The Lake Mother was an elderly person full of white hair and wrinkles, but her energy signature was a totally different thing. Not only she was strong, but there was an endless supply of energy connected to her by a formation. That formation served as a protective measure too, helping to maintain everything at place and working.
Seth was able to feel that if not because of that strong formation supplying her energy, together with her own powerful cultivation, she wouldn't have been able to handle the situation she was in until now.
The Lake Mother had her eyes shut, but she was not unconscious at that moment. It's just that she was concentrating on controlling the poisonous aura inside her energy veins. Seth noticed that her life signals were weaker than normal, but that was something to be expected, since she was not only old, but was stranded day and night in a constant fight against a wicked poison.
