By Kurtiss Schmidt. USGS Fact Sheet 2021–3015, March 2021, prepared with the Nevada Department of Transportation.
A flood at the crest-stage gage on Ramsey Canyon Wash at Highway 50, Silver Springs (station 10312075), February 14, 2019. Photo: USGS.
Why Nevada counts its floods
Floods are among Nevada's most frequent and costly natural disasters:
- 1997: the New Year's flood did an estimated more than $1 billion in damage across northern Nevada.
- 2014: the remnants of Hurricane Norbert plus monsoon rains badly damaged more than 2 miles of Interstate 15 in southern Nevada.
They come from snowmelt, rain on snow, and flash floods in thunderstorms, at different seasons. Agencies need good estimates of peak streamflow to map flood zones and to design culverts, bridges and roads — and those estimates get better the longer the record behind them.
The program
Since 1961, the USGS and the Nevada Department of Transportation (NDOT) have recorded the annual peak streamflow — each year's highest flow — at selected sites, for use in flood-frequency analysis. Today the program covers 26 sites, measured with a network of crest-stage gages.
The 26 gage sites, numbered as in the table below. Map: USGS.
How a crest-stage gage works
A crest-stage gage records the highest water level reached between visits, with no power and no electronics:
- The pipe: in Nevada, typically a 2-inch pipe with vented caps at top and bottom.
- The stick: inside is a measuring stick, with granulated cork at the bottom of the pipe.
- The rise: as a flood rises, the cork floats up on the water inside.
- The mark: as the water falls, the cork sticks to the stick, leaving a line at the peak. Later, smaller peaks can leave marks too if cork remains.
A crest-stage gage's design (after Sauer and Turnipseed, 2010) and a stick marked by several peak flows. Figure: USGS.
Visits and measurements
- Routine: gages are visited about every 6 weeks to inspect and service them and to measure flow with current meters or other methods.
- Floods: crews also go during or right after a flood for direct or indirect measurements.
- Indirect: when the water is gone, the peak is modeled from surveys of the channel's shape, the high-water line, and any culverts or bridges.
Each site's annual peak goes into the USGS National Water Information System (NWIS), where anyone can look it up at nwis.waterdata.usgs.gov.
The record so far
The 26 sites hold 832 recorded peaks. Their drainage areas run from 0.62 to 1,542 square miles, and their largest peaks from 56 to 12,000 cubic feet per second.
Largest recorded peak at each site, through water year 2020:
| # | Site | Since | Drainage area (sq mi) | Date | Peak (cfs) |
|---|---|---|---|---|---|
| 1 | Muddy Wash near Moapa | 2012 | 7.8 | 09/26/2014 | 2,800 |
| 2 | Weiser Wash near Glendale | 1966 | 43 | 09/08/2014 | 12,000 |
| 3 | Echo Wash at Northshore Rd near Echo Bay | 1990 | 106 | 08/15/1990 | 6,000 |
| 4 | Cottonwood Valley near Blue Diamond | 1961 | 18.3 | 01/25/1969 | 1,100 |
| 5 | Piute Wash tributary at Searchlight | 1967 | 3.4 | 08/13/1982 | 400 |
| 6 | Dixie Creek Valley Tributary near Eastgate | 1961 | 11 | 08/1961 | 1,480 |
| 7 | Smith Creek Valley Tributary near Austin | 1968 | 0.62 | 07/1984 | 130 |
| 8 | Amargosa River at Hwy 127 near the California line | 1993 | 1,542 | 09/22/2007 | 660 |
| 9 | Lovell Wash near Blue Diamond | 1965 | 52.8 | 01/25/1969 | 4,150 |
| 10 | Indian Creek above mouth, near Gardnerville | 1986 | 25.4 | 02/19/1986 | 2,100 |
| 11 | Buckeye Creek at East Valley Road, near Minden | 1992 | 73.8 | 07/14/1992 | 3,000 |
| 12 | Genoa Canyon Creek at Genoa | 1997 | 2.24 | 01/01/1997 | 150 |
| 13 | Voltaire Canyon near Carson City | 1979 | 1 | 01/02/1997 | 118 |
| 14 | Brunswick Canyon near New Empire | 1966 | 12.7 | 01/08/2017 | 730 |
| 15 | Six Mile Canyon at Hwy 50 near Dayton | 1986 | 17.29 | 01/09/2017 | 663 |
| 16 | Ramsey Canyon Wash at Hwy 50 at Silver Springs | 2016 | 44.67 | 01/09/2017 | 669 |
| 17 | Gance Creek at Hwy 225 near Tuscarora | 1980 | 20.2 | 04/30/2006 | 109 |
| 18 | East Adobe Creek near Elko | 1971 | 6 | 07/27/1971 | 424 |
| 19 | Cole Creek near Palisade | 1962 | 11.4 | 06/1983 | 1,090 |
| 20 | Mill Creek near Battle Mountain | 2006 | indeterminate | 04/15/2009 | 56 |
| 21 | Mill Creek N. Channel near Battle Mountain | 2011 | indeterminate | 09/02/2013 | 56 |
| 22 | Pole Creek near Golconda | 1961 | 10.7 | 08/05/1961 | 4,000 |
| 23 | Jumbo Wash near New Washoe City | 1986 | 4.86 | 07/22/1986 | 1,230 |
| 24 | Long Valley Creek near Happy Valley | 1956 | 82.6 | 02/19/1986 | 5,400 |
| 25 | Pyramid Lake Tributary near Nixon | 1968 | 1.94 | 01/08/2017 | 1,220 |
| 26 | Johnson Wash at Fremont Dr near Minden | 1991 | 10.4 | 07/22/1994 | 1,400 |
"Since" is the water year each gage was established.
What the numbers are for
Records like these give estimates of how big and how often floods come. Engineers and planners use them to build structures that withstand floods, to designate flood zones, and to guide management and future planning, all to cut flood risk and damage.
Sources
Based on Peak Streamflow Determinations in Nevada: A Cooperative Program with the USGS and Nevada Department of Transportation, by Kurtiss Schmidt, USGS Fact Sheet 2021–3015, U.S. Geological Survey; a work of the United States government in the public domain. The import had lost the fact sheet's table, figures and map labels; the photograph, map, gage diagram and table come from its PDF.
Licence: CC0 1.0 (public domain) · Adapted from pubs.usgs.gov
1
0
0
0
Comments
