Force of Nature - A New Lake Created

I visited the old sand quarry, which is deserted and much of it has been regenerated to become an unofficial nature reserve. Following heavy falls of rain, a small lake usually appears at one end of the quarry. This is what I anticipated to find, however, what met my eyes was something totally unexpected.
Instead of a lake stretching just twenty metres across, the whole of the quarry was full. In extent, it probably stretches to four hundred square meters, though this is very difficult to estimate as it does not comprise of a single area, the quarry being almost 'U' shaped. This new lake is at least three meters deep in places and is far beyond what might be expected even given the flooding that has followed the recent rains. I was quite perplexed by this sight.
Taking a detour from the walk I had planned, I eventually emerged on the footpath at the other side of the quarry. This path follows the route of a small stream. At one point it became apparent that my path was blocked by a fallen tree; not an unlikely event in the present climatic circumstances. Upon closer inspection I could see that there had been a substantial landslip. Several trees were now rooted some two meters below the level where they had previously been. The stream bed was also well above the level of the land. At the further end, a waterfall revealed the upstream flow. The water could not continue on its usual course and so was flowing into the quarry.
The result of this could be the creation of a permanent lake presenting new environmental opportunities. But, I am wondering what will happen once the level of the lake reaches that of the inflowing stream. If the water backs up from there, it could cause all manner of other problems and presumably, the authorities will have to take action to avert this. It will be fascinating to await the outcome.