An A320 Captain reported losing Green hydraulic system fluid in cruise flight. They ran the procedure; and after coordinating with Dispatch and Maintenance decided to declare an emergency. A normal landing was made although they encountered some wake turbulence on short final.

Narrative

During cruise; First Officer discovered the Green Hydraulic System quantity indication decreasing. It appeared to be a slow leak; but also thought it might be due to cold soaking. While monitoring the situation; I sent an ACARS message to Maintenance explaining the quantity indication was approaching the low level amber box; but no response. Sent another message asking if anyone was home and still no response. Contacted Dispatcher and he established a VHF conference call. All parties agreed we would be prepared in case the Green System failed. Instead of waiting for an ECAM to appear; we decided to be proactive and review the irregular procedure for Green Hydraulic Low Level; accomplish the performance computations and brief the Flight Attendants on the potential of a cabin advisory in advance. Upon initiating our descent received an ECAM for Green Hydraulic Low Level and accomplished the procedure. I then notified ATC of our issue and after a brief discussion with the First Officer; elected to declare an emergency as a precautionary measure. We then sent an ACARS to Dispatch and Maintenance confirming our mechanical problem and briefed the Flight Attendants on a cabin advisory; followed by a PA to the passengers informing them of situation and what they could expect. Fortunately; when we turned the Green Hydraulic Pump back on; per the ECAM; we regained enough hydraulic quantity to put the landing gear down; land without incident and taxi to the gate. CFR followed us to the gate and the flight was complete at this point. NOTE: I felt the entire crew; Dispatcher; ATC and CFR all performed extremely well; but with respect to Maintenance I have some concern. Throughout the majority of my career; Maintenance was considered to be a valuable resource and the technical experts we could rely on. I do not find this to be the case anymore; especially with the individual that was on duty during this event. Unfortunately; Maintenance Control has become extremely inconsistent; depending on which controller we draw for the day. This is a non-emotional comment and I strongly believe this issue needs to be addressed. Also prior to our landing; ATC departed a heavy aircraft; which left behind some wake turbulence we had to confront during flare. Had we been dealing with a controllability issue; this would not have been a good situation. I called the Tower from my hotel that evening and briefed them on what had transpired.