North Dakota Drought Watch

Science Center Objects

Drought watch for North Dakota.

Drought Watch
Map of below normal 7-day average streamflow compared to historical streamflow for the week of the year

 Hydrologic Conditions







The "Below normal streamflow " map shows the average streamflow conditions for the past seven days, highlighting locations that are experiencing low flows or hydrologic drought. By averaging over an entire week, the values on the map are more indicative of longer-term streamflow conditions than either the "Real-time streamflow" or the "Daily streamflow" maps.

The map depicts 7-day average streamflow conditions as computed at USGS gaging stations. The colors represent 7-day average streamflow compared to percentiles of historical weekly streamflow for the week of the year. This map represents conditions adjusted for this time of the year. Only stations having at least 30 years of record are used. 

During winter months, fewer dots may appear than at other times of the year due to ice effects. The data used to produce this map are provisional and have not been reviewed or edited. They may be subject to significant change.


Drought Indicators

Click on one of the links below to see the maps

Lastest Condition Reports

Map of Real-Time Streamflow Compared to Historical Streamflow for the Day of the Year


Drought Information from State and Regional Agencies

Drought Information from Other Federal Agencies and National Organizations






What is a Percentile?

A percentile is a value on a scale of one hundred that indicates the percent of a distribution that is equal to or below it. For example, on the map of daily streamflow conditions a river discharge at the 90th percentile is equal to or greater than 90 percent of the discharge values recorded on this day of the year during all years that measurements have been made.  In general,

  • a percentile greater than 75 is considered above normal
  • a percentile between 25 and 75 is considered normal
  • a percentile less than 25 is considered below normal

In some hydrological studies, particularly those related to floods, a variation of the percentile known as the "percent exceedance" is used.  It is simply obtained by subtracting the percentile scale value  from 100 percent.  For example, a discharge at the 75th percentile is the same as a discharge at the 25th percent exceedance (100-75=25).


What is Provisional Data?

Data are provisional and subject to revision until they have been thoroughly reviewed and received final approval. Real-time data relayed by satellite or other telemetry are automatically screened to not display improbable values until they can be verified. Provisional data may be inaccurate due to instrument malfunctions or physical changes at the measurement site. Subsequent review based on field inspections and measurements may result in significant revisions to the data. Data users are cautioned to consider carefully the provisional nature of the information before using it for decisions that concern personal or public safety or the conduct of business that involves substantial monetary or operational consequences. Information concerning the accuracy and appropriate uses of these data or concerning other hydrologic data may be obtained from the USGS.