Natural History Timeline

Natural History Timeline of the Boulder Valley


13000 BC
9500 BC to 1850AD
500 BC
  • World population: 100 million
1492
1539
1600s
1650
  • World population: half a billion.
1620
1680

1700s
  • Invasive weed teasel introduced to North America.
1776
1793
  • First reports of cheat grass in U.S. Cheat grass was probably introduced to both East and West Coasts directly from Europe.
1804
  • World population: one billion
1820s
  • Otter and beaver trapping begins on the streams of the Rockies, ending beaver impoundments in riparian areas for decades.
  • Bison are extinct east of the Mississippi.
1823
1830
1859
1860
1862
1863
  • Boulder’s first reservoir, Pancost Lake, is constructed at the site of what is now Leggett-Owens reservoir.
1864
1869
  • Bounty on wolves enacted in Colorado.
1872
1873
1874
1875
1870s
  • Boulder flour mills, powered by ditches, grind wheat for locals and the East.
1884
  • 1091 bison remain in North America.
1885
  • First Arbor Day celebrated in Colorado. CU students and faculty transplant cottonwoods from Boulder Creek to around Old Main.
1887
  • Boulder’s last irrigation ditch begins construction.
  • Ditches over-appropriate Boulder and South Boulder creeks.
  • Boulder's reservoir building era begins.  
  • Reservoirs capture spring peak flows.  Return flows to the Platte allow ditches to be developed farther east on the South Platte. 
  • Greenback trout become rare, due to sediment, toxic mine tailings, over-harvesting, agricultural diversions and interbreeding with non-native trout.  
  • Long-billed curlew populations begin sustained decline.
1890
1893
  • Bounty enacted in Colorado ($1 for coyotes, $10 for cougars and bears).  
  • Last river otters reported of on South Platte.
18941897
1898
1900's
  • North American bullfrog introduced to Colorado, perhaps through fish stocking programs.  
  • Fox squirrel introduced to Colorado.  Fox squirrels expand their range by following riparian corridors, invading urbanized areas, and inhabiting areas newly cultivated with deciduous trees.
  • Tamarisk planted for erosion control on the Colorado and Rio Grande rivers. 
  • Bubonic plague enters the Western ecosystem from an outbreak in San Francisco.
  • Last mink reported in Boulder Creek. 
1906
1908
1910
  • Nationally, 5 million acres of forest burn and 78 people are killed in forest fires.  Active suppression by U.S. Forest Service of all forest fires begins.
1919
1920s
  • Cheat grass infests entire West and considered the worst noxious weed. 
  • Goose populations plummet nation wide from habitat loss and over-hunting.
1924
1927
  • World population: 2 billion.
1929
1933
1937
1938
1939
1943
  • Last wolf in Colorado is killed. 
  • Plague reaches the Front Range of Colorado.  
  • Russian olive is distributed widely for wind breaks in the West.
1945
1954
1955
1957
  • A remnant group of greenback trout is discovered in upper Boulder Creek watershed.
1958
1959
  • PLAN-Boulder is organized.   
  • Less than 450 nesting pairs of bald eagles remain in the Continental U.S.
  • 40 captured Canada geese are released in a Fort Collins lake and supplied with nesting boxes. These "live decoy" geese lure in migrating geese to Front Range lakes.
1960's
1962
1965
1967
1970
1972
1973
1975
  • World population:  4 billion. 
  • 39 breeding pairs of peregrine falcons remain in U.S.
1976
1977
1978
1979
1980s
1986
1987
  • World population:  five billion.
1990
  • City of Boulder dedicates a portion of its senior ditch rights to in-stream flows in Boulder Creek through town.
1992
1993
1994
1995
1996
1998
1999
  • World population:  six billion. 
  • West Nile virus enters U.S. near New York City.
2001
2002
  • West Nile virus reaches Boulder and decimates corvid (crows, magpies, ravens etc.) and other bird populations. 
  • Bald eagles begin nesting along Boulder and St. Vrain creeks.  
  • About 380,000 bison live in North America.
2003
2004
2005
20062008
2009
2011
  • World population: 7 billion
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