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

1.  The Bioavailability of Sediment and Dissolved Organic Phosphorus
    Inputs to Lake Tahoe -- Dr. Jerry Qualls

2.  LTIMP Monitoring Protocol Subcommittee Report -- Dr. Alan Heyvaert

3.  Angora Meadow Monitoring and Evaluation as a Filter for Treating
    Stormwater Runoff -- Dr. Michael Johnson (cancelled)

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

**The Bioavailability of Sediment and Dissolved Organic Phosphorus
Inputs to Lake Tahoe -- Dr. Jerry Qualls**

Dr. Qualls presented the results of Joseph Ferguson's research into the
bioavailability of phosphorus in suspended sediments that are
contributed to Lake Tahoe by major tributary streams, from urban runoff,
and from erodable stream banks. The study also began to look at the
bioavailability of dissolved organic phosphorus in tributary streams.
Both algal bioassay and chemical fractionation methods were used to
determine the bioavailable portion of the total phosphorus in the
filtered suspended sediments of samples from the various sources of
input to Lake Tahoe. The algal bioassay consisted of determining the
algal uptake of dissolved phosphorus after a three week incubation of
the filtered suspended sediments with algae (selenastrum capricornutum)
in a P-free algal growth medium by comparing the concentrations of total
phosphorus in solution before and after the incubation. The change in
the total phosphorus concentration in solution after incubation results
from the direct uptake of exchangeable orthophosphate by the algae and
the algae uptake of organic phosphate mineralized by phosphatase
enzymes. The chemical fractionation method is sequential series of
reactions that remove successively less bioavailable phosphorus with
each reaction starting with removing exchangeable phosphorus with anion
exchange membrane, then chemically exchangeable phosphorus (extractable
inorganic and organic phosphorus) with NaHCO~3~, then iron and
aluminum-bound phosphorus (inorganic exchangeable phosphorus) with NaOH,
then humic acid organic Phosphorus (organic extractable phosphorus) with
more NaOH, and finally mostly calcium-bound phosphorus (extractable
total phosphorus) with HCl.

The research determined that the percentage of total phosphorus that is
bioavailable in suspended sediments varies by stream, source, and season
with tributary suspended sediment phosphorus ranging between 3 to 46%
bioavailability, urban runoff suspended sediment phosphorus ranging
between 1 to 43% bioavailability, and erodable stream bank sediments
phosphorus ranging between less than 1 to 16% bioavailability. And that
while the total concentration of phosphorus in the suspended sediment
sources to Lake Tahoe are high relative to values of other studies for
other locations, the percentage that is bioavailable is similar to
percentages found in other studies. Since total suspended sediment
annual loading to Lake Tahoe is low considering the total volume of the
lake, 3709 tones based on tributary monitoring for 2003, the study
concludes there must be other considerable sources of bioavailable
phosphorus to Lake Tahoe (atmospheric deposition and groundwater flux)
that can help account for the loss in clarity. The study also concluded
that NaHCO~3~ extractable total phosphorus is a good indicator for
bioavailable phosphorus. Dr. Qualls can be contacted at:
[qualls@unr.edu](../qualls@unr.edu).

**LTIMP Monitoring Protocol Subcommittee Report -- Dr. Alan Heyvaert**

Alan provided a description of the previous LTIMP effort to provide
monitoring guidance that identifies critical constituents for analysis
and enhances monitoring consistency between projects that is supported
with sufficient references. Substantial progress has been made in
understanding the impacts of critical constitutes on the clarity of Lake
Tahoe and the knowledge and sophistication of monitoring methods since
the current monitoring guidance document was produced in 2002. Alan is
leading the effort to update and refine the LTIMP Monitoring Guide and
is looking for volunteers to help gather the updated monitoring
information that will be professionally compiled into an updated report
by the end of 2006. Please contact Alan at (775) 673-7322 or
<alan.heyvaert@dri.edu> if you would like to be involved with LTIMP
Monitoring Guide update.

**Angora Meadow Monitoring and Evaluation as a Filter for Treating
Stormwater Runoff -- Dr. Michael Johnson (cancelled)**

Unfortunately due to unpredictable road conditions Dr. Johnson was not
able to make it to the March meeting. This presentation will be
rescheduled for a future date.

In Attendance:

Jay Aldean, HDR

Nancy Alvarez, USGS\*

Steve Baglin, Wood Rodgers

Larry Benoit, TRPA

Scott Carroll, CTC

Scott Cecchi, CTC\*

Jeanette DuBois, Kennedy/Jenks

Robert Erlich, Lahontan RWQCB

Vern Finney, NRCS

Jon-Paul Harries, TRPA

Alan Heyvaert, UCD-TERC

Christine Kirick, Wood Rodgers\*

Kate Kowalski, JWA

Michelle Kramer, WET Lab

Jacque Landy, EPA/Lahontan RWQCB\*

Theresa Loope, CTC

Ginger Peppard, WET Lab

Jennifer Quickel, CSLT

Dave Rios, NTCD

Catherine Schoen, USFS\*

Mark Sedlock, CTC

Drea Traeumer, Kennedy/Jenks

Chris Twomey, c2me

Russell Wigart, CTC

Next Agenda\*: