﻿452 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  and 
  on 
  May 
  20th 
  the 
  mean 
  discharge 
  at 
  Rochester 
  was 
  12,900 
  

   cubic 
  feet 
  per 
  second. 
  Flood 
  discharges 
  of 
  these 
  amounts 
  are 
  

   sufficient 
  to 
  render 
  farming 
  operations 
  impossible 
  on 
  'a 
  consider- 
  

   able 
  portion 
  of 
  the 
  flat 
  area. 
  On 
  June 
  2, 
  1889, 
  the 
  discharge 
  at 
  

   Rochester 
  was 
  about 
  20,000 
  cubic 
  feet 
  per 
  second, 
  and 
  from 
  per- 
  

   sonal 
  observations 
  on 
  that 
  day 
  it 
  is 
  known 
  that 
  nearly 
  the 
  whole 
  

   flat 
  area 
  of 
  the 
  valley 
  was 
  flooded. 
  The 
  answer 
  to 
  the 
  question 
  as 
  

   to 
  the 
  value 
  of 
  the 
  annual 
  overflow 
  is, 
  therefore, 
  that 
  in 
  the 
  case 
  

   of 
  the 
  Genesee 
  valley, 
  the 
  May 
  overflow 
  comes 
  at 
  such 
  a 
  time 
  as 
  to 
  

   do 
  only 
  injury, 
  without 
  any 
  opportunity 
  to 
  realize 
  what 
  would 
  be, 
  

   if 
  the 
  inundation 
  came 
  only 
  in 
  March 
  or 
  April, 
  a 
  great 
  benefit. 
  

  

  The 
  cash 
  value 
  then 
  of 
  so 
  regulating 
  the 
  flow 
  of 
  the 
  river 
  as 
  to 
  

   do 
  away 
  with 
  the 
  May 
  overflow 
  can 
  be 
  estimated 
  as 
  an 
  average 
  of 
  

   80 
  square 
  miles, 
  at 
  say 
  f 
  40 
  per 
  acre, 
  or 
  the 
  increased 
  valuation 
  of 
  

   the 
  whole 
  area 
  would 
  be 
  about 
  $2,050,000. 
  

  

  Moreover, 
  the 
  flats 
  above 
  Rochester 
  are 
  a 
  further 
  benefit 
  to 
  the 
  

   lower 
  river 
  by 
  reason 
  of 
  an 
  immense 
  storage 
  of 
  ground 
  water 
  

   therein, 
  which, 
  as 
  the 
  flood 
  level 
  subsides, 
  gradually 
  runs 
  out 
  with 
  

   the 
  result 
  of 
  greatly 
  decreasing 
  the 
  period 
  of 
  extreme 
  low 
  water. 
  

  

  Again, 
  in 
  case 
  of 
  excessively 
  heavy 
  rains, 
  in 
  the 
  middle 
  of 
  the 
  

   summer, 
  from 
  the 
  effect 
  of 
  which 
  the 
  river 
  channel 
  is 
  temporarily, 
  

   partially 
  or 
  wholly 
  filled, 
  such 
  an 
  amount 
  of 
  water 
  is 
  stored 
  in 
  

   these 
  flats 
  as 
  to 
  keep 
  the 
  river 
  comparatively 
  well 
  up 
  during 
  the 
  

   fall. 
  

  

  This 
  actually 
  happened 
  in 
  the 
  season 
  of 
  1893, 
  when 
  on 
  August 
  

   29, 
  1893, 
  there 
  occurred 
  a 
  rainfall 
  of 
  nearly 
  three 
  inches 
  over 
  the 
  

   whole 
  catchment 
  area 
  in 
  a 
  period 
  of 
  about 
  12 
  hours, 
  which 
  pro- 
  

   duced 
  a 
  flood-flow 
  of 
  5800 
  cubic 
  feet 
  per 
  second 
  at 
  Mount 
  Morris 
  

   and 
  3800 
  cubic 
  feet 
  at 
  Rochester, 
  an 
  amount 
  of 
  water 
  sufficient 
  

   to 
  partly 
  fill 
  the 
  channel 
  between 
  these 
  two 
  places, 
  but 
  without 
  

   any 
  overflow 
  of 
  the 
  adjoining 
  flats. 
  Previous 
  to 
  this 
  heavy 
  rain- 
  

   fall 
  the 
  mean 
  flow 
  at 
  Rochester 
  had 
  been 
  for 
  a 
  month 
  about 
  300 
  

   cubic 
  feet 
  per 
  second. 
  At 
  Mount 
  Morris 
  it 
  had 
  not 
  averaged, 
  for 
  

   the 
  same 
  period, 
  more 
  than 
  125 
  cubic 
  feet 
  per 
  second. 
  The 
  effect 
  

   of 
  this 
  rain 
  on 
  the 
  ground 
  water 
  of 
  the 
  flats 
  is 
  strikingly 
  shown 
  by 
  

   comparing 
  the 
  flows 
  at 
  Mount 
  Morris 
  and 
  Rochester, 
  when 
  it 
  will 
  

   be 
  found 
  that 
  on 
  September 
  3 
  the 
  flow 
  at 
  Mount 
  Morris 
  was 
  again 
  

   down 
  to 
  200 
  cubic 
  feet 
  per 
  second, 
  and 
  remained 
  below 
  that 
  figure, 
  

  

  