3. Remove salt crusts periodically. 



4. Prevent the complete drying out of evaporation ponds or pond cells. As there is 

 some uncertainty as to whether the periodic drying out of ponds reduces biota 

 and hazards to wildlife, further research needs to be carried out. Until these 

 uncertainties are addressed, evaporation ponds should not be dried out (Depart- 

 ment of Water Resources, 1988). Also, during the drying phase, more wildlife 

 may have access to contaminated water. 



5. Use blue-green algae to seal the pond bottoms instead of interceptor drains to 

 minimize seepage. It has been reported that 3-12 months after applying blue- 

 green algae, complete sealing occurs in salt- producing ponds. Although the cost 

 of algae treatment is less than interceptor drains, the effectiveness is still 

 undetermined (Department of Water Resources, 1988). 



6. Consider ORMAT, an evaporation enhancement system. ORMAT is designed to 

 increase the evaporation rate of water by reducing the water to fine droplets. The 

 total surface area of droplets is greater than a surface water body of the same 

 volume of water. This, in turn, leads to an increase in the rate of evaporation. 

 Since a higher rate of evaporation is achieved, smaller ponds would be required. 

 ORMAT is commercially used in Israel and has been utilized in the U. S. 

 (Bradford et al., 1989b). Since performance information concerning ORMAT is 

 limited, the efficiency in increasing evaporation ratesof water is not known. In 

 addition, a high cost of set-up and operation could hinder widespread applica- 

 tion. 



7. Use Iron Sulfide (FeS^) Sealing. Paul and Clark (1989) stated that Soviet 

 workers found that a buried layer of straw approximately 15 cm thick covered 

 with another 15 cm of soil results in the sealing of soils under ponds by means 

 of a gleying reaction (decay of organic matter resulting in the reduction of Fe** 

 to Fe^* and SO^' to S^ . As a result of that reaction, FeS^ is precipitated and soil 

 colloids peptize. This procedure is inexpensive, and might be used in reducing 

 or preventing seepage leading to contamination of groundwater. 



Constraints 



The above best management options and design features may be overridden by consid- 

 erations to make evaporation ponds least attractive to wildlife and reduce potential contaminant 

 hazards to wildlife. 



page 9.5 



