The suspension is effective immediately.
"I am extremely disappointed to announce that today I have accepted a penalty under MLB's Joint Drug Treatment and Prevention Program," Powell said in a statement released through the Major League Baseball Players Association. "While I realize this has become a common refrain among athletes faced with such discipline, the truth is I do not know how this substance could possibly have been in my system. I can only say that this is not a reflection of my true character, and those who know me understand the deep respect I have for my fellow competitors and teammates. I would never betray that by attempting to gain an improper advantage.
"I have already taken proactive steps to look into this situation, and will not rest until there is a full explanation for this result which will vindicate me. Until that happens, however, I realize that accountability rests solely with me on this matter. I am responsible for everything I put in my body, and part of that responsibility means dealing with the consequences regardless of the explanation.
"I would like to apologize to my family, friends, the Seattle Mariners organization and its fans for this situation, and I will work to rebuild trust with each of you through my words and actions moving forward. I promise you, I will find a solution to all of this."
Powell tested positive for dehydrochlormethyltestosterone, an anabolic steroid, in violation of Major League Baseball's Joint Drug Prevention and Treatment Program.
This is the second time Powell has been suspended. He also drew a 50-game suspension in 2014 under the Minor League Drug Prevention and Treatment program after testing positive for an amphetamine while with the A's organization.
The Mariners issued the following statement:
"The Seattle Mariners are disappointed that Boog Powell has violated the terms of Major League Baseball's Joint Drug Prevention and Treatment Program. Our organization fully supports the program and its efforts to eliminate performance-enhancing substances from our game. Per the Basic Agreement, the Mariners will have no further comment."
Greg Johns has covered the Mariners since 1997, and for MLB.com since 2011. Follow him on Twitter @GregJohnsMLB and listen to his podcast. This story was not subject to the approval of Major League Baseball or its clubs.