﻿472 
  NEW 
  YORK 
  STATE 
  MUSEUM 
  

  

  of 
  water 
  stored. 
  Probably 
  at 
  the 
  present 
  time 
  they 
  will 
  cost 
  some- 
  

   what 
  more, 
  but 
  for 
  water 
  storage 
  merely 
  they 
  will 
  not 
  exceed 
  $75 
  

   or 
  $80 
  per 
  million 
  cubic 
  feet. 
  On 
  the 
  Mohawk 
  and 
  its 
  tributaries 
  

   conditions 
  are 
  much 
  less 
  favorable. 
  Reservoirs 
  there 
  are 
  likely 
  

   to 
  cost 
  from 
  $200 
  to 
  $300 
  per 
  million 
  cubic 
  feet. 
  Hence, 
  as 
  a 
  

   financial 
  proposition, 
  the 
  Hudson 
  river 
  above 
  Mechanicville 
  is 
  

   likely 
  to 
  be 
  more 
  thoroughly 
  regulated 
  than 
  the 
  Mohawk 
  river 
  and 
  

   its 
  tributaries, 
  the 
  more 
  specially 
  since 
  water 
  storage 
  has 
  not 
  

   only 
  value 
  here 
  for 
  preventing 
  floods, 
  but 
  is 
  also 
  of 
  considerable 
  

   value 
  for 
  water 
  power. 
  The 
  same 
  is 
  true 
  on 
  the 
  Mohawk 
  river, 
  

   but 
  the 
  limit 
  of 
  cost 
  of 
  water 
  power 
  in 
  comparison 
  with 
  steam 
  

   power 
  will 
  be 
  much 
  sooner 
  reached 
  on 
  this 
  stream 
  than 
  on 
  the 
  

   upper 
  Hudson. 
  Since 
  this 
  phase 
  of 
  the 
  subject 
  is 
  extensively 
  dis- 
  

   cussed 
  in 
  the 
  first 
  report 
  on 
  the 
  upper 
  Hudson 
  storage, 
  it 
  is 
  merely 
  

   referred 
  to 
  here. 
  

  

  Floods 
  in 
  Croton 
  river. 
  The 
  catchment 
  of 
  the 
  Croton 
  river 
  consists 
  

   of 
  a 
  broken, 
  hilly 
  country 
  with 
  its 
  surface 
  soil 
  composed 
  princi- 
  

   pally 
  of 
  sand 
  and 
  gravel. 
  Clay, 
  hardpan 
  and 
  peat, 
  while 
  found 
  

   in 
  a 
  few 
  localities, 
  are 
  for 
  the 
  whole 
  area 
  only 
  present 
  to 
  a 
  limited 
  

   extent. 
  The 
  rock 
  formation 
  consists 
  generally 
  of 
  gneiss, 
  although 
  

   strata 
  of 
  limestone, 
  some 
  micaceous 
  and 
  talcose 
  slates, 
  with 
  veins 
  

   of 
  granite, 
  serpentine 
  and 
  iron 
  ore, 
  occur 
  in 
  a 
  few 
  places. 
  The 
  

   catchment 
  area 
  is 
  about 
  339 
  square 
  miles, 
  above 
  the 
  old 
  Croton 
  

   dam, 
  at 
  which 
  point 
  daily 
  gagings 
  of 
  the 
  stream 
  have 
  been 
  taken 
  

   since 
  1867. 
  According 
  to 
  J. 
  J. 
  R. 
  Croes 
  there 
  is 
  a 
  well-attested 
  

   case 
  of 
  a 
  maximum 
  flood 
  of 
  25,376 
  cubic 
  feet 
  per 
  second, 
  or 
  74.9 
  

   cubic 
  feer 
  per 
  second 
  per 
  square 
  mile. 
  In 
  reference 
  to 
  these 
  figures 
  

   it 
  may 
  be 
  remarked 
  that 
  probably 
  they 
  have 
  been 
  obtained 
  by 
  

   the 
  use 
  of 
  Francis's 
  formula. 
  The 
  profile 
  of 
  the 
  old 
  Croton 
  dam, 
  

   however, 
  shows 
  a 
  rounded 
  crest 
  which, 
  according 
  to 
  Bazin's 
  co- 
  

   efficient, 
  series 
  No. 
  193, 
  would 
  give, 
  with 
  about 
  5 
  feet 
  depth 
  on 
  the 
  

   crest, 
  a 
  discharge 
  from 
  37 
  to 
  38 
  per 
  cent 
  higher 
  than 
  Francis's 
  

   formula. 
  The 
  maximum 
  flood 
  of 
  the 
  Croton 
  may, 
  therefore, 
  be 
  

   from 
  30,000 
  to 
  35,000 
  cubic 
  feet 
  per 
  second, 
  or 
  possibly 
  as 
  high 
  as 
  

   103 
  cubic 
  feet 
  per 
  second 
  per 
  square 
  mile. 
  

  

  January 
  7-8, 
  1841, 
  a 
  severe 
  flood 
  occurred 
  which 
  washed 
  away 
  

   the 
  earthen 
  bank 
  of 
  Croton 
  dam. 
  At 
  that 
  time 
  the 
  ground 
  was 
  

   covered 
  with 
  eighteen 
  inches 
  of 
  snow, 
  and 
  rain 
  falling 
  continu- 
  

   ously 
  for 
  forty-eight 
  hours, 
  with 
  high 
  temperature, 
  produced 
  a 
  

   serious 
  flood. 
  The 
  overflow 
  weir 
  w 
  T 
  as 
  insufficient 
  to 
  discharge 
  the 
  

  

  