FLOOD POTENTIAL IN THE EASTERN GREAT BASIN

The following are generalized discussions of the flood potential due to snowmelt in the Eastern Great Basin drainage as of April 1, 1997. Discussions are segregated by state. It is important to understand that the potential for flooding may increase dramatically if snowmelt accelerates rapidly due to above normal temperatures or if significant rain events occur.

UTAH: The flood potential for the Great Basin of northern Utah remains high at this time . Although the snowpack percent of average values are lower than those of early March, a very large mountain snowpack exists. As of April 1, the snowpack was 90-180 percent of average. Forecast procedures indicate peak flows will exceed floood levels on the Logan River. Forecast procedures and flood levels do no exist for all rivers, however bankfull conditions are likely on most northern Utah streams with over-bank flow still a strong possibility. This is especially true for the Bear and Weber River drainages where the largest snowpack exists.

Much of the lower and middle elevation snowpack was depleted in the southern Great Basin during March. As of April 1, snowpack was below or near average for all areas with the exception of the Beaver River drainage. High flows are likely along the Beaver River with some over-bank flows possible. Elsewhere in the Great Basin of southern Utah, flood related problems due solely to snowmelt are not anticipated.

IDAHO: The potential for snowmelt flooding in the Great Basin within Idaho remains high at this time. A very large snowpack exists within the Bear River Basin with 120-150 percent of average at many mountain locations. Although flood levels and forecast procedures do no exist for specific sites, high flows near bankfull are expected along the Bear and its tributaries this spring.