Evaluating or Testing Utility SCADA Security?

EncryptedBit writes: I am a local elected official involved in bringing new water and waste water treatment plants online in a small town. The new plants will incorporate SCADA, which can be used to change operational aspects at the plants, up to forcing a shutdown or changing operational parameters. Can any Slashdotters recommend ways to make sure it is secure? Any testing recommendations? The operational engineers are oblivious to security and SCADA is a new factor, so this concerns me. Thanks for any pointers!