**[Topic List:]{.underline}**

1.  Tahoe Science Consortium: General overview and possible roles for
    LTIMP - Zach Hymanson

2.  Lake Tahoe Atmospheric Deposition: Near shore boat monitoring of air
    quality - Tony VanCuren

**[Topic Summaries:]{.underline}**

**Tahoe Science Consortium: General overview and possible roles for
LTIMP** - Zach Hymanson

Zach gave an overview of the Tahoe Science Consortium's (TSC's)
objectives and organization. The TSC has pledged to "work closely with
the resource management agencies in the basin to provide the best
possible science for policy, management, and regulatory decision
making." To this end TSC has identified an number of primary functions
including: 1) serving as a science and research coordinating entity by
providing: peer review, science consultation and referral, synthesis and
assessment of existing scientific information, 2) develop Lake Tahoe
Basin science plan, and 3) develop adaptive management role. The TSC
consists of the original five research institutions that signed the
August 2005 MOU: Desert Research Institute, University of California,
Davis, University of Nevada, Reno, U.S. Geological Survey, and USFS
Pacific Southwest Research Station. Executive leaders from each of the
research institutions make up the TSC executive committee that oversees
the Committee of Scientists. The Committee of Scientists is made up of
two representatives from each research institution. Zach informed LTIMP
that other research institutions can join the TSC, but must commit to
participate on TSC Executive Committee and Committee of Scientists. Zach
serves as the TSC director, and it is his job to "coordinate and enhance
linkages between the TSC and the resource management agencies in the
basin." TSC also anticipates hiring an administrative assistant. The TSC
is funded with SNPLMA Round 5 and 6 funds. The development of a Science
Plan is part of the Round 6 workplan, and is expected to take 2 years to
complete. The Science Plan will contain research strategies to fill in
the gaps that exist in our current understanding of environmental
processes for the valued resources of the Lake Tahoe Basin. Once a Tahoe
Basin Science Plan is created it will be maintained and updated annually
by an Executive Science Integration Team made up of both Committee of
Scientists members and management agency representatives from the Tahoe
Science Advisory Coordination Committee (TSAC) and the TSC Director.
Zach sees TSC's role as coordinating current and existing science and
research efforts and advising the direction for future science in the
Tahoe Basin, but not controlling science in the basin. In this vein,
Zach applauds the LTIMP's efforts to update the Monitoring Protocol
Guidance document, and sees that LTIMP functions much like a Working
Group (as identified in the Conceptual Model Depicting Interaction
Between Consortium and Resource Management Agencies) in an effort that
will likely provide valuable input to the development of a Comprehensive
Monitoring Plan for Lake Tahoe. The TSC will issue Requests for
Proposals for Science Themes to be funded by SNPLMA Round 7 after the
Science Symposium in October 2006. For more information about TSC
contact Zach Hymanson, TSC Director, at: <Zhymanson@tahoecons.ca.gov>,
or (530) 543-6017.

**Real-Time On-Lake Measurements from the Lake Tahoe Atmospheric
Deposition Study (LTADS)**- Tony VanCuren

Tony began by explaining how this project grew out of an opportunity to
utilize salvaged real-time air monitoring equipment to provide a quick
characterization of atmospheric deposition to Lake Tahoe. Prior to
adding the real-time on-lake measurements, LTADS had been limited to
five fixed-site monitoring stations that did not effectively cover the
spatial diversity of air deposition to Lake Tahoe nor did they include a
monitoring station on Lake Tahoe. The goals of this effort were to
determine: shore zone air flow effects, diurnal variation of flows and
pollutant loads, land-use effects on pollutant loads, area of influence
of shoreline emissions, and to contribute to a conceptual model of Tahoe
Basin circulation. The real-time on-lake air deposition monitoring was
carried out using the Research Vessel Frantz equipped with an instrument
package from UCD/LAWR (Courtesy of Prof. John Carroll, UCD) that
measures concentrations of: NO~y~, O~3~, and particulate matter (PM) 2.5
μm (Optical), with meteorology: residual humidity, air temperature, and
air pressure, and GPS, and data logging (3-second integration) support.
The instrument package also included a CLIMET CI 500 Particle Counter
that provided 1-minute integration of particle counts in the following
size ranges (in μm) :0.5-1, 1-2.5, 2.5-5, 5-10, 10-25, 25+. The intake
for the instruments was mounted on the bow of the boat, 2 meters above
the Lake surface.

Three different monitoring routes were followed, two for characterizing
am and pm slope flows at both the north and south shores, and one north
to south transect. The North Shore pm route (Tahoe City to Incline
Village, then back to Tahoe City along shore) showed that NO~y~
(products of high temp combustion, typically from motor vehicles) is
fairly evenly distributed in the open lake. The evening monitoring route
(from 8 pm to midnight) showed that air pollutants accumulated in the
airshed are brought downslope and the concentrations increase where
there is near shore population density and roadways. The morning routes
show higher levels of particulate matter and lower concentrations of
NO~y~ until morning activities begin around 5:30 am, when combustion
products peak followed by an increase in particulate matter at 6:00 am.
The second day of the North Shore route coincided with the Chester Fire
(7/10/2003), which resulted in higher background concentrations of NO~y~
and PM that were still lower than measured in-basin sources. A
comparison of evening and morning routes shows that the highest
concentration of PM in the range of 10 to 25 μm and that significantly
more comes from active urban shoreline than from undeveloped or
residential shoreline. A stationary air monitoring location at the North
Shore U.S. Coast Guard pier showed a temporal pattern to PM deposition
that has diurnal concentration peaks centered around morning (4 to 8 am)
and evening (5 to 9 pm) rush hours. The North to South transect provided
insight to regional transport of ozone (indicates aged air) which is
reduced by reaction with local sources of NO~y~. Monitoring results
suggest that western regional transport of ozone is captured in the
Tahoe Basin by evening downslope air flows until inversion sets up
(stable stratified temperature air layers that prevent mixing with
regional western flow that travels over the inversion) then local
sources of NO~y~ react with and reduce captured ozone, until inversion
breaks in the morning and then the ozone concentration gradually
increases to evening peak. The North to South transect route also showed
stable and well mixed PM on the west shore with South Shore spikes. The
South Shore morning and evening route supported the findings of the
North Shore route, that near shore development and activity generate
greater concentrations of NO~y~ and PM. The on-lake air monitoring also
indicates that the zone of impact from local sources is the shore zone,
just like with near shore turbidity monitoring, and there are no
cross-lake air quality impacts.

Analysis of the real-time on-lake air quality monitoring produced the
following conclusions: night and morning downslope flows deliver gas and
particle pollutants to the near-shore zone of Lake Tahoe, near-shore
concentrations are strongly related to shoreline land use and activity
patterns, mid-lake concentrations are weakly affected by shoreline
emissions, midday lake breezes disrupt shore-zone to lake transport,
local sources dominate PM \> 2.5 μm and peaks of all PM lake-wide,
regional transport controls ozone and significantly influences PM 2.5 μm
and smaller lake-wide, and transport is unevenly distributed in the
Tahoe basin. The results of the real-time on-lake air quality monitoring
will be documented in a chapter of the LTADS report that is expected to
come out soon. For more information, please contact Tony VanCuren at:
<rvancure@arb.ca.gov> or (916) 327-1511

In Attendance:

Nancy Alvarez, USGS- WRD

Scott Brown, NTCD\*

Scott Cecchi, CTC

Jason Drew, Nichols\*

Jena Green, USGS

Alan Heyvaert, DRI\*

Christine Kirick, Wood Rodgers\*

Kate Kowalski, JWA

Jack Landy, EPA/Lahontan RWQCB

Derek Norpchen, TRPA\*

Dave Rios, NTCD\*

Catherine Schoen, USFS\*

Andy Smith, WET Lab

Chris Twomey, c2me

Tony VanCuren, CARB

Rita Whitney, TRPA

Brent Wolfe, nhc

Next Agenda\*: