| Flood Impacts |
| 10.5 | FLOOD DISASTER FROM WALKER RIVER CYN TO TOPAZ LAKE IN ANTELOPE VALLEY...IN SMITH VALLEY/WELLINGTON AREA...AND IN MASON VALLEY YERINGTON AREA. WIDESPREAD FLOOD DAMAGE TO ROADS...BRIDGES...HOMES AND STRUCTURES ALONG RIVER. SEVERE DAMAGE TO US 395 IN WALKER CYN...AND NV HWY 208 IN SMITH VALLEY-WILSON CYN...THESE HIGHWAYS PROBABLY CLOSED. EST. FLOW 8000 CFS...ABOUT A 100-YEAR RETURN PERIOD. HISTORICALLY...THIS FLOW HAS BEEN REACHED OR EXCEEDED ONLY ONCE...IN JAN 1997 (12,500 CFS). |
| 10.0 | FLOOD DISASTER FROM WALKER RIVER CYN TO TOPAZ LAKE IN ANTELOPE VALLEY...IN SMITH VALLEY/WELLINGTON AREA...AND IN MASON VALLEY YERINGTON AREA. WIDESPREAD FLOOD DAMAGE TO ROADS...BRIDGES...HOMES AND STRUCTURES ALONG RIVER. SEVERE DAMAGE TO US 395 IN WALKER CYN...AND NV HWY 208 IN SMITH VALLEY-WILSON CYN...THESE HIGHWAYS MAY BE CLOSED. EST. FLOW 6800 CFS...ABOUT A 75-YEAR RETURN PERIOD. HISTORICALLY...THIS FLOW HAS BEEN REACHED OR EXCEEDED ONLY TWICE...IN DEC 1937 AND JAN 1997. |
| 9.5 | MAJOR FLOODING FROM WALKER RIVER CYN TO TOPAZ LAKE IN ANTELOPE VALLEY...IN SMITH VALLEY/WELLINGTON AREA...AND IN MASON VALLEY YERINGTON AREA. WIDESPREAD FLOODING OF LOWLANDS...ROADS...BRIDGES...HOMES AND STRUCTURES ALONG RIVER. TRANSPORTATION AFFECTED WITH DAMAGE TO US 395 IN WALKER CYN...AND NV HWY 208 IN SMITH VALLEY-WILSON CYN. EST. FLOW 5600 CFS...ABOUT A 40-YEAR RETURN PERIOD. HISTORICALLY...THIS FLOW HAS BEEN EXCEEDED ONLY THREE TIMES...IN DEC 1937...NOV 1950 AND JAN 1997 FLOODS. |
| 9.0 | MODERATE TO SIGNIFICANT FLOODING OF LOWLAND...PASTURE...RURAL ROADS...SOME YARDS AND BASEMENTS ALONG RIVER IN ANTELOPE AND SMITH VALLEYS. FLOODING OF STRUCTURES LIMITED IN ANTELOPE AND SMITH VALLEYS...THOUGH SANDBAGGING IS NECESSARY. HOWEVER...IN MASON VALLEY/YERINGTON AREA...FLOODING OF STRUCTURES IS SIGNIFICANT. IN JULY 1995...SEVERAL HOMES...BUSINESSES AND 1000S OF ACRES OF FARMLAND IN MASON VALLEY WERE FLOODED...WITH LEVEES OVERTOPPED. 4600 CFS...ABOUT A 4 CHANCE ANY YEAR...25-YEAR RETURN PERIOD. |
| 8.5 | FLOOD STAGE. MINOR FLOODING OF LOWLANDS...PASTURE AND SOME RURAL ROADS ALONG RIVER FROM WALKER TO TOPAZ LAKE CA. HOWEVER...NOTE THAT FLOWS AT THIS STAGE (3800 TO 4000 CFS) WILL CAUSE MODERATE FLOODING ON LOWER WEST WALKER (WELLINGTON/SMITH AREA) AND MAINSTEM WALKER (MASON VALLEY/YERINGTON AREA). SOME SANDBAGGING OF STRUCTURES WILL LIKELY BE NECESSARY IN THE MASON/YERINGTON AREA. ABOUT 3800 CFS...A 10% CHANCE ANY (10 YEAR RETURN PERIOD). |
| 8.0 | SOME MINOR FLOODING OF LOWLANDS...PASTURE AND RURAL ROADS. ABOUT 3000 CFS...A 15% CHANCE ANY YEAR (ABOUT 7-YEAR RETURN PERIOD). MAXIMUM DIVERSION TO TOPAZ LAKE IS ABOUT 1300 CFS...REMAINDER GOES DOWN THE WEST WALKER TO WELLINGTON/SMITH VALLEY. IF TOPAZ IS RELEASING...FLOW AT WELLINGTON WILL BE TOPAZ RELEASE PLUS AMOUNT GOING DOWN WEST WALKER BELOW TOPAZ DIVERSION. |
| 7.5 | MONITORING STAGE, NO FLOODING. 2400 CFS...ABOUT A 20% CHANCE ANY YEAR (5-YEAR RETURN PERIOD). NOTE THAT MAXIMUM DIVERSION TO TOPAZ LAKE IS ABOUT 1300 CFS...REMAINDER GOES DOWN WEST WALKER TO WELLINGTON/SMITH VALLEY. IF TOPAZ IS RELEASING...FLOW AT WELLINGTON WILL BE TOPAZ RELEASE PLUS AMOUNT GOING DOWN WEST WALKER BELOW TOPAZ DIVERSION. |
