Per this site which goes back to 2001, the United States was sending $20-40 thousand for what I interpret as drug enforcement programs. From 2003 through 2014, the amount jumped to in excess of $20 million with almost all the increase getting spread out across most of the provinces for environmental programs such as wetland preservation. Why? What changed in 2003 to warrant the implementation of the program?
You point out that there was some aid to this border country for drug enforcement up until 2001. That date gives the clue that the aid from then on was focused on some new, more expensive threat…
Look, I know it’s GQ, but it’s Sunday, so don’t make me go prove it’s because of terrorism. But it’s because of terrorism. 
It looks like the majority of the money were grants under the North American Wetlands Conservation Act, which authorizes the Fish and Wildlife Service to give money to groups in the US, Canada, and Mexico to preserve and restore wetlands. The majority of the funds seem to have gone to Touchwood Hills, a marsh in Saskatchewan, Nicolet March in Quebec, the Nature Conservancy of Canada, and to Killarney Provincial Park in Ontario.
This is the 2016 Migratory Bird Conservation Commission report. Grants to Canadian sites are on page 42.
Whenever the USA is focused on something that includes cross-border planning and implementation involving Canada, the USA calls it foreign aid.
For example, when the USA is focused on terrorism, cross-border planning and implementation involving Canada is called foreign aid, and when the USA is focused on narcotics, cross-border planning and implementation involving Canada is called foreign aid.
Well, the same applies when the USA is focused on migratory birds, which have been having a hard go of it in the USA. To get migratory bird numbers back up, habitat must be increased. Canada is where a great many migratory birds hatch, so the greater the increase in habitat in Canada, the more birds will migrate through the USA. When Ducks Unlimited uses USA funds to coordinate projects in Canada for the benefit of hunters in the USA, its called foreign aid.
The big jump in 2001 in what the USA calls foreign aid to Canada was the implementation of theNORTH AMERICAN WETLANDS CONSERVATION ACT
[Public Law 101–233, Approved Dec. 13, 1989, 103 Stat. 1968]
[As Amended Through P.L. 111–149, Enacted March 25, 2010]
AN ACT To conserve North American wetland ecosystems and waterfowl and the
other migratory birds and fish and wildlife that depend upon such habitats.
In addition to what’s already been said, we do conduct significant drug enforcement operations with our neighbors to the North. There’s a considerable amount of regulated traffic crossing that border, and the RCMP has been tremendously helpful in many cases. I worked on a multi-drug case coming out of Europe that they were instrumental in facilitating, as well as at least one significant narcotics-related counter-terrorism case.
There’s a reason they’re one of our closest allies.
Also, money flows in both directions.
The USA has bribed a hell of a lot of countries to enforce it’s demented War on Drugs and to bind them into this holy war with covenants of steel ever since the first, when it convened the 1912 International Opium Convention.
Morality is all.
I agree that it is moral to invest a little money in the preservation of wilderness wetlands.