16 Artificial Aquatic Habitats 



Aquatic animals and plants might be arranged in a scale of decreasing 

 ability to traverse the gap between one body of water and another, with 

 some moving in almost as soon as a new lake has been created but with 

 others arriving less rapidly. In fact, opportunities for the movement of 

 some aquatic organisms may be so infrequent as to require many years 

 for their arrival, and others, lacking their usual mode of transportation, 

 may never breach the gap. Certain organisms may gain entry as a result 

 of accident or stocking by man. Because of these variations in migration 

 time and the relatively short existence of artificial lakes, populations of 

 their organisms are usually simpler than those of natural ones. 



Motivation for the construction of artificial lakes varies with our need 

 for water. Today in the U.S. we inhabit all of our arable lands, and must 

 devise ways to supply water for diverse uses. Although sometimes water 

 problems are related to too much water, usually the amount is inadequate 

 or availability is not synchronized with need. 



At the turn of the century, engineers envisioned multiple uses for 

 impoundments. Reservoirs were built on community, state, and federal 

 levels to supply water for cities and industries, to irrigate dry lands, and 

 to generate power. More recently, impoundments have been constructed 

 to supply water for navigation during dry seasons and to control floods 

 during abnormally wet ones. However, it was not until the 1930's that 

 many reservoirs were built for recreational purposes, because aquatic 

 recreation had little or no recognized monetary value prior to this time. 



After the drought and depression years of the 1930's, considerable in- 

 terest centered on farm ponds, largely as a result of the activities of the 

 U.S. Soil Conservation Service which began during that period. Not only 

 were ponds promoted as sources of water for stock but also for their use- 

 fulness as a general farm-water supply for orchard spraying, fire protec- 

 tion, limited irrigation in dry years, and for recreation in the form of fishing, 

 swimming and boating. Furthermore, the damming of eroded gullies 

 stopped the movement of soil down hill so that impoundments created by 

 these dams could be combined with contour plowing and strip cropping 

 as an integral part of the soil and water conservation plan. 



Other types of artificial water resulted from man's activities in digging 

 at the earth's surface for sand and gravel, limestone and other rocks, coal 

 and other minerals. The empty holes became filled with water and formed 

 ponds and lakes. 



These, then, are the artificial waters available for fish management. 

 They are often more manageable than natural lakes because they are 

 man-created and are so engineered that they can be better manipulated: 

 In some, construction was originally planned to give maximum recrea- 

 tional values; in others, recreational uses were planned to follow an 

 original but transitory value (such as the removal of gravel). 



