The St. Patrick's Day party on Ezra Avenue was the largest ever, despite an increase in police presence and expenditures to crack down on the celebrations.

Waterloo Regional Police Service told CBC News in an interview Monday morning that at its peak attendance, there were 22,400 people partying.

That is more than the population of Owen Sound.

'30 to 300 people at each residence'

And it's not even the total amount of people who attended, but instead a snapshot of the amount of people in the Ezra Avenue corridor during the busiest time of the day, said WRPS communications officer Cherri Greeno.

The estimate also does not take into account people inside houses, on surrounding streets or in backyards.

Around 2 p.m., on Saturday, Inspector Michael Haffner said officers had attended about 30 gatherings in the area of Ezra Avenue, Albert and Marshall streets, and found between 30 to 300 people at each residence.

Hundreds of students congregate at the house as <a href="https://twitter.com/citywaterloo?ref_src=twsrc%5Etfw">@citywaterloo</a> <a href="https://twitter.com/WRPSToday?ref_src=twsrc%5Etfw">@WRPSToday</a> <a href="https://twitter.com/ROWPublicHealth?ref_src=twsrc%5Etfw">@ROWPublicHealth</a> watch on <a href="https://twitter.com/hashtag/ezra?src=hash&ref_src=twsrc%5Etfw">#ezra</a>. <a href="https://twitter.com/CBCKW891?ref_src=twsrc%5Etfw">@CBCKW891</a> <a href="https://t.co/vCyRxvoIyG">pic.twitter.com/vCyRxvoIyG</a> —@PaviaJoe1964

​Police lay over 600 charges

Greeno said officers responded to 248 calls for service between 8 a.m. Saturday to 6 a.m. Sunday.

As a result, police laid 619 charges:

Highway Traffic Act (62),

Liquor Licence Act (435),

Criminal Code (18),

By-Law offences (45),

Trespass to Property Act (50),

Controlled Drugs and Substances Act (5),

Compulsory Automobile Insurance Act (4).

Greeno said this is a "substantial increase from last year when we had 197 charges laid."

Criminal code charges included offences like: causing a disturbance, assault with a weapon, possession of a weapon for a dangerous purpose, carrying a concealed weapon and impaired driving.

"We had an incident where officers were responding to a disturbance call and…they located a male with a knife attempting to allegedly cause harm to other people in the area," said Greeno.

"So there was that and a bunch of assaults causing disturbances, a serious drug overdose and a lot of alcohol related things."

In the weeks leading up to St. Patrick's Day, police had plans to crack down on the street over crowding and liquor licence violations. WRPS also brought in officers from Peel Regional Police Service for extra security.

The 2017 Ezra street party cost police an estimated $120,000, and this year the costs were expected to rise.

Police have yet to release the cost of policing the party or the cost of any damage to the street or surrounding residences.

'Significant pressures on our resources'

Region of Waterloo Paramedic Services said they saw an increased demand throughout the day Saturday, continuing into Sunday morning.

Crews responded to a total of 70 calls between 10 a.m. Saturday to 3 a.m. Sunday, said deputy chief Kevin Petendra.

He said 40 of the patients were transported to local hospitals.

In an email to CBC News, Julie Kalbfleisch, a spokesperson for the region's paramedic services, said the large crowds on Ezra Avenue made finding and accessing patients difficult for paramedic crews.

She said there were 12 specifically trained paramedics responding to calls on foot in the Ezra Avenue area and four designated ambulances brought in to help manage the increased demands of the massive street party.

Kalbfleisch said although the number of patient transports mirror previous years, the concerned lies in the severity of the calls.

"12 patients transported were in critical or serious condition all related to alcohol and substance misuse," she said.

"These critical patients put significant pressures on our resources and the resources at our local hospitals."

52 total hospitalizations

On top of the 40 patients who were transported, 12 other patients — for a total of 52 hospitalizations — self-admitted themselves to Grand River Hospital (GRH).

"We did see 52 patients arrive from Saturday morning through to early hours of Sunday morning," said Jill Schitka, manager of the emergency department at GRH.

"52 different patients related to the St. Patrick's day Ezra street party and other parties that were probably off-shoots of that Ezra street party."

She said every patient was intoxicated from alcohol. Some patients had injuries related to overindulgence, she said, including falling down, getting a cut, hitting the head, falling from a tree or roof or injuries from assault or getting into a fight in the crowd.

'Treat the sicker first always'

She said having such a large number of people go to the emergency room in such a short period of time "definitely" strained resources, but GRH planned ahead and increased staffing.

Even so, there were longer than normal wait times for some patients — but Schitka said GRH will "treat the sicker first always."

"There were some longer waits probably for the less acute patients who were safe to wait due to the amount of people who came in a short period of time," she said in an interview with CBC News Monday.

"The people that were sicker, and maybe not a part of the St. Patrick's day festivities were seen in a timely manner.

10 to 15 of the patients from Ezra Avenue had serious injuries, and one patient was in life-threatening condition and remains in hospital in stable, but critical condition, said Schitka.

She would not elaborate on the cause of the patient's critical condition, but said it was alcohol-related and there was no fall or laceration.

Additionally, Waterloo Fire Rescue Services responded to 40 calls during the day, nine of which were for activated alarms and 24 for medical issues.