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WALKER RIVER - MASON (MASN2)
Latitude: 38.92º NLongitude: 119.19º WElevation: 4420 Feet
Location: Lyon County in NevadaRiver Group: Eastern Sierra
Issuance Time: Apr 23 2017 at 8:31 AM PDTNext Issuance: Apr 24 2017 at 9:00 AM PDT
Monitor Stage: 9.3 FeetFlood Stage: 9.8 Feet

SPECIAL NOTE:Provisional rating under development due to recent sediment removal. Increased uncertainty exists for both observed and forecast flows.

Observed Data Credit
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Raw streamflow data is provided by the US Geological Survey (USGS).
View USGS Data for this station location.

Verification - Historical Graphical RVF
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Historical Stage/Flow Data
Water Year
Peak Discharge (cfs)
Stage (feet)
Date
 Most Recent 5 Years
2015
361
6.41
Jul 11, 2015
2014
227
5.81
Jun 1, 2014
2013
347
6.24
Jun 5, 2013
2012
337
6.23
Apr 30, 2012
2011
2,420
10.77
Jul 01, 2011
 Historical High Stage/Flow Events (Period of Record - April 1974 to Present)*
1997
3,900**
12.72
Jan 04, 1997
1995
2,980**
11.57
Jul 11, 1995
1983
2,790***
11.31
Jun 19, 1983
2011
2,420
10.77
Jul 01, 2011
 * Break in data between Oct 1984 and Sept 2010.
 ** Calculated using other gages and MASN2 Rating #2.
 *** Measured stage converted. Crest calculated using MASN2 Rating #2.
Location Photographs
ESRI™ Locator Map
Official 7 Day National Weather Service Forecast   (NVZ001)
Tonight: Clear in the evening then becoming mostly cloudy. Lows 40 to 45. Northwest winds 10 to 15 mph. Gusts up to 35 mph in the evening.

Monday: Cloudy. Highs 58 to 68. Southwest winds around 10 mph increasing to west 15 to 25 mph with gusts up to 45 mph in the afternoon.

Monday Night: Mostly cloudy. Lows 40 to 45. Northwest winds 15 to 25 mph with gusts up to 45 mph decreasing to 10 to 15 mph after midnight.

Tuesday: Mostly cloudy. Highs 60 to 70. Northwest winds 10 to 15 mph. Gusts up to 30 mph in the afternoon.

Tuesday Night: Mostly cloudy. Slight chance of showers after midnight. Lows 46 to 51. Northwest winds 10 to 20 mph. Gusts up to 35 mph in the evening.

Wednesday: Mostly cloudy with a slight chance of showers. Highs 65 to 70.

Wednesday Night: Breezy. Mostly cloudy. Lows 36 to 46.

Thursday: Mostly cloudy. Highs 56 to 66.

Thursday Night: Breezy. Partly cloudy. Lows 32 to 42.

Friday and Friday Night: Clear. Highs 54 to 59. Lows 32 to 42.

Saturday and Saturday Night: Clear. Highs 59 to 69. Lows 34 to 44.

Sunday: Sunny. Highs 64 to 74.
Impacts - E19 Information
9.3 FeetMonitor Stage. No flooding in the Mason Valley-Yerington area. About 1550 cfs. Chances of exceeding this flow any year about 1 in 3 per USGS estimate.
9.8 FeetFlood Stage. Minor lowland flooding begins throughout Mason Valley-Yerington area. About 1850 cfs. Chance of exceeding this flow any year about 1 in 4 per USGS estimate.
10.0 FeetMinor flooding of lowlands, pasture, cropland and some rural roads throughout the Mason Valley-Yerington area. No flooding of structures of roads. About 1950 cfs. Chance of exceeding this flow any year about 1 in 5 per USGS estimate.
10.3 FeetMinor flooding of lowlands, pasture, and farmland in Mason Valley-Yerington area. Preventative sandbagging of lowest homes and businesses adjacent to river should begin if further rises are possible, but little flooding occurs. Some isolated flooding of rural roads. About 2150 cfs. Chance of exceeding this flow any year about 1 in 6 per USGS estimate.
10.5 FeetMinor flooding of lowlands, pasture, farmland, and some rural roads in Mason Valley. Preventative sandbagging of lowest homes in Mason and Yearington should be done as river rises, but little flooding occurs. There may be some minor flooding of yards and basements in Mason. About 2250. Like flood of July 4, 1980. Chance of exceeding this flow any year about 1 in 7 per USGS esstimate.
10.8 FeetMinor to moderate flooding of lowlands, pasture, and farmland adjacent to the river throughout the Mason Valley-Yerington area. Some rural roads flood. Preventative sandbagging of low structures in Mason and Yerington is necessary as river rises, but little flooding occurs. Some minor flooding of basements and yards in Mason. Possible damage to irrigation structures. About 2450 cfs. Like floods of July 1, 2011 and May 18, 1996. Chance of exceeding this flow about a 1 in 8 any year per USGS estimate.
11.0 FeetModerate flooding of lowlands, pasture, and farmland adjacent to river throughout Mason Valley-Yerington area. Several rural and some secondary public roads flood. Yards and basements of lowest homes adjacent to the river in Mason and Yerington begin flooding, preventative sandbagging is necessary. Possible damage to irrigation structures and levees. About 2600 cfs. Higher than July 1, 2011 but lower than June 19, 1983 floods. Chance of exceeding this flow about a 1 in 9 any year per USGS estimate.
11.3 FeetModerate flooding of lowlands with damage to farm and pasture lands throughout the Mason Valley-Yerington area. Some low structures adjacent to river have flood damage. Levee and diversion structure failures are possible. Several secondary and some primary roads flood. About 2800 cfs. Like floods of July 11, 1995 and June 19, 1983. Chance of exceeding this flow about 1 in 10 any year per USGS estimate.
11.6 FeetMajor flooding of lowlands with significant damage to farm and pasture lands throughout the Mason Valley-Yerington area. Structures adjacent to river in floodplain have damage if not sandbagged. Many levees leaking and failures are possible. Diversion dam north of Yerington in danger of failure. Flooding of many secondary and some primary roads occurs. About 3000 cfs. Like flood of July 11, 1995. USGS estimates this flow has about a 1 in 15 chance of being exceeded any year.
12.0 FeetMajor flooding in Mason Valley-Yerington area. Many homes, businesses, structures, roads, bridges, and well over 1000 acres of farm and pasture land near the river floods. Some portions of Yerington flood. About 3300 cfs exceeds flood of July 11, 1995 but not as severe as record flood of January 4, 1997. USGS esstimates that this much flow has about a 1 in 20 chance of being exceeded any year.
12.5 FeetNear record flooding the Mason Valley-Yerington area. Homes, businesses, farmland, pasture, roads, bridges, and structures in the floodplain are flooded. At about 3700 cfs, about like record flood of January 4, 1997 (estimated 3900 cfs), which flooded over 3000 acres in the Yerington area with over 500 businesses and homes affected. Central Yerington and airport were not flooded in 1997. USGS estimates that this much flow has about a 1 in 25 chance of being exceeded any year.
13.0 FeetRecord flood disaster in the Mason Valley-Yerington area. Numerous homes, businesses, structures, roads, bridges, and over 4000 acres of farmland and pasture land are flooded with major damage. At about 4150 cfs, worse than record flood of January 4, 1997 that flooded over 3000 acres in the Yerington area with over 500 businesses and homes affected. USGS estimates that this much flow has about a 1 in 35 chance of being exceeded in any year.
Product Disclaimer

This river graphic is not intended to serve as a substitute for official flood watches, warnings, advisories, or statements issued by the NWS Reno Weather Forecast Office. Observations are preliminary and subject to change. River levels identified as "forecast" should be consistent with those contained in official NWS products. River levels identified as "guidance" have significant uncertainty due to future weather or reservoir regulation and are provided for planning purposes only.