April Chapter Meeting

Dr. Jeffrey H. Tepper

April’s chapter meeting speaker will be Dr. Jeffrey Tepper from the University of Puget Sound Geology Department. All are welcome to join us for another exciting virtual presentation!

Title: The ~15,000 Year Environmental History of Lakes in South Puget Sound: From Glacial Retreat to Toxic Algal Blooms

6:30pm Social Hour

7:30pm Talk, followed by Q&A

Registration information will be sent in the April Newsletter.

Abstract

Numerous lakes dot the Puget Lowlands, and many occupy kettles that formed ~15,000 years ago as the ice lobe that occupied this region was melting.  Sediment within these lakes thus preserves a long record of environmental history that includes both natural and anthropogenic changes.  Recent work by UPS faculty and students on lakes near Tacoma (including Gravelly, Waughop, and Spanaway) has revealed surprising diversity in both their “plumbing” (water sources) and their recent (last ~150 years) environmental histories.  Agricultural activity and ASARCO smelter fallout in particular impacted these lakes, but the responses of individual water bodies have varied greatly.  For example, Gravelly Lake has exceptionally clear water whereas Waughop Lake regularly experiences toxic algal blooms.  This talk will describe how we have integrated sediment core analyses, geochronology, and water chemistry to better understand both the past and present day conditions of these lakes.