dredging operations in the vicinity of the test 'boards. The san^jles 

 were collected at 6-hovir intervals throxighout a 2k-la.oxxr period. Each' 

 sample was taken at such time as to carrespond approximately with high- 

 tide and low-tide elevations, occurring from 1200 on June 2l»- to O8OO on 

 June 25, 19*+^. The results of these determinations indicate that the 

 5-day B.O.D. of the waters of Elliott Bay at the point of collection 

 varies from U to 6 and averages h.^^ ppm. A chemical analysis of these 

 san5)les indicates that the salinity of Elliott Bay water, "based on the 

 sulphate (SO^) content and chloride (Cl) content, is l6,055 ppm or 1,6 

 percent hy weight. 



A.36,03 Marine Borers * 



1. Teredinidae . Teredlnidae ( BanTria setacea ) were very active 

 at hoth locations throughout the period covered hy the tests. The attacks 

 were so destructive that panels were "becoming riddled in a few months. 

 The detailed figures coa the occurrence of Teredinidae at each of these 

 locations are summarized "below. 



a. XJSHS-1 (Pier No. 90 ). Teredinidae , ranging from minute 

 pits to minute specimens, occurred in 2k of the 55 control panels, the 

 "breeding season extending from the middle of March to the middle of 

 January. They occurred in all except one of the 55 test panels, "being 

 absent in the first of the It- panel series. The maximum length recorded 

 was 280 mm. (a"bout 11 inches) in a panel su'bmerged for 5 mjcmths.. Sixteen 

 of these panels were either filled or riddled, and they "became riddled in 

 the short period of 5 months. The attack at this location rated very 

 heavy each year, "beginning with 19kk. (See figure 10.) 



h, USHS-2 (Pier No. 91 ). Teredinidae , ranging from minute 

 pits to specimens up to it- mm in length, occurred in 22 of the 55 control 

 panels. At this location, the "breeding season clearly extended from the 

 middle of January to the middle of December. They occurred in all ex- 

 cept k of the k2 test panels, "being ahsent in i<- at the start of 5 differ- 

 ent series of panels. The maximum length recorded was 280 mm (about 11 

 Inches) in a panel su'bmerged for 5 months. Twenty-one of these panels 

 were either filled or riddled, and they "became riddldd in as short a 

 period as 5 months. The attack at this location rated very heavy in 

 19^5, 19^6, and 19^7. It dou"btleBS would have rated heavy also in lOkh 



had not the test "been interrupted "by loss of the "board. 



* 



2. Limnoria . Limnoria also were active each year at each loca- 

 tion, "but never occurred in particularly destructive numbers. Their 

 occu3:*rence, which was the same for each location, is summarized as 

 follows : 



a. USNS-l (Pier No. 90 ). Limnoria occurred irregularly on 

 20 of the 55 control panels, the maximum number of tunnels "being only 20 



159 



