End of show
Near Shore Studies
Ken TaylorRick SusfalkMargaret Shanafield
Desert Research Institute
Funding provided by:
Nevada State Lands (Tahoe license plates)
California Lahontan Regional Water Quality Control Board
TRPA
Near shore zone:
Fast and local response to land use changes.
C
larity: greatest depth a Secchi disk is visible
turbiditychlorophylltemperature
Sample inlet is1 foot below surface
End of show
Snapshot DayMay 10, 2003
InclineKingsBeach
Star Harbor
Emerald Bay South
Shore
End of show
Cebta distance profile
End of showTahoeKeys
UpperTruckee
BijouCreek
StateLine
SkiRun
July 112002
Calm
Edgewood
Oct 222002
Calm
TahoeKeys
UpperTruckee
BijouCreek
StateLine
SkiRun
Edgewood
Nov 132002
2 inchsnowonshore
TahoeKeys
UpperTruckee
BijouCreek
StateLine
SkiRun
021218
Dec 182002
Calmandcold,Keysfreeze
TahoeKeys
UpperTruckee
BijouCreek
SkiRun
030108
Jan 082003
2 feetof snowonshore
TahoeKeys
UpperTruckee
BijouCreek
SkiRun
Jan 202003
Calm
TahoeKeys
UpperTruckee
BijouCreek
StateLine
SkiRun
Edgewood
Jan 292003
2 daysafter rain onlakeshore snow
TahoeKeys
UpperTruckee
BijouCreek
SkiRun
Jan 292003
6 daysafter rain onlakeshore snow
TahoeKeys
UpperTruckee
BijouCreek
SkiRun
Feb 172003
After 4 inchsnow onshore
TahoeKeys
UpperTruckee
BijouCreek
StateLine
SkiRun
April 52003
calm
TahoeKeys
UpperTruckee
BijouCreek
StateLine
SkiRun
Edgewood
April 192003
Afterlakelevelrain
TahoeKeys
UpperTruckee
BijouCreek
StateLine
SkiRun
April 42003
After6 inchsnow onshore
TahoeKeys
UpperTruckee
BijouCreek
StateLine
SkiRun
May 13,2003
Calm,spring run off
TahoeKeys
UpperTruckee
BijouCreek
StateLine
SkiRun
May 222003
Calm,springrun off
TahoeKeys
UpperTruckee
BijouCreek
StateLine
SkiRun
June 52003
Calm,end of run off
TahoeKeys
UpperTruckee
BijouCreek
StateLine
SkiRun
June 242003
After rain
TahoeKeys
UpperTruckee
BijouCreek
StateLine
SkiRun
Edgewood
July 032003
calm
TahoeKeys
UpperTruckee
BijouCreek
StateLine
SkiRun
Edgewood
Collect particlesample on 0.1 micron filter
Examine with scanning electron microscope
Boat photo 1 micron
UpperTruckeeoutlet
Organic
Boat photo
SandHarbor
1 micron
Mineral
End of show
Elemental composition ofparticles off Bijou Creek
End of showTahoeKeys
UpperTruckee Bijou
Creek
StateLine
SkiRun
Edgewood
Algae
Minerals
End of showTahoeKeys
UpperTruckee Bijou
Creek
StateLine
SkiRun
Edgewood
Highest turbidity
Near Shore Zone
Only a few areas have a problem.
Mineral particles from some, but not all, developed watersheds are the biggest problem.
Near Shore Zone
Biggest problems occur during lake level snow melt and spring run off.
How can we keep the small mineral particles out of the lake?
Littoral Zone Turbidity Threshold
1 NTU (Secchi clarity of ~4 m) away from streams
3 NTU (Secchi clarity of 1 to 2 m) for areas influenced by a stream.
Is occasionally exceeded.Insignificant protection for lake.
near shore zone clarity monitoring program is the ONLY way to determine the effectiveness of management actions on near shore clarity.
Near Shore Zone Clarity
A near shore zone clarity monitoring program is the ONLY way to determine the effectiveness of management actions on near shore clarity.
Monitoring
Identify location of problem areas to focus management actions.
Determine trends to evaluate effectiveness of management actions.
Whole lakeshore surveys in winter, spring and summer, to identify locations and spatial extent of problem areas. (Use the boat)
Continuous measurement of major problem areas (7 to 10 areas), to determine temporal trends. (Use moored instruments)
Current Near Shore Monitoring:
• 4 times a year
• Calm conditions
• 9 locations
• Water depth of 25 m
Cannot identify problem areas or trends.
But… There is no near shore zone monitoring program.
Mineral particles, not algae, is the biggest problem.
Suggested Monitoring
Whole lakeshore surveys, to identify locations and spatial extent of problem areas.
Continuous measurements, to determine temporal trends.
Near Shore Conclusions
Several problem areas, caused by mineral particles from developed areas
Ineffective regulatory threshold
No way to determine effectiveness of management actions or trends
End of show
Report is available at:
http://tahoenearshore.dri.edu
Lake level snow melt greatly increases turbidity of near shore waters by adding mineral particles to lake.
Upper Truckee, Bijou Creek, Ski Run