November 27, 2025, Seward Folly Staff

The Lowell Creek Diversion Tunnel has long served as Seward’s primary defense against flooding, an engineering milestone dating back to the era of President Franklin D. Roosevelt. Last Thursday, around 50 residents gathered at the local library to reflect on the city’s 85-year effort to control Lowell Creek and to hear about plans for a major update. A new, significantly larger tunnel is slated for construction from 2027 through 2031.

The city of Seward sits on the outwash of Lowell Creek

Colleen Kelly of the Resurrection Bay Historical Society began the event with a look at Seward’s flood-prone past. The city itself owes much to the water and gravel that have shaped its landscape for centuries. The town is built upon the creek’s flooding events that have accumulated over millennia. Early attempts to harness Lowell Creek in 1904 failed to outpace nature’s force. Major floods in 1917 and 1923 caused extensive damage, including the destruction of buildings and the sweeping away of St. Xavier’s Hospital. In 1928, the city invested the equivalent of $2.4 million today to build a large wooden flume, which was destroyed within months by another flood.

Lowell Creek flooding causing havoc in Seward in 1917, as recorded in The Seward Gateway

The city tried again in 1935 with a larger flume, but it too succumbed to the creek. Finally, in the lead-up to World War II, the Army Corps of Engineers intervened, drilling a 2,000-foot tunnel through Bear Mountain. It took them about a year to finish the massive project, with 2 and then 3 shifts a day through the winter. Completed in 1940, the tunnel has protected Seward ever since, withstanding even the 1964 earthquake and several major floods. Recent images from the 2018 flood, however, underscored the creek’s ongoing threat and the limitations of the aging infrastructure.

The existing tunnel has been repaired many times. This photo shows recent repairs inside the concrete structure.

Big changes are ahead. At last week’s meeting, public works director Doug Schoessler outlined plans for the new tunnel, joined by a project manager from the United States Army Corps of Engineers (USACE). The proposed tunnel will span 18 feet, nearly twice the width of the current structure, and feature a granite floor to handle debris. Staff from USACE Alaska District recently toured the inner workings of the Pfaffensprung sediment bypass tunnel in Switzerland, which is part of a dam that impounds the River Reuss. This system has been in use for over 100 years and has employed granite pavers in the lining of its tunnel because, when compared with other materials, granite is considered to be more resilient. The creek’s existing lining is iron rails embedded in concrete.

The new tunnel’s capacity will reach 8,400 cubic feet per second, almost triple that of the existing tunnel. Three hundred concrete-filled bore holes will anchor its entrance, and the original tunnel will serve as a backup. In addition, the outflow will have a concrete bridge over the existing road, with the spillway on the ocean side. 

This photo shows the existing tunnel after the latest upgrades.

The estimated cost of the new project is a massive $400 million, with federal funding covering most expenses. Seward’s primary responsibilities will include relocating roads and utilities and collaborating with Pacific Seafoods to move its plant to the other side of the bay, allowing tunnel debris to be used as infill along the old site – which, as Schoessler emphasized, will dramatically help with the efficiency of the project. Initial plans to repave 3rd Avenue after construction have since been dropped.

As Seward moves forward with the new project, it hopes to keep Lowell Creek in check, knowing from experience that the creek will pose its own challenges.