August 2022 - Page 10

A GUIDE TO SEASONAL LAKE SURFACE COATINGS

By : Eric Roberts , Friends of the Lake
We cannot expect our lakes to be as clear as Crater Lake in Oregon ( pictured above ). Whereas our lakes are dynamic and quite hospitable , Crater Lake is in a particularly harsh environment for aquatic life . When taking a brief dip several weeks ago ( in early July ), Crater Lake was an icy 53 degrees ; Nightingale Beach concurrently had a water temperature of nearly 80 degrees . It lies atop the Mount Mazama caldera , nearly 6,200 feet above sea level , and receives 42 feet ( yes , feet !) of snowfall every year . The lake has no inlet or outlet streams , whereas streams in our community constantly bring in sediment and algae nutrients . At 1,943 feet deep , Crater Lake is the deepest lake in the United States and one of the deepest in the world . The deepest part of Lake Linganore , by contrast , is only about 37 feet deep . If it weren ’ t for the fish stocking that took place in the late 1800s & early 1900s , there would be no fish in Crater Lake .
No , the environment for our lakes is much more favorable to aquatic life . Lake water surface coatings , reduced water clarity , and olive hues are manifestations of abundant life . The coatings become particularly evident when the air and water are still . Many not only find these naturally occurring scums uninviting but sometimes alarming . We often wonder what the scums are and what they might be signaling .
The surface scums you may see on our lakes are most likely harmless evidence of a flourishing biota . However , some lake water scums ( e . g ., cyanobacteria ) can be harmful . Therefore , you should avoid contacting lake water scums , and your pets should be kept away . Distinguishing between various coating is not straightforward ; therefore , the prudent approach is to avoid contacting lake water scums and keep your pets away .
POLLEN
Accumulations of pollen from trees and other sources appear algae-like . Pollen forms a film on the water , but unlike algae , it is frequently yellowish and will feel coarse to the touch rather than slimy . When pollen is abundant , it coats items on land ( e . g ., shore rocks ) and in the water . Pollen most often accumulates on the surface of our lake waters in spring and early summer .
When you run a stick through pollen-covered water , the green , yellow or white material will break apart . That doesn ’ t happen with algae . Instead , the tiny planktonic algae remain suspended in the water , while the filamentous algae can actually be caught and pulled out .
10 LakeTalk August 2022