2017 STOL

No Project associated with this Finding

Finding Details

The utility of the Nearshore Network can be demonstrated using turbidity, a measure of the cloudiness of the water caused by the presence of fine particles. The water quality standard for turbidity at Lake Tahoe is 1 NTU, except in the vicinity of stream mouths where it is 3 NTU. Using turbidity measurements from the Nearshore Network together with a model of wind-generated waves, graduate student Derek Roberts and his Chilean collaborator Dr. Patricio Moreno were able to make estimates of wave-induced turbidity at any point around the shoreline.The results showed that turbidity at the measurement point varies considerably around the lake, largely in response to the exposure to prevailing winds (from the westsouthwest). There was also considerable variability between seasons.

Most importantly the results showed how frequently a particular turbidity value is exceeded in the nearshore region due to waves. The colored dots around the shore indicate the percentage of time that turbidity exceeds the standard of 1 NTU at a depth of 7 ft near the lake bed. For example a pale green dot indicates that the standard was exceeded 25% of the time in a given season. It is evident that the eastern shore, because of its exposure to winds, has the highest number of exceedances, particularly during the Fall cooling period from October-December. If we look at the results for 10 NTU, exceedances occur less often, but they are still surprisingly high. For example, there are numerous sections of the shore where 10 NTU is exceeded near the bed for more than 20% of the time in certain seasons.

For additional details see:

2017 State of the Lake (UC-Davis)