That is exactly the same leak i had. The water outlet is failing, i would replace it asap. This is what mine looked like when i replaced it, see attached pic. Note, because of the hose i could not see the condition of the outlet till after i removed it.
If your still under warrenty it should be covered by chevy dealer. Id show them that pic and you could also show them the pic i uploaded after replacing.
Or
If your doing it your self;
* socket is a E10 star socket torq spec 71 inch/lbs.
* Get a new hose line from the radiator to the water outlet that is leaking and possibly new from reservoir tank to water outlet.
* Water outlet
https://www.amazon.com/gp/product/B014RF7SW6/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1
* coolant, dexos 50/50
* need to diconnect the wire harnesses to the coilpack, throttle body and throttle body charge hose, o2 sensor wire that is on the water outlet.
* options, you can drainthe system to the lowest point of the water outlet or flush the whole system and replace with new.
* disconnect hoses and remove old part, clean off the block, install new part and torq to spec and connect hoses, fill. Connect all the wires and tb chsrge hose and burp system.
If you need any more info, let me know. GL hope all goes well.