Lack of Licensing: Over three million dollars not realized
Multnomah County estimates that there are 223,000 in the county with 178,400 dogs in Portland. Given that there are 60,000 licensed dogs, this means 70% are unlicensed. This works out to $3,552,000 of unrealized revenue. That's a lot of money for a county and city whose coffers are empty. 

Dogs off leash a mere 10 feet from the sign that notes dogs should be leashed at beach school in North Portland. Note the presence of children on the playground. Two weeks prior to this photo being taken. a parent was bit by an off-leash dog while picking up his child from school.

MULTNOMAH COUNTY AND CITY OF PORTLAND DOG LAWS

Parks & Recreation Recreation Dogs & Off-leash Areas Laws & Rules
https://www.portlandonline.com/parks/index.cfm?a=91711&c=39524

Licensing Information
http://www.multcopets.org/licensing-information
Multnomah County | CHAPTER 13: ANIMAL SERVICES
http://web.multco.us/sites/default/files/county-attorney/documents/ch13.pdf

ANIMAL CONTROL, RELATING TO TETHERING
http://web.multco.us/board/documents/amending-mcc-chapter-13-animal-control-relating-tethering

Pets Trespassing & At Large
http://www.multcopets.org/animal-nuisances/pets-trespassing-large