Complex sentence: The Works at Tynant had used up to 3.9 million litres per day (Ml/d) from Nant Myddlyn and a borehole and occasionally, water abstraction at the Works had caused Nant Myddlyn to dry up.
Split into simpler sentences: The Works at Tynant had used up to 3.9 million litres per day (Ml/d) from Nant Myddlyn and a borehole. Occasionally, water abstraction at the Works had caused Nant Myddlyn to dry up.