New data released by the Tahoe Regional Planning Agency (TRPA) and the University of California, Davis revealed that the water of Lake Tahoe has earned an average annual level of clarity at 77.8 feet for 2014, its biggest improvement in over a decade.
The figure represents the depth at which a special white disk called a Secchi disk, when dropped into the lake, remains visible underwater.
The data was gathered by researchers from the UC Davis Tahoe Environmental Research Center, whose study of the lake has spanned the last half century.
Researchers attributed the improvement to the four-year drought and also the continued effort to restore the environment, which included wetlands restoration and erosion and runoff control in the Tahoe Basin.
The reduced precipitation brought on by the drought resulted in a decrease in the level of contaminants that flowed into Lake Tahoe. This became more evident during the summer, when researchers recorded clarity levels to be at their highest since 2002.
This long-term trend in recording summer clarity has been deemed a complex procedure. Several factors, such as the amount of precipitation found in the basin and the depth to which the lake mixed the previous winter, had to be considered.
The Lake Tahoe Environmental Improvement Program, for the past two decades, had so far been successful in spearheading project investments both from the public and private sectors. All are aimed at improving water quality, including other environmental indicators around Lake Tahoe. While the TRPA tracks at least a hundred of these measurements, it is still important to note the significance of mid-lake clarity as a key indicator that would help determine if the restoration programs are indeed producing the desired results.
"These findings underscore that our collaborative efforts to reduce erosion and stormwater pollution in the Lake Tahoe Basin are working and have halted the decline in mid-lake water," said Joanne Marchetta, TRPA executive director.
While it is true that the average annual level of clarity for the previous decade showed bigger improvements than the preceding one, it is still far from the desired clarity restoration level of 97 feet predetermined by the state and federal regulators. The highest value recorded was 93.5 feet on Jul. 7, 2014 while the lowest was 57.4 feet on Sept. 16, 2014. Throughout that year, 28 individual readings were taken, which yielded the average clarity level of 77.8 feet.
"While these latest data are very reassuring, they should not be interpreted as victory in our joint restoration efforts," said Geoffrey Schladow, director of the UC Davis Tahoe Environmental Research Center.
Photo: Chris Yunker | Flickr
