There is a LOT of regulation on stocking carp, so that also means that public sources of breeding carp are hard to find and risky to use. Most wildlife operations for carp will get a permit and then buy and stock only sterile fish (triploid) which are very expensive.
If you determine you can ignore regulations, just catching some in local ponds can work -- the wildlife dept even conveniently tells you ponds with known invasive carp.
If you have trouble, I can let you know some side waters of the Columbia river where grass carp can be found.
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