K1 long term capital gain taxable in Washington State?

[x_m_z]

I am a resident of Washington State and recently received a K-1 form from a private investor partnership located in California. Box 9a, "Net long-term capital gain" shows more than $250,000 (the partnership sold a California business shares they invested in several years ago). Does this amount qualify as taxable "long-term capital gains" in Washington state?

Thank you for your help.