If State and Federal permit requirements are met, serious problems 

 are not foreseen with displacement of habitat by open-water 

 aquaculture operations. 



Changes in Water Use 



Aquaculture, particularly in more arid areas, may compete with 

 other uses for groundwater and surface water. Except for closed 

 systems, aquaculture uses large quantities of water. A dramatic 

 increase in inland aquaculture facilities in concentrated areas 

 could reduce the initial availability of groundwater for various 

 other uses. However, in many regions of the country, water 

 captured in ponds provides opportunities to conserve water and 

 extend the availability of water for other purposes. 



Effluent Discharge 



Generally, effluent from aquaculture facilities poses only a 

 limited threat to the aquatic environment. Potential impacts ' 

 include high biological oxygen demands and eutrophication resulting 

 from the discharge of organic materials, algae or other secondary 

 growths, and nutrients such as nitrogen or phosphorus. 



In most instances, the use of available treatment techniques and 

 subsequent dilution in the receiving waters render's hatchery and 

 grow out facility discharges harmless. However, in the absence of 

 good management practices, an aquaculture facility could overload a 

 small stream, lake, or lagoon. 



Although concerns have been expressed about raceway facilities, 

 because of the large volume of water utilized, the effluent Is 

 actually very dilute when compared with municipal effluent. Fish 

 hatcheries have been responsible for water quality degradation in 

 some instances, but the overall impact created by these discharges 

 has generally been limited. In several studies it was demonstrated 

 that hatchery effluent treatment, beyond simple settling of solids 

 resulting from cleaning operations, should not be required. In 

 closed systems concerns over discharges are practically eliminated, 

 as these facilities discharge little or no effluent. 



Physical and Biological Barriers 



Certain types of aquaculture facilities situated in coastal waters 

 may form barriers which hamper the migration of aquatic organisms, 

 such as fish or shellfish, retard the movement of water (currents 

 and tides) , or hinder navigation. Nets or other structures placed 

 across water courses may block or alter the movements of animals or 

 people. Careful siting and attention to Federal, State, and local 

 permit requirements should prevent significant problems. 



63 



