Apparently, according to various sites, brewers in Newport, OR (Rogue) and Victoria B.C. pioneered the CDA style. I've found these style guidelines as well:
Cascadian Dark Ale
Aroma: prominent NW hop aromas: citrus, pine, resinous, sweet malt,
hints of roast, toast, chocolate malt, and/or Carafa
Flavor: A balance between NW hop flavor, bitterness, sweet malt,
subtle toast and roast, chocolate, Carafa. Black Patent is acceptable
at low levels, but should not be astringent. Some brewers prefer to
cold steep the dark grains to achieve a very dark beer without the
tannin contribution of adding the grains to the mash.
History: A style which emerged on the Northwest Coast of North America
in the early 21st Century. Northwest hops are prominent, balanced with
malt, dark malts give color and flavor, but body should be reminiscent
of an IPA, not heavy like a porter or stout. The style is not only
gaining traction with brewers in the Pacific Northwest, but is
starting to spread to other regions.
Classic Examples: Rogue Brewer, Phllips Black Toque, Barley Brown's
Turmoil, Walking Man Big Black Homo, Rogue Black Brutal, Pelican Bad
Santa, New Holland Black Hatter, Laughing Dog Dogzilla
IBUs 45-90
Abv 6-8.5%
