Is it just me or is Face dancers' "Poison water" so much poorer an ability than "Foster unhappiness"? I take into account there is not really a surplus of happiness for most of the time, though extra health is still easy achievable (Deliverator pronounced it will be changed).
Let's take an example: city with Pop 8, all the producing fields are down, all the water (-16 or -20!), hammers, solaris... diminishing pop follows very quickly. With poison water (-15 MAX), it is only a good chance of loosing one citizen, with all face dancers' bonuses - maybe two, production unaffected. First effect lasts for 8 turns, the second - 5 turns (or more with bonuses?).
Now, with a, say, 16 pop city, unhappiness still halves the city production, and poison does what? with a water tank so full at this level, there is a thin chace of causing anything but a stagnancy of growth! Big deal, horrible Tleilaxu plagues! The price of both missions is just the same, so posioning is an option for hard-core role-players only?
I would suggest doubling the severity of all the posioning and still maybe it shouldn't wear off gradually? Increased cost may be necessary, though making "unhappiness" more expensive seems more like it.. Why to destroy production if you can just slow it so much for so many turns? (gov will preserve water as a priority).