The previous builder had run the pipe over the liner, creating this muddy leaker.
Excessive water on the outside of this liner indicates a leak nearby. Failure of the seal between the skimmer weir and the liner is the most likely culprit.
An ugly, leaky waterfall transforms, before.
After the repair, a peaceful-looking, better-sounding water feature.
Roots from nearby plants can grow over the liner edge in search of water. They often develop a "witch's broom"
appearance as they grow and expand to absorb lots of that good old pond water.
Water is only meant to be on one side of this liner, so puddles on both sides indicate trouble.