Watershed Information System

An online tool to efficiently organise, store and provide access to watershed information for collective water action

Watershed and river

Maps Images References

The Lower Boise Watershed


Basic Information

USGS Water Resources Region and sub-region

17 - Pacific Northwest - sub-region 1705 (See sub-region layer in map)

Hydrological unit code 17050114
Length 64 river miles
Flows from
Mouth of the Lucky Peak Reservoir (east)
Delivers to
Confluence with the Snake River near Parma (west)
Main tributaries Indian creek, Fifteenmile creek, Willow creek (See Rivers layer in map)
Size 70 by 35 miles (110 by 55 km)
Area 850233 acres / 3440 sq. Km.


Key messages:

  • The Lower Boise is hydrologically independent from the main Snake River. It has a long flood plain with important agricultural activity, which depends on irrigation water provided by the Lucky Peak dam.
  • average annual precipitation in the Lower Boise is 10 inches (BREN, 2015). (Check updated climatic data in Water info system layer in the map at Water Balance section)
  • Elevations range from 6,994 feet in the north-east of the watershed to 2,180 feet at the basin outlet (See Google satellite Image in the map to see topography).
  • The majority of the watershed overlays politically with counties Canyon (county seat: Caldwell) and Ada (county seat: Boise). Population’s estimations for these two counties combined are 629,379 people in 2014; 809,100 people in 2030 and 1.57 million by 2065 (an increase of 250% with respect to 2014) (SPF Water, 2016).


Watershed Boundary Dataset Map


  • USGS-National Hydrography - Watershed Boundary Dataset - link
  • Water Resources Region 17: Pacific Northwest. Sub-region 1705: Middle Snake - link
  • USDA - Geospatial Data Gateway - link
  • USGS - National Water Information System - link
  • Boise River Enhancement Network (BREN) - link