paying taxes in real estate capital gains in another state

[Richard Tyler]

Hi everyone.  I live in California.  I just sold a vacant lot in Oregon that I had owned for 2 years.  I made about $20k in profit in long term capital gains.  On my 1040 form, I have about $30k to write off for my long term capital loss.  My tax person told me that I don't have to pay any federal taxes because I have that write-off.  However, I was told that I need to pay about 8% tax to the State of Oregon for that $20k profit.  

I don't understand why I need to pay taxes to the State of Oregon for that capital gains since I have a long term capital loss on the federal level.  Has anyone here gone through something similar?  Thanks.