Jules,
PLEASE know that I am not picking on you and don't take this personal.. you may not know better but koi should NOT be in a pond as small as your pond, especially 30 Koi Plus Who knows how many goldies! :'(
Even this being a temporary situation, you are Way overstocked and this can result to fish disease, death, etc.
Koi are not colored goldfish, their requirements are much different than goldies and will grow big.
If you have to drain the pond to remove your koi, that will be less stress for them in the long run vs. keeping them in your small pond.
Do you have any family members or friends that can help you catch them?
Good luck,
Bonnie