Data prior to 2018 can be found here > OASIS Notices:  

Recent notifications can be found on OASIS (above), as well as on the MISO website:

Recorded in the monthly ROWG report, which is posted in a closed meeting -- can be found here:

Presentations on Maximum Generation Events can be found in various stakeholder meeting materials (ie: MSC, RSC, ROWG, Markets Committee of the Board of Directors, etc.)