US Army Corps of Engineers
Walla Walla District
Oregon, Washington, and Idaho
CONDITION OF IMPROVEMENT: 30 September 1994
PWI NUMBER: None
- Navigation: A navigation channel was authorized for the Snake River (photo) from its mouth near Pasco, Washington (confluence with Columbia River), to Johnson Bar downstream of Hell's Canyon Dam (within the Hell's Canyon National Recreation Area).
The River and Harbor Act of 1902 (Public Law 57-154,
57th Congress, 1st Session), in accordance with House Document Number 127 (Examination and Survey of Snake River, Idaho and Washington, dated December 1, 1990), 56th Congress, 2d session), authorized the completion of an improvement for the maintenance of the Snake River between Riparia (River Mile 67) and Lewiston, Idaho; and improvements between Lewiston and Pittsburg Landing.
The River and Harbor Act of 1910 (Public Law 61-264, 61st Congress, approved June 25, 1910) authorized channel improvements from the mouth of the Snake River to Riparia.
The River and Harbor Act of 1935 (Public Law 74-409, 74th Congress, 1st session, approved August 30, 1935) under Columbia and Snake Rivers, Oregon, Washington, and Idaho, and as specified in River and Harbors Committee Documents Number 25 (72d Congress) and Number 16 (73d Congress), authorized the extension of the navigation improvements from Pittsburg landing to Johnson Bar.
- Lower Snake River Dams: The four Snake River dams were authorized by Section 2 of the River and Harbor Act of 1945 (Public Law 79-14, 79th Congress, 1st Session), and were approved March 2, 1945. This Act authorized the construction of any necessary dams and open channel improvements for the purpose of providing slack water navigation and irrigation in accordance with House Document 704, 74th Congress, 3d Session. The Act also specifies that all surplus electrical power be delivered to the Secretary of the Interior. A report, Special
Report on Selection of Sites, Lower Snake River, Oregon, Washington, and Idaho, dated March 14, 1947, was prepared by the Corps, Portland District. The report recommended four dams with overlapping
lakes as optimum development for this reach of the river. Later reports confirmed the proposal for four dams. The location of each individual project is shown on the accompanying map.
The Corps was authorized to construct, maintain, and operate public parks and recreation facilities; and allow recreational usage of the water areas in Section 4 of The River and Harbor Act of 1944 (Public Law 78-534, 78th Congress, 2d Session), as amended.
LOCAL COOPERATION: None required.
- Navigation from Pasco, Washington, to Lewiston, Idaho: With the construction of the four dams on the lower Snake River, navigation has greatly improved. However, certain areas need to
be maintain between Pasco, Washington, and Lewiston, Idaho. Channel dredging was done between 1977 and 1984 downstream of Ice Harbor Dam. Three maintenance dredging contracts, in 1982, 1986, and 1987,
cleared sediment at the confluence of the Snake and Clearwater Rivers. A navigation channel, 250 feet wide and 14 feet deep, is provided from the mouth of the Snake River to the confluence of the Snake and
- Navigation Channel from Lewiston, Idaho to Johnson Bar: A navigation channel is maintained in the Snake River from Lewiston to Johnson Bar Landing. There has also been extended channel improvement form Pittsburg Landing to Johnson Bar Landing. Under the aforementioned authorizations, channel depth was to be 5 feet from the mouth to Lewiston, with no specified depth from Lewiston to Johnson Bar Landing. Channel width was to be 60 feet from Riparia to Lewiston, with
no specified width from the mouth of the Snake River to Riparia, or from Lewiston to Johnson Bar Landing. The navigation depth is about 2.7 feet from Lewiston to Johnson Bar Landing.
- Lower Snake River Dams: Although authorized under the Snake River Project, the Corps originally referred to this series of dams as the "Lower Snake River Project." In general, the Corps regards these four projects as separate entities for funding purposes. The four units start at the confluence of the Columbia River end of the slackwater at Lake Wallula. Moving upstream from there, the four projects are:
- Ice Harbor/Lake Sacajawea;
- Lower Monumental/Lake West;
- Little Goose/Lake Bryan; and
- Lower Granite/Lower Granite Lake.
- Navigation from Pasco, Washington, to Lewiston, Idaho: Channel dredging was done between 1977 and 1984 downstream of Ice Harbor Dam. Three maintenance dredging contracts, in 1982, 1986, and 1987, cleared sediment at the confluence of the Snake and Clearwater Rivers.
- Lower Snake River Dams:
- Navigation Channel from Lewiston, Idaho, to Johnson Bar.
COST: Open river channel maintenance costs from Pasco, Washington, to Lewiston, Idaho, have amounted to $186,570. The cost of channel maintenance from Lewiston to Johnson Bar Landing has
been $34,613 for new work, and $393,202 for operation and maintenance. Individual multi-purpose project costs, from the mouth of the Snake River to Lewiston, are detailed in the appropriate text.
Last Updated: 11:36 17.03.98