The vertical plane of reference in the Columbia River estuary from the Mouth to Harrington Point is mean lower low water, then adopted low water upstream to Portland and Vancouver. Tidal range at the Mouth of the Columbia River is about 8 feet, and at Portland and Vancouver, about 3 feet during low river stages. Extreme tidal ranges are about 13 and 3 feet, respectively. Annual freshets have little effect on stage of tide at the Mouth of the Columbia River; at Portland and Vancouver, they average about 12 feet, while the highest known reached a stage of 33 feet at Portland.

The majority of shoaling in the Columbia River occurs during the period immediately following the annual freshet in early summer. Dredges are brought in to remove shoals before low water levels in the fall. Many shoals in the Columbia River are called sand waves, which look like giant versions of sand ripples that form as waves recede at the beach. Sand waves along the bottom of the Columbia River are often 6 to 12 feet high, up to 500 feet long, and can move downstream at a rate of 20 feet per day during high flows.

In some river reaches, dredges remove up to 5 feet of advanced maintenance dredging below the authorized channel depth prior to the annual freshet so that shoaling builds below authorized depth and does not restrict commercial vessel traffic. Advanced maintenance width dredging is also practiced up to 100 feet outside the authorized channel width in locations where heavy shoals encroach from the sides. During the past 2 years, minimum maintenance dredging has averaged 7 million cubic yards per year. Dredged material is placed in-water, upland, and along shorelines, including many beneficial use sites. Commercial vessel movement is timed with tidal fluctuations to maximize the loaded draft and economic benefits of the navigation channel.

Authorized channel 43 feet deep and generally 600 feet wide from Mouth of Columbia River, Columbia River Mile 3 to Vancouver, Wash., CRM 105.5.

Construction was completed in November 2010. Channel between the Willamette River confluence, CRM 101.4 and the Lower Turning Basin at Vancouver, Wash., CRM 104.6 is limited to 500 feet in width until need for additional width is demonstrated by developed traffic.

Turning basins are at: Astoria, Ore., CRM 13 (43 feet deep); Longview, Wash., CRM 66.5 (40 feet deep); Kalama, Wash., CRM 73.5 (43 feet deep); and Lower Vancouver, Wash., CRM 105.5 (43 feet deep).

The channel is 43 feet deep and 400 feet wide from the Columbia River CRM 102 to Oregon Slough, River Mile 1.5. The channel is 35 feet deep and 500 feet wide from CRM 105.5 to 106.5, the distance between existing railroad and highway bridges. The Upper Turning basin at Vancouver, Wash., CRM 106.5, is 35 feet deep.

The authorized channel is 43 feet deep, width varying, from the Columbia River, Willamette River Mile 0, to the Broadway Bridge in Portland, Ore., WRM 11.6.

Construction has been deferred until after resolution of cleanup issues associated with the Willamette River being named to the federal National Priorities List by USEPA under the Comprehensive Environmental Response, Compensation, and Liability Act.

Channel maintenance continues at 40 feet deep, with authorized turning basins at WRM 4, WRM 10 (Albina) and WRM 11.6 (43 feet deep).

• Channel for access to Hammond Boat Basin, 10 feet deep and 100 feet wide from deep water in the Columbia River, at approximately CRM 8.5, into and across the full boat basin.
• Channel 34 feet deep and 350 feet wide from the Columbia River, at approximately CRM 18.5, to the existing piers at Tongue Point. Turning basin 25 feet deep.
• Channel 10 feet deep and 300 feet wide from the Columbia River, at approximately CRM 37.5 to Cathlamet, Wash.
• Channel 9 feet deep and 200 feet wide for the Wahkiakum Ferry crossing between the Columbia River Channel and Puget Island, across from the authorized Westport Slough project, at approximately CRM 43.
• Channel is from the Columbia River Channel below Mount Coffin, at approximately CRM 63.5, upstream past Weyerhaeuser Timber Co. plant, along the pier head line to the Port of Longview dock, the downstream 2,400 feet of this channel--authorized to be 30 feet deep and 300 feet wide, and remainder to be 28 feet deep and 250 feet wide.
• Channel is 24 feet deep and 200 feet wide along frontage of town of Rainier, Ore., connected at both downstream and upstream ends to deep water in Columbia River, at approximately CRM 65.5 to CRM 67.5.
• Channel is 8 feet deep and 150 feet wide from this depth in Columbia River, approx. CRM 67.5 through the Old Mouth of the Cowlitz River, WA to a point about 3,000 feet upstream from the present terminus of the harbor line.
• Channel is 30 feet deep and 300 feet wide at St. Helens, OR between the Columbia River Channel downstream of Sand Island, approx. CRM 84.5 and the town of St. Helens at the mouth of the Multnomah Channel, previously Willamette Slough.
• Channel is 30 feet deep and 500 feet wide connecting the St. Helens Channel with the Columbia River Channel upstream of Sand Island, at approximately CRM 87.

• Anchorages, 43 feet deep and 25 feet deep, with stern anchor buoys, at Vancouver, Wash., CRM 103.
• Stern anchor buoys, at Rainier, Ore., CRM 67, Prescott, Ore., CRM 72 and Vancouver, Wash., CRM 100.

• Small boat basin improvement at Hammond, Ore., at approximately CRM 8.5. Rebuilt west breakwater and constructed rubblemound east breakwater and groin.
• Small boat mooring basin constructed at Astoria, Ore., at approximately CRM 16. Constructed sheet pile, sand-filled breakwater about 2,400 feet long with a 30 feet roadway along its full length, and steel pile shore wings totaling about 1,460 feet long and for stone-and-pile dikes and revetments.

• Webb wildlife mitigation site, Ore., at approximately CRM 47. Construction and maintenance of a wetland area and two grass fields which provide year-round habitat for waterfowl.
• Cottonwood wildlife mitigation site, Wash., at approximately CRM 70. Construction and maintenance of a riparian forest and improved wetland areas which support species like Columbia white-tailed deer.
• Chumbley wildlife mitigation site, Wash., at approximately CRM 81. Construction and maintenance of riparian forest.

The Rivers and Harbors acts of: June 18, 1878, July 13, 1892, June 3, 1896, June 13, 1902, March 3, 1905, Feb. 27, 1911, July 25,1912, July 27, 1916, Aug. 8, 1917, Sept. 22, 1922, March 4, 1923, March 3, 1925, March 3, 1927, July 3, 1930, Sept. 6, 1933, Aug. 30, 1935, Aug. 26, 1937, March 2, 1945, July 24, 1946, and Oct. 23, 1962.

Section 107 of the Rivers and Harbors Act of 1960 provides authority for the Corps of Engineers to develop and construct small navigation projects. Small Columbia River navigation projects authorized under Section 107 were approved in May 1975, July 1975, Feb. 1986, July 1989, Sept. 1993, Oct. 1993, and Aug. 3, 2011.

The Water Resources Development acts of Oct. 12, 1996, and Aug. 17, 1999, and the Consolidated Appropriations Act of Jan. 23, 2004.