EMB-145 Captain reported receiving a HYD LO QTY EICAS Advisory in cruise. The #1 system continued to degrade; so the flight crew ran the QRH; which led to review the Hydraulic System 1 Failure QRH. Flight crew elected to perform an air turn back to the departure airport.

Narrative

The flight began normally with a takeoff from XXL to climb via the ZZZZZ.1 RNAV SID. We leveled off at FL320 and completed the cruise check. Shortly after passing ZZZZZ intersection we received a HYD LO QTY EICAS Advisory. We immediately checked the Multi-function Flight Display (MFD) HYD page and realized the Hydraulic Fluid Quantity on System 1 was at the top of the Amber Band. As I was pilot flying; I transferred flight controls and radios to my First Officer (FO) and ran the Hydraulic System Low Quantity QRH. The QRH led us to review the Hydraulic System 1 Failure QRH on another page. As we preemptively reviewed the System Fail QRH we discussed the potential system losses and options available to us. During this time we monitored the Fluid Quantity and noticed that the Quantity continued to fall rapidly. After approximately 5 minutes; the Quantity was in the middle of the amber band and I determined failure was inevitable. We both agreed to return to ZZZ. I called ATC; [requested priority handling]; and asked to return to field. Additionally; in anticipation of Hydraulic System Loss I commanded my FO to fly at 240 Kts. to avoid structural damage to the landing gear doors if and when they failed to the open position. ATC was advised of this speed restriction and gave us direct ZZZZZ1 for the ZZZZZ2 3. I called the Flight Attendant (FA) and gave her a briefing; indicating an arrival in 30 minutes and anticipation of a normal landing. At this point I received a ACARS from Dispatch inquiring why we were turning around. I advised we were returning for a potential HYD 1 Leak. ATC asked if we would need special preparations on the ground and I advised we may need a tug off the runway as we may not have steering capability. At this point we received a HYD SYS1 FAIL EICAS Caution and ran the applicable QRH. This was accompanied by AIL SYS1 INOP. Dispatch responded saying that Maintenance was wondering where we were indicating the HYD leak. I responded to Dispatch that we had HYD SYS1 FAIL and were a [priority handling] aircraft. I then briefed the STAR and approach to my FO and we discussed potential adverse outcomes and solutions associated with the system failures. At this point I took back flight controls and flew the STAR to an uneventful flaps 45 landing after manual gear deployment. After landing we must have regained some hydraulic fluid from the accumulators as I regained some system functionality; including steering. I slowed to approximately 10 Kts. or less and exited the runway at a high speed exit where I came to a stop after crossing the threshold. Tower gave us a frequency to communicate with Operations and Airport Rescue and Firefighting (ARFF) in order to confirm that the aircraft was safe. Additionally; Maintenance drove up the aircraft and inspected our Hydraulic System before we were given the OK to tug back to gate with passengers on board. I made an announcement after clearing the runway explaining the situation to the Passengers and ensuring them of their safety. The Passengers disembarked the aircraft normally at gate XXX and we were given a new aircraft at XXY to ultimately complete the flight to ZZZ1.Person A and Person B both acted with a high level of professionalism and played a critical role in the safe return of our priority handling aircraft.