Drought Monitor classification for streamflow gaging stations

The maps are currently under maintenance, please email Scott Young at rsyoung@usgs.gov if you have any questions.

U.S. Drought Monitor classification applied to median of “daily” percentiles for 7-day average flow, from through the previous 7, 14, 30, 60, and 90 days, at selected USGS streamflow gaging stations.

Description Unregulated Regulated DiversionA
No - No Drought (>30 percentile) No Drought icon No Drought icon No Drought icon
D0 - Abnormally Dry (21 to 30 percentile) Abnormally Dry icon Abnormally Dry icon Abnormally Dry icon
D1 - Moderate Drought (11 to 20 percentile) Moderate Drought icon Moderate Drought icon Moderate Drought icon
D2 - Severe Drought (6 to 10 percentile) Severe Drought icon Severe Drought icon Moderate Drought icon
D3 - Extreme Drought (3 to 5 percentile) Extreme Drought icon Extreme Drought icon Extreme Drought icon
D4 - Exceptional Drought (0 to 2 percentile) Exceptional Drought icon Exceptional Drought icon Exceptional Drought icon
n/d - Not determined Not determined icon Not determined icon Not determined icon

Note A: Streamflows characterized as being affected by "Diversions" are conditions that (may) reflect the presence of upstream minor regulation and (or) major point-source discharges or withdrawals caused by municipalities, power plants, and (or) industries located upstream from the streamgage.

    Map is assembled as follows:
  1. At each site, compute the “daily running” 7-day average flows and corresponding percentile based on historical 7-day flows for the given calendar date. See USGS WaterWatch pages for this particular statistic for each calendar day.
  2. Then for previous “x” days (where x = 7, 14, 30, 60, or 90), rank the computed daily percentiles and determine the median percentile for the indicated previous period.
  3. Relate the median percentile (corresponding percentile range shown in map explanation) to the U.S. Drought Monitor classification scheme for streamflow.
    Related Drought Links:
  • The Coastal Salinity Index (CSI) utilizes salinity data to characterize saline (drought) and freshwater (wet) conditions in coastal areas

7-day average streamflow
Median percentile previous 7 days through .

7-day average streamflow
Median percentile previous 14 days through .

7-day average streamflow
Median percentile previous 30 days through .

7-day average streamflow
Median percentile previous 60 days through .

7-day average streamflow
Median percentile previous 90 days through .