
                                  MEMORANDUM


Tetra Tech, Inc.
10306 Eaton Place, Suite 340
Fairfax, VA 22030
phone	703-385-6000
fax	703-385-6007


TO:			Record
FROM:		Kelly Meadows
DATE: 		February 24, 2011

SUBJECT:	Spawning seasons

The attached documents present information on the spawning seasons of various aquatic species.

Attachment A	(Spawning Season for Selected Fishes) illustrates the spawning period for a number of common fish species found in each waterbody type.  As shown by the graphic, spawning occurs at all times of the year (i.e., "entrainable" organisms are likely to be present at any time of the year, depending on the waterbody).
	
Attachments B through F were developed using site-specific data at individual facilities in New England and serve as illustrative examples.  These plots show that, for some locations, the spawning seasons for organisms present in the source water may span most or all of the year; in some cases, flow reduction throughout the year (e.g., converting to closed-cycle cooling) may be the most appropriate technology option.  However, the peaks of these spawning periods would be when the highest concentration of entrainable organisms would be present; as a result, there may be opportunities for seasonal intake flow reductions that would achieve significant reductions in impingement and entrainment.  Another factor to consider is what species are considered important; these graphics illustrate most of the species present at these sites, but resource managers may choose to focus on selected species of concern, which may narrow the scope of peak spawning periods, providing additional opportunities for flow reduction to be utilized.
