Travelers should expect more frequent lifts of the Interstate Bridge in the days ahead because recent rains have increased the level of the Columbia River.
The river level at the Interstate Bridge is generally about six feet. This week the river level at the bridge exceeded 15 feet, which is still below the flood level of 18 feet.
The increased river level has reduced the clearance at the high span, which is at the hump in the bridge at mid-river. That causes more marine traffic to use the lift span along the north side the river.
Usually, the bridge averages one or two lifts a week for marine traffic. This week the bridge has averaged two or three lifts a day. The average lift time is 15 to 20 minutes.
More lifts mean more delays on I-5.
Under maritime law, marine traffic has priority over I-5 highway traffic. However, no lifts are allowed during the morning and evening commutes times, from 6:30 a.m. to 9 a.m. and again from 2:30 p.m. to 6 p.m. most weekdays.
Factors that contribute to the high water include rainfall and warm temperatures that increase snowmelt, the Columbia River dams and their ability to regulate river volume and, to a lesser extent, the tides.
The Columbia River reached the flood stage at the Interstate Bridge in 2017, when it reached 18 feet, and in 2011 when it reached 19 feet. The highest level in recent years came in 1996 when the river reached 24 feet.
The Interstate Bridge is jointly owned by Oregon and Washington and is operated and maintained by ODOT. The northbound span opened Feb. 14, 1917 and the southbound span July 1, 1958.
Source: ODOT