Spatial and temporal patterns of nearshore clarity in Lake Tahoe from fine resolution turbidity measurements

Figures & data

Figure 1 Location of the South Lake Tahoe, CA, study area.

Figure 2 Nearshore area by the City of South Lake Tahoe. The locations for the turbidity transects at distances of 0.5 and 1.0 km from the shore (marked with a bold line) are shown by dashed lines. The large black dot marks the location approximately 250 m offshore from the outlet of the Upper Truckee River where water samples were collected for particle composition analysis.

Figure 3 Transects of turbidity at 0.5 and 1.0 km offshore along 3.5 km between the outlet of the Upper Truckee River outlet and east of Bijou Creek South Lake Tahoe for 5 dates (see Fig. 2 and Table 1).

Figure 4 Upper Truckee River discharge recorded at the US Geological Survey gage (station number 10336610) in South Lake Tahoe (top). Distance in a perpendicular direction from the lakeshore where elevated and high turbidity values were recorded (bottom) during the study period July 2002–August 2003.

Table 1 Weather conditions preceding the 5 survey dates that were selected to exemplify typical, calm fall conditions, spring precipitation events, spring snowmelt, and calm summer conditions. This is a subset of the 23 surveys conducted in 2002 and 2003.

Date	Preceding Hydrologic Conditions
22 October 2002	Calm, fall
19 March 2003	Two days after lake-level rain
9 April 2003	Snow at lake level, then wind, snow melting as survey completed
22 May 2003	Calm weather, close to the peak of spring snowmelt runoff
7 July 2003	Calm summer conditions, no rain for several days

Figure 5 Particle composition from water samples collected approximately 250 km offshore South Lake Tahoe (see Fig. 2) on 5 dates described in Table 1. Samples composed of up to 25% silica and 75% carbon were considered organic material, while samples composed of 10% metals were of mineral origin. Seasonal circles were derived from the full set of 14 samples collected at this site. For clarity, only the samples from the dates in Table 1 are shown.