first flush

noun3

1. •
   The first growth of buds, flowers, seeds, or whatever is harvested from a plant.

   • But, because the first flush of growth is from a preformed bud and subsequent flushes are from buds developed during the current growing season, chilling directly affects only the first flush. — 1979
2. •
   The beginning; the period of time when something is first starting.

   • And though his money was now gone again, all but a sovereign or two, yet that troubled him but little, in the first flush of being at sea. — 1849
3. •
   The flow of wastewater at the start of a storm or season, when runoff has the highest concentration of pollutants.

   • Several published data sets have been collected to evaluate the occurrence of a first flush of pollutants from urban watersheds. — 2005