what to do with tadpoles..?!

[Hubble]

Can anyone help!? I am a newbie.
My mother in law gave us a load of tadpoles for our toddler to watch grow. We started with about 30 but had a disaster and lost all but 6 of them. The 6 survivors now have 4 legs and a couple have lost their tales. I've put some ledges in their tub and have been feeding them powder food and mushy lettuce.... my problem is what on earth to do with them now. we don't have a pond. Are there rules / guidelines about where / when is safe to release them? My husband suggested the local reservoir..... is that allowed?!?! I don't know anyone with a pond and I don't think the woman who gave them to my mother in law wants them back (or perhaps she's expecting 40 odd back! - eek!)
I would be grateful for some ideas!

[Mark_b]

Really they should be returned to the place the spawn was taken from for numerous reasons (including stopping the spread of disease). If this isn't possible then try and find another pond really close to the original one and place them in some vegetation cover next to the water body