This included the stabbing incident in May, with three staff also physically assaulted.
A DHB spokesperson said the stabbed staff member was "treated for injuries at the time, received support and has returned to work". Internal reviews are ongoing.
Patients turning up in ED can have many different and complex conditions or behavioural issues, and a mental health assessment team is available 24/7.
"A number of services across the organisation work collaboratively to ensure people who present with behavioural disturbances are cared for to the highest standards, whether due to underlying physical ill health, mental health or a combination of both," the spokesperson said in a statement.
"The assessments and medical records help determine whether it is medically safe for a patient to go to a ward for continued assessments/treatments and care. This could include a general or mental health ward, as well as discharge, and will include safety arrangements - either in the community or wards."
In the same report, the division of mental health and addictions said there had been a big increase in referrals after the end of the Covid-19 lockdown, with the biggest increase from ED and most patients being female.
"We expect this trend will continue as people begin to grapple with their new reality post-Covid-19, with job losses and adjusting to a new norm."
Already under-pressure child and adolescent mental health services had experienced the same post-lockdown surge, the report noted, as schools and GPs reopened.
The service expects a sustained increase in referrals relating to a range of social-economic factors with parents becoming unemployed resulting in financial strains/stressors taking a toll on overall wellbeing and mental stamina, limited capacity to cope with post-Covid-19 new norms and care and protection issues as a result of family violence and complex family dynamics."