Measuring streamflow on Grouse Creek, Moran, Wyoming, June 18, 2019. Photograph by Cheryl Miller, U.S. Geological Survey.
This U.S. Geological Survey summary describes the nation's streamflow in water year 2019 — October 1, 2018, to September 30, 2019 — ranked against the 90 water years from 1930 to 2019. It uses observed data from the USGS National Streamgage Network; before 1930 there were too few gauges for meaningful statistics in most regions. Some of the data are provisional.
How to read the rankings
- Runoff is the water flowing in a stream divided by the area of its drainage basin, so places of different sizes can be compared. For an area and period it is computed from every gauge there with a complete record.
- Rank 1 is the highest flow of the 90 years; rank 90 the lowest.
- Ranks fall into five groups by percentile of flow:
| Category | Percentile of flow | Rank |
|---|---|---|
| Much below normal | under 10% | 82–89 (90 = driest) |
| Below normal | 10–24% | 69–81 |
| Normal | 25–75% | 23–68 |
| Above normal | 76–90% | 10–22 |
| Much above normal | over 90% | 2–9 (1 = wettest) |
A record high or low is not shown where ranks tie. Puerto Rico and the Virgin Islands have 76 years of data, and their ranks are adjusted accordingly.
The nation
Runoff in the contiguous United States was 13.62 inches, far above the 1930–2019 mean of 9.37 inches. Water year 2019 ranked highest of the 90 years.
Figure 1. Annual runoff in the contiguous United States, water years 1930–2019.
By state
| Category | States |
|---|---|
| Record high | Illinois, Indiana, Kansas, Maryland, Michigan, Minnesota, Nebraska, New Jersey, Ohio, Oklahoma, Rhode Island, South Dakota, Wisconsin |
| Much above normal | Arkansas, Connecticut, Delaware, District of Columbia, Iowa, Kentucky, Louisiana, Massachusetts, Missouri, New Hampshire, New York, North Carolina, North Dakota, Pennsylvania, Tennessee, Texas, Vermont, Virginia, West Virginia |
| Above normal | Alabama, California, Georgia, Maine, Mississippi, Nevada, Utah |
| Below normal | Alaska, Hawaii, Oregon |
| Much below normal | Washington — the only one |
Figure 2. Statewide streamflow ranks for water year 2019.
Regions
The United States, Puerto Rico and the Virgin Islands are divided into 21 water-resources regions — large drainages based on the land surface: a major river's basin, several rivers together (the Texas-Gulf region, for example, holds several rivers draining to the Gulf of Mexico), or an island or island group.
Figure 3. Water-resources regions.
| Category | Regions |
|---|---|
| Record high | Arkansas-White-Red, Great Lakes, Mid-Atlantic, Missouri, Ohio, Upper Mississippi |
| Much above normal | Lower Mississippi, New England, Tennessee, Texas-Gulf |
| Above normal | California, Great Basin, Rio Grande, Souris-Red-Rainy, South Atlantic-Gulf |
| Below normal | Alaska, Hawaii, Pacific Northwest |
Figure 4. Regional streamflow ranks for water year 2019.
Season by season
| Autumn (Oct–Dec 2018) | Winter (Jan–Mar 2019) | Spring (Apr–Jun 2019) | Summer (Jul–Sep 2019) | |
|---|---|---|---|---|
| National rank | 1st of 90 | 2nd | 2nd | 14th |
| Record high | District of Columbia, Iowa, Louisiana, Maryland, New Jersey, North Carolina, Pennsylvania, Rhode Island, Texas, Virginia, Wisconsin | Iowa, Minnesota, Nebraska, South Dakota | Illinois, Kansas, Michigan, South Dakota, Wisconsin | South Dakota |
| Much above normal | Alabama, Connecticut, Delaware, Georgia, Indiana, Kansas, Kentucky, Massachusetts, Michigan, Minnesota, Nebraska, New Hampshire, New York, Ohio, South Carolina, South Dakota, Tennessee, Vermont, West Virginia | Arkansas, District of Columbia, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Missouri, New Jersey, Ohio, Tennessee, Virginia, Wisconsin | Arkansas, Indiana, Iowa, Louisiana, Maine, Minnesota, Mississippi, Missouri, Nebraska, New Hampshire, Ohio, Oklahoma, Pennsylvania, Texas, Vermont | Arkansas, Colorado, Illinois, Kansas, Minnesota, Missouri, Nebraska, North Dakota, Oklahoma, Wisconsin |
| Above normal | Arkansas, Florida, Illinois, Mississippi, Oklahoma | Alabama, Arizona, California, Connecticut, Delaware, Georgia, Massachusetts, Mississippi, North Carolina, North Dakota, Oklahoma, Pennsylvania, Rhode Island, South Carolina, Texas, West Virginia | California, Connecticut, Delaware, Kentucky, Maryland, Nevada, New Jersey, New York, North Carolina, North Dakota, Oregon, Rhode Island, Utah | California, Iowa, Louisiana, Michigan, Mississippi, Nevada, Ohio, Utah |
| Below normal | California, Oregon, Utah | Idaho, Oregon, Puerto Rico and the Virgin Islands | Puerto Rico and the Virgin Islands | Alabama, Georgia, Hawaii, South Carolina |
| Much below normal | Colorado | Washington | Hawaii, Washington | Alaska, Arizona, Washington |
Figure 5. Autumn (October–December 2018) statewide ranks.
Figure 6. Winter (January–March 2019) statewide ranks.
Figure 7. Spring (April–June 2019) statewide ranks.
Figure 8. Summer (July–September 2019) statewide ranks.
High and low flows
If gauges were independent and flows normally distributed, in any month about 5 percent of gauges would be expected to run high (above their 95th percentile) and 5 percent low (below their 5th). In water year 2019, every month had more high-flow gauges than expected — and no month had more low-flow gauges than expected.
| Month | Oct | Nov | Dec | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Gauges with high flow (%) | 14 | 22 | 18 | 11 | 14 | 8 | 10 | 15 | 9 | 7 | 6 | 7 |
Figure 9. Percentage of streamgages with high and low monthly streamflow, October 1999–September 2019.
More information
In water year 2019 the USGS ran more than 8,400 year-round, real-time streamflow gauges, with data at waterwatch.usgs.gov and state runoff summaries back to water year 1901. The network, part of the Groundwater and Streamflow Information Program, is operated mainly by the USGS and funded by it and about 1,400 federal, state, tribal, regional and local partners. Its data serve water management, flood and drought monitoring, bridge design and recreation.
Sources
- Jian, X., Wolock, D.M., Lins, H.F., and Brady, S.J., 2020, Streamflow—Water year 2019: U.S. Geological Survey Fact Sheet 2020–3057. https://pubs.usgs.gov/publication/fs20203057
- The figures, captions and photograph come from the fact sheet's PDF, which the web version lacks.
- Rewritten in hubnx's own words.
Licence: CC0 1.0 (public domain) · Adapted from pubs.usgs.gov
1
0
0
0
Comments
