Fig. 3: Global patterns of the required reduction in watershed net anthropogenic N input (NANI) to achieve the lake water quality goal (≤1 mg N L–1) within 10, 20, 30, and 40 years.
From: Coupling nitrogen removal and watershed management to improve global lake water quality
a–d Blue polygons represent lakes with ≤1 mg N L–1, and for those lakes there is no need to reduce NANI. The deepest yellow polygons represent lakes that could not achieve the water quality goal within the target timeframe, even if the NANI in those watersheds is reduced to zero. Data are shown at the HydroSHEDS level-5 watershed scale. Gray areas indicate areas with no data available. e Number of regional lakes that require no reduction in NANI to achieve the water quality goal. f Regional NANI reduction required to achieve the water quality goal. g Number of regional lakes that cannot achieve the water quality goal within the target years regardless of watershed management practices.
