at one time, and it describes the river at that point rather than any building near it.
A gage is a measuring station on the river that records the water surface. The highest reading during an event is the crest. Hydrographs plot the level over time, so the rise, the peak and the fall can be read from one chart.
Because the gage is fixed in one place, the crest tells you how high the river got there. The water at a house a few streets away, or at a basement set on the ground above or below the gage, can be higher or lower depending on the land between them.
What do the Spokane figures say?
The NWS hydrograph lists a historic crest of 28.73 feet in January 1974 and a 2023 crest of 25.50 feet. The 2023 figure is marked preliminary, which means it was reported before the record was reviewed.
Those two figures are the recent crests on the Spokane gage. They show that the river has reached high levels within the lifetime of many residents, and that a rise of that size is a real possibility in a wet year.
The table below sets the figures against other records in the Spokane County Flood Insurance Study and the county hazard mitigation plan. Each row shows what the source says and what it does not say.
| Event | What the source states | What it does not state |
|---|---|---|
| January 1974 crest | 28.73 feet at the Spokane gage, NWS hydrograph | Damage to any single house |
| 2023 crest | 25.50 feet, marked preliminary, NWS hydrograph | The final reviewed figure |
| December 1933 | Largest flood with water-surface data, about 47,800 cubic feet per second, flood insurance study | The height at any street |
| May 1894 | Highest on record since gaging began, flood insurance study | The volume or the damage |
| February 1996 | Affected Spokane County among 24 Washington counties, county mitigation plan | The damage count for the county |
What does preliminary mean on a crest figure?
Preliminary means the figure was reported before the agency reviewed the data. It can be revised, so a preliminary crest should be checked against the current source before it is quoted in a claim, a sale or a repair decision.
Gage readings are checked for errors, for instrument problems and for the rating curve that turns a water level into a flow. Those checks can change a figure after the event, which is why the agency marks an early figure as preliminary.
The homeowner's practical rule is simple. Use the crest figure as a guide to how high the river has gone, and check the source page for the current value before you put a number in writing.
What does the flood insurance study add?
The Spokane County Flood Insurance Study names the largest recorded floods with water-surface data and describes the flood types for the county. It adds the historic context that a single gage reading cannot give.
The study names December 1933 as the largest flood with water-surface data, at about 47,800 cubic feet per second, and gives a May 1894 flood as the highest on record since gaging began. Those records are the outer range of the county's flood history.
The study also describes spring snowmelt floods and winter rain-on-snow events as the two main flood types, and it notes that Coeur d'Alene Lake reduces peak flows on the lower river. A crest is one number; the study explains the causes behind the numbers.
How does a crest relate to the water in my house?
The crest is a river measurement, and the water in a house depends on the house's floor level, its drains, its grade and the route the water takes to it. Two houses a short distance apart can take very different amounts of water in the same event.
A basement below the level of the river can take water through the drains and the foundation even when the river is well below the top of its bank. A house on a rise can stay dry through a crest that floods the streets below it.
A useful comparison is between the water line on your own walls and the crest figure. The line shows how high the water reached at your house, and the crest shows how high the river reached at the gage. Those two figures together say more than either one alone.
What should I record when water is near my home?
Record the date and time, the height of the water on the house, the source you think it came from and the weather before and during the event. Keep photographs with a measuring tape in the frame, so the water line can be measured later.
A dated set of photographs is the most useful record of an event. It lets you compare the water line with the crest figure afterward, and it gives an insurer and a contractor the same facts.
If a crew visits, ask it to record the water line on each wall and the depth of the water at the lowest point. The crew's record and your own photographs should agree, and any difference is worth asking about.
How should I use a crest figure when I plan repairs?
Use the crest figure to understand the range of high water the river can produce, and use the water line in your house to decide what must be repaired. A repair plan that follows the house's own water line is more reliable than one that follows a gage reading alone.
A lower level that took water to a certain height needs its finishes removed to at least that height, plus a margin set by the readings. The crest tells you the river could rise higher, which is a reason to think about the floor level and the drains as well.
A grading contractor, a plumber or a flood-mitigation specialist can read the house and the lot together with the crest history. The crew's written record gives them the water line and the readings they need to start.
Where should I check current river levels?
Check the National Weather Service hydrograph for the Spokane gage, which is the source that lists the historic and 2023 crests. Check it before you quote a figure, because preliminary values and current readings can change.
The NWS hydrograph shows the river's level over time for the gage. Read the date and the status of each figure, and treat a preliminary value as provisional until it is reviewed.
The Spokane County flood insurance study and the county hazard mitigation plan are the sources for the wider flood history. Use them to understand the range and the causes, and use the gage for the level at the gage.
How is a flood stage read on a creek gage?
A flood stage is a gage level above which the water is considered to be flooding. The Hangman and Latah gauge at Spokane has a flood stage of 11.0 feet, and a National Weather Service bulletin of February 24, 2025 showed the water at 12.7 feet in the prior 24 hours.
The bulletin is a useful example of how the figures fit together. The current level is compared with the flood stage, the crest forecast is given as a separate number, and the warnings are tied to the homes in the area the bulletin names. A reader can see both how high the water was and how much above the stage it had risen.
The forecast crest in that bulletin was 12.3 feet, below the level already reached. Forecasts change as the water moves, which is why a crest forecast is not the same thing as a measured crest, and why the measured figure is the one to keep once it is published.
How should a homeowner use the bulletin?
Use a bulletin to decide whether to prepare, not to measure the house. Move valuables, check the power and the drains, and photograph the lower level before the water arrives, because the bulletin describes the gage and not the building.
A bulletin that warns of homes in a valley is a signal to check the low spots on your own property. The bulletin cannot say whether your basement will take water, so the preparation is based on your own floor level, drains and the route the water takes to the house.
After the event, compare the water line on your walls with the crest or peak level in the bulletin. The gage level and the house level together explain what happened better than either figure on its own.
Frequently asked questions
What is the highest the Spokane River has crested?
The NWS hydrograph lists a historic crest of 28.73 feet in January 1974 at the Spokane gage. The Spokane County Flood Insurance Study also names a May 1894 flood as the highest on record since gaging began.
Does a crest number tell me if my house will flood?
No. The crest is a level at the gage, and the water in a house depends on its floor level, drains, grade and the route the water takes. Use the crest for the range and the water line on your walls for the house.
Why is the 2023 crest marked preliminary?
The figure was reported before the agency reviewed the data, so it can change. Check the current NWS page before you quote the number in a claim or a repair plan.
What is the difference between a crest and a flood stage?
A crest is the peak level reached during a rise. A flood stage is a level at which the river is considered to be flooding at a given gage. The two terms should be read from the specific gage's page, which lists both where they apply.
Who decides whether a crest figure is accurate?
The agency that operates the gage reviews the data and can revise it. The homeowner's job is to check the current source and to record the water line on the house, which is evidence the crest figure cannot provide.
Sources
- National Weather Service, Advanced Hydrologic Prediction Service, Spokane gage hydrograph
- City of Spokane, Spokane County Flood Insurance Study
This guide is general information for Spokane County homeowners, not a substitute for an on-site inspection. Prices are estimates. See our disclaimer.