i co tl> hee of the pover dams -- they don't need to make so much clectricity, so we have a fluctuation in the gone wWaich is not too good Lar the attached algae, We have a mat of algae on the bottom which bocemes erudded uo with all kinds of material floating down the river and what wo aro msasuving thoro in torms os aigae -- it is Qiffieult to separate what is activity in the algae and the other organic waterials which have gott2n into the Iilm, so we find in similar Plankton, the alsae, and we have dono this tor noapy years, but we chanzs syecics vory rapicly in the river and tho ameunt of debris which is collected there is a function of % what hapyvened to the river the woeok betore, so, in terms of consistent types of information, the algae in the bottom is about the Worst sort of thing we can neasure. . FROI] Ti FLOOR: Is it the adseorptien phenomenon or what? | DR, FOSTER: This is ono waich wo think will probably -~ Straight adsorption in Plankton may act for a vory high percentage of tho total amount that is there. FROM THO FLOOR: with cat-tails. We did some of that, and we did it We got sems cat-tails and a good bit of it was absorption and a good deal of it was adsorption. DR. FOSTSR: above the water, Seme of these are margin plants growing Tne activity vas consity and above the water, but when tho material diced and you pictecd it cut, you had a