I went to my Credit Union yesterday and I asked them if they offer a checking and/or saving account in Canadian Dollars. Unfortunately, they don't offer such account.
Where can I open one? Is it possible?
I'd look into HSBC. They operate in Washington as well as across the border in BC. If you can't open a CAD account locally, they can help you open and manage one in Canada from the US. It may or may not require having a small business account instead of a personal account.
If you can make the trip to BC yourself, I'd recommend opening an account with TD. They are apparently the only Canadian bank that will allow non-residents/citizens to open an account. The customer service is great and they have a good online banking site that should allow you to manage it from the US.
Royal Bank in Canada can open an account for you in the US through RBC (the US affiliate to Royal Bank of Canada) I think it's called RBC Access USA.