Yellowstone National Park Report
This study was initiated in 1982 to critically evaluate the evidence (Varley 1974, Shero and Parker 1977) that primary productivity in Yellowstone Lake has decreased during the last 1500 years with an accelerated decline in the last century.
Romme, W. H. and Knight, D. H.
"Yellowstone Lake: An Evaluation of Patterns in Productivity,"
University of Wyoming National Park Service Research Center Annual Report: Vol. 8
, Article 23.
Available at: http://repository.uwyo.edu/uwnpsrc_reports/vol8/iss1/23