CNRFC - Hydrology - River Guidance - Graphical RVF

WALKER RIVER - MASON AT SNYDER LANE (MASN2)

Latitude: 38.92º N	Longitude: 119.19º W	Elevation: 4420 Feet
Location: Lyon County in Nevada		River Group: Eastern Sierra

Issuance Time:

Mar 31 2023 at 1:49 PM PDT

Next Issuance:

Apr 01 2023 at 9:00 AM PDT

Monitor Stage: 9.0 Feet

Flood Stage: 9.8 Feet

Please Note:

Significant losses can occur in the Mason Valley upstream of the Mason stream gage. Increased forecast uncertainty exists in the long range forecast due to these unknown losses.

Plot Type:

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

Historical Stage/Flow Data
Water Year	Peak Discharge (cfs)	Stage (feet)	Date
Most Recent 5 Years
2021*	316	5.48	May 11, 2021
2020*	335	5.62	Oct 8, 2019
2019*	2,250	9.74	Jun 16, 2019
2018*	1,410	8.55	May 27, 2018
2017*	2,910	10.94	Jun 24, 2017
Historical High Stage/Flow Events (Period of Record - April 1974 to Present)** - Ranked by Flow
1997*	3,900***	12.72	Jan 04, 1997
2017*	2,910	10.94	Jun 24, 2017
1995*	2,980****	11.57	Jul 11, 1995
1983*	2,790***	11.31	Jun 19, 1983
2011*	2,420	10.77	Jul 01, 2011
* Discharge affected by regulation or diversion.
** Break in data between Oct 1984 and Sept 2010.
*** Prior to Sep 30, 1984 - gage location 0.1 mile downstream at different datum.
**** Estimated using other gages and MASN2 rating #5.1

Location Photographs
Upstream Photo	Gage House Photo	Downstream Photo

ESRI™ Locator Map

Official 7 Day National Weather Service Forecast (NVZ001)

Today: Partly cloudy. Highs 55 to 65. Southwest winds 10 to 15 mph. Gusts up to 40 mph in the afternoon.

Tonight: Partly cloudy in the evening then becoming clear. Lows 29 to 39. West winds 10 to 20 mph with gusts up to 35 mph.

Sunday: Sunny. Areas of blowing dust in the afternoon. Highs 54 to 64. Southwest winds around 10 mph with gusts up to 30 mph increasing to west 15 to 20 mph with gusts up to 45 mph in the afternoon.

Sunday Night: Areas of blowing dust in the evening. Clear in the evening, then mostly cloudy with a slight chance of snow showers after midnight. Snow level 6000 feet lowering to the valley floor. Lows 23 to 33. West winds 20 to 30 mph. Gusts up to 50 mph decreasing to 35 mph after midnight.

Monday: Mostly cloudy with a chance of snow showers. Highs 32 to 42. Northwest winds 20 to 30 mph with gusts up to 55 mph.

Monday Night: Windy. Mostly cloudy in the evening then becoming partly cloudy. Lows 20 to 30.

Tuesday: Partly cloudy. Highs 37 to 47.

Tuesday Night: Mostly cloudy. Lows 20 to 30.

Wednesday and Wednesday Night: Partly cloudy. Highs 41 to 51. Lows 24 to 34.

Thursday and Thursday Night: Partly cloudy with a slight chance of snow showers. Highs 46 to 56. Lows 26 to 36.

Friday: Partly cloudy. Slight chance of snow showers in the afternoon. Highs 51 to 61.

Impacts - E19 Information
9.0 Feet	Monitor Stage, near bankfull conditions. No flooding in the Mason Valley-Yerington area.
9.8 Feet	Flood Stage. Minor lowland flooding begins throughout Mason Valley-Yerington area with some inundation of lowlands and rural roads.
10.0 Feet	Minor flooding of lowlands, pasture, cropland, and some rural roads throughout the Mason Valley-Yerington area. No flooding of structures of roads.
10.3 Feet	Minor 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. Some flooding of rural roads.
10.5 Feet	Minor flooding of lowlands, pasture, farmland, and some rural roads in Mason Valley. Preventative sandbagging of lowest homes in Mason and Yerington should be done as river rises, but limited flooding occurs. There may be some minor flooding of yards and basements in Mason.
10.8 Feet	Minor 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 may be necessary as river rises, but limited flooding occurs. Some minor flooding of basements and yards in Mason. Similar level to floods of July 1, 2011.
11.0 Feet	Moderate 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. Similar to June 24, 2017 peak, and slightly higher than July 1, 2011 peak.
11.3 Feet	Moderate flooding of lowlands, farm, and pasture lands throughout the Mason Valley-Yerington area. Some low structures adjacent to river begin to flood. Several secondary and some primary roads flood. Exceeds flood peak of June 2017.
11.6 Feet	Major flooding of lowlands throughout the Mason Valley-Yerington area. Structures adjacent to river in floodplain may be damaged if not protected. Flooding of many secondary and some primary roads occurs.
12.0 Feet	Major flooding in the Mason Valley-Yerington area. Some portions of Yerington flood if breaches develop and the river spreads east. Many roads flood. Extensive flooding of farmland and pasture near the river flood.
12.5 Feet	Major flooding in the Mason Valley-Yerington area. Extensive flooding of farm and pasture lands. Many roads flooded. Some portions of Yerington flooded if breaches develop and the river spreads east.
13.0 Feet	Near-record flooding in the Mason Valley-Yerington area. Significant flooding of homes and businesses in Yerington possible if breaches develop and the river spreads east. Extensive flooding of agricultural lands likely. Many primary and secondary roads flooded.

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.

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