The Seattle Times first reported Portis' arrest Monday.
Portis was pulled over on May 5 for allegedly speeding when a Washington State Patrol officer reported noticing "a strong odor of intoxicants coming from the vehicle" and that the driver "had watery bloodshoot eyes." In the arrest report obtained by NFL.com, the officer stated Portis admitted to drinking tequila earlier. When asked what day it was, Portis told the trooper "Cinco de Mayo."
Portis later submitted to two breath tests and registered blood alcohol concentration readings of 0.092 and 0.078, according to the police report. The legal limit in Washington state is 0.08.
Portis was re-signed by the Seahawks in April to a two-year contract with a base salary of $480,000 in 2013 and expected to compete with Brady Quinn and Jerrod Johnson for the backup job behind Russell Wilson.
Portis, 25, has yet to play in a regular-season NFL game.