Bijou Park Creek Stream Environment Zone Evaluation
South
Lake Tahoe, CA USA July 2003
Tahoe-Baikal Institute Exchange Participants
Will Bettmann (USA)
Melissa Haeffner
(USA)
Irina Moiseeva
(Russia)
Marilyn Phelps (USA)
Evgeniya Skur`yat
(Russia)
Interpreter—Ariadna
Reida
Project Sponsors
CA Tahoe Conservancy:
Kim Carr
Tahoe Research Group:
Dr. Alan Heyvaert
Project Leader
Bryan von Lossberg
Project Coordinators
CA Tahoe Conservancy:
Heather Kuykendall
Northwest Hydraulics:
Ed Wallace, Andrey Shvidchenko
Tahoe Research Group:
Andrea Parra
City of So. Lake
Tahoe: Abe Haen
The Tahoe-Baikal Institute (TBI) collected
and analyzed necessary data for the preliminary project planning and design of
the Bijou Park Creek Stream Environment Zone (SEZ). This project area is a part
of the larger East Pioneer Trail Erosion Control Project initiated by the
California Tahoe Conservancy (CTC) and the City of South Lake Tahoe (CSLT). It
is characterized by uncontrolled runoff through the City rights of way, private
property and public parcels. The Bijou Park Creek SEZ is located in the
southeast portion of South Lake Tahoe. The SEZ runs northwest into the lake,
paralleling Blackwood Rd and crossing Ski Run Blvd just north of Needle Peak
Rd. The project area boundaries are roughly: Highway 50 to the north, Saddle Rd
to the south, Wildwood Ave to the east and Blackwood Rd to the west. The survey
of this SEZ was conducted to perform an Existing Conditions Analysis by
identifying pollutant sources, drainage facilities and outfall locations.
Opportunities and constraints for source control, infiltration solutions, water
quality treatment systems and SEZ restoration were identified for future
planning and design. Both primary and secondary sources were implemented in
this evaluation. Using survey equipment and GPS technology, participants
determined the shape of channels relative to the floodplain (channel
morphology), recorded the velocity of the flow and mapped cross-sections of the
streambed. Observation methods were used in assessing land use, soil and
vegetation patterns of the area. Pre-existing resources included aerial
photographs, topography maps and parcel ownership data. In addition, a
literature review provided a historical perspective of changes in the area. The
three main recommendations to improve this SEZ are: 1) reduce impervious
surfaces by eliminating and narrowing roads 2) mitigating human disturbance
through BMPs and community involvement and 3) SEZ restoration. TBI participants
along with project coordinators from CTC, CSLT, Tahoe Research Group (TRG) and
Northwest Hydraulics (NHC) surveyed the area between June 26-July 13, 2003.
Background
It has been well documented by the UC Davis
Tahoe Research Group (TRG) that, during the last four decades, Lake Tahoe has
been losing one foot of its internationally famous clarity per year. Declining
clarity is attributed to the combined effects of suspended sediment
concentration and nutrient loading caused by urbanization and subsequent
erosion problems. Development has encouraged Stream Environment Zone (SEZ)
encroachment and increased the proportion of impervious surface (e.g. roads,
parking lots), which diminishes water infiltration rates. But to imply that
watershed disturbance is a modern phenomenon would be a mistake. Instead, a
railroad designed to transport lumber through our site was built as early as
1860 and was immediately torn up after resources were exhausted. This route
would later become Highway 50.
This fact gives evidence that there is hope.
Erosion caused by clear-cutting during the late 1800s also sent a large amount
of sediment pouring into the lake, but the lake did recuperate with time. One
unfortunate difference between then and now, however, is that logging was a
pulse disturbance, a one-time event, while urbanization is a chronic
disturbance. A full recovery such as that which occurred after logging is
unlikely as Lake Tahoe’s population increases. Paleolimnological research
concludes that if this situation is not alleviated in the next 20-30 years, the
effects on clarity can never be reversed.
(Heyvaert, 2003).
In an effort
to beat the clock, the California Tahoe Conservancy developed the Erosion
Control Program (ECP) as one of six programs focused on Lake Tahoe. Over the
past 18 years, the ECP has contributed over $62 million and 93 projects
throughout the Tahoe Basin. CTC standards for assessing watersheds now dictate
that an overall picture of the area must be detailed before improvements are
implemented. In the past, agencies in the Tahoe Basin focused solely on problem
areas. The projects did not address treating pollutants at the source where
they might be mitigated before becoming an expensive problem. To do this, the
CTC prefers to return watersheds to their previous, natural state to treat
runoff, before installing equipment at outfalls.
Goals of Project
The CTC’s Erosion
Control Program, of which this project is a small part, is a comprehensive
program which aims to:
Ø reduce the sources
of soil erosion,
Ø stabilize the
movement of runoff, and
Ø establish areas to
filter out sediment and nutrients while restoring natural marshes and meadows.
SEZs throughout the
Basin play a critical role in multiple water quality and clarity preserving
functions, and thus are an important consideration in any erosion control
project. The CTC works with various
agencies, including the City of South Lake Tahoe, to implement erosion control
and SEZ protection and restoration projects in the basin. The goals of the TBI project were to:
Ø collect and analyze
field data,
Ø perform existing conditions analysis,
Ø identify pollutant sources, drainage facilities, outfall
locations,
Ø recommend future planning and design, and
Ø identify opportunities and constraints for source control,
infiltration solutions, water quality treatment systems and SEZ restoration.
This project area,
including 4 square miles, encompassed several Environmental Improvement Program
(EIP) projects. The project is in the
conceptual planning stage with construction expected in 3 to 4 years. A similar project was conducted with the
2002 TBI group in the Sierra Tract residential and commercial area. The data that the team collected, inputted,
and analyzed has already been put to use in public meetings, in prioritizing
specific problem areas, and for planning of the Sierra Tract erosion control
project. Similarly, the 2003 project
will be used in planning and designing an erosion control project.
We spent time in
the field conducting land-use and drainage surveys to accurately assess a
particular SEZ’s current conditions, as well as how it has changed over the
last century. This included:
Ø measurement of the
SEZ’s physical dimensions,
Ø description of
property and land use characteristics and conditions along the SEZ, and
Ø evaluation of the
drainage area’s vegetative conditions.
Additionally, we
spent time:
Ø photographing the
project area,
Ø estimating
impermeable coverage in the drainage area,
Ø characterizing
possible erosion problem areas, and
Ø analyzing historical
documents, aerial photographs and topographic maps.
Each team also
spent time at the CTC inputting and analyzing the data with GIS and Excel.
We evaluated the Bijou Park
Creek for stream flow paths as well as disturbances which might result in
decreased infiltration and increased expulsion of sediments, nutrients and
pollutants from Bijou Park Creek into Lake Tahoe. In our evaluation of existing conditions and data collection for
the disturbed Bijou Park Creek SEZ, we used survey equipment and GPS units to
record the position, velocity, and cross-sections of the creek. Land use and vegetation patterns of the area
were assessed. Other sources we examined included aerial photography,
topographic maps, parcel ownership data, and a literature review of historical
information. In our historical analysis
of the Bijou Area we studied topographical maps and aerial photos over time
(mid-1800s–present) and noted any changes in our SEZ. We noticed significant human influence in the project area as
early as the mid-1800s, and lasting over 160 years. This analysis was combined with research of historical literature
for the area, and the following timeline of events was created.
Starting in the 1960s water clarity loss documented at ~1 foot per year
An examination of Aerial Photos over several years for
the area shows us a great deal about the pattern of development in the
SEZ. A 1940 US Forest Service digital
ortho quad (DOQ) shows an established road network but minimal SEZ
disturbance. A 1968 photo of the same
area shows significant development and disturbance added throughout. A 2000 USFS photo shows development patterns
have been significantly slowed by new regulations, in fact there is little
change from the 1968 photo; however, there is continued encroachment on the
SEZ.
We were also charged with the task of suggesting
potential projects to improve the Stream Environment Zone with the ultimate
goal of reducing the amount of sediment, nutrients and pollutants that leave
the Bijou Park Creek SEZ and enter Lake Tahoe.
Accompanying pictures of these suggested projects can be found in the appendix. This list of suggestions runs from the
downstream end at the Super 8 Motel to the upstream end before the Heavenly
parking lot. First we suggest the
elimination of the run-down Super 8 conference center and associated
pavement. The conference center is
dilapidated and seems to be rarely used.
The overflow parking lot, under which the stream is piped, also seems to
be rarely used, even in the peak of summer.
Removing these impervious areas would allow a possible restoration of
the SEZ from pipe to above-ground condition in this area and provide a spot for
a natural or underground treatment basin.
Also, we noticed people parking
adjacent to the Super 8 parking lot off of the paved areas (we noticed this all
through the area). This practice leads
to an increase in impervious area due to compaction and subsequent erosion, as
well as an increased release of sediment into the impervious flowplain which
leads directly into Tahoe. We suggest
that such volunteer parking areas be revegetated and bollards be added to
prevent parking. The last suggestion
for the Super 8 property includes management practices for the drop inlets on
their property. Both drop inlets we
observed were trash-filled and near potential pollution sources, one
immediately next to the Super 8 Dumpster and the other adjacent to the ad hoc
parking and sediment source mentioned earlier.
These would be prime sites for treatment and prevention of trash getting
into the inlet which travels untreated under the Super 8 & Highway 50 into
Tahoe.
Moving upstream from the Super 8, we observed several
streets that were excessively wide for the traffic and parking we
observed. These were streets directly
over the stream and floodplain. It
seems that many of these roads were built and sized with the intention or
expectation of much more development than could take place following
regulations of the 1970s & 80s, and turned out to be unnecessarily
wide. These extra impervious areas
downstream are especially important since it seems to be the area of greatest
disturbance. We found several
opportunities to reduce the impervious area (road cover) and expand the area
for the stream and floodplain. First, we suggest converting Bill and Shirley
Streets (and possibly others) to a one-way street network. With a one-way street network on some of the
residential streets, the streets could be narrowed by 1/3 to 1/2 and revegetated to allow greater
infiltration.
Our next suggestion concerns a Seventh Day Adventist
Church on Werner Salas built directly in the floodplain. Reducing their parking lot would address at
least some of the SEZ encroachment, but we found that the church and other
buildings along Werner Salas all also have street access along Vanda Lee
Street, making Werner Salas unnecessary as an access point. Furthermore, the day care center next to the
church could share one parking lot with the church since they have opposite
schedules (the church operates Saturdays and the day care
Mondays-Fridays).
Further up our evaluation zone, into reach four (near Ski
Run and Needle Peak, under which our stream is piped), we found some other
areas which may be causing problems with our SEZ. At a condo complex along Ski Run above Needle Peak we observed
significant erosion from unvegetated bank carrying sediment, nutrients and snow
removal remnants into Ski Run, and from there into SEZ. Across the street a concrete sediment basin
appeared to be full of built-up sediment and we suggest replacement of the
bottom of this concrete sediment basin with a permeable surface in order to
allow more infiltration. We could
possibly remove the concrete basin entirely in conjunction with a narrowing of
Ski Run Boulevard. Our major suggestion
in this area concerns Ski Run Boulevard itself. The street is eighty feet wide with a twenty-foot
right-of-way. The street is
significantly oversized for the amount and type of traffic it receives, again
apparently as a result of unfulfilled development expectations in the 1950s. A
width reduction would actually not be an extreme proposal. There is a current project active below
Pioneer Trail along the length of Ski Run to narrow Ski Run from Pioneer to
Highway 50 by half and create two Class One bicycle trails on the removed area
and fill the remainder with vegetation.
The area from Highway 50 to Pioneer on Ski Run is much more heavily used
than the portion of Ski Run we are discussing, and thus claims for traffic
necessitating the width of the northern end of Ski Run are unfounded. Additionally, maintaining the aesthetics of
the street would require a continuous width and planning pattern for the entire
run. This street width reduction would
reduce impervious coverage and allow an additional bike path and pedestrian
walkway to be constructed.
The last section of our suggestions concerns not only
impervious area removal but infiltration assistance through the installation of
treatment basins, both natural and engineered, at key points along the SEZ.
First, the northeast corner of Ski Run and Needle Peak drains steeply into an
unvegetated depression, and there is much visible erosion at the site. The problems combined with the current
topography make this area ripe for a natural treatment basin and revegetation
of the steep banks draining into it.
Another possible location for a treatment basin would be on Charlesworth,
a cul-de-sac with only one home built on it.
We suggest reducing the unnecessarily large paved area, including the
bulb of the cul-de-sac and half of the road leading to the bulb (leaving an
access strip for the one house). This
area is currently flat, surrounded by higher SEZ, and would be another
potential site for a treatment basin.
We came to several conclusions based on our
research. First, it is clear that the
majority of development occurred before environmental regulations were enacted
(1940-1970s). Consequently, much of the
development occurred in or near the Bijou Park Creek watershed, developments
that would not be possible under current regulation. A great deal of remediation is required in order for the SEZ to
function anywhere near its potential.
Not only is the SEZ unable to filter sediments and nutrients adequately,
it also poses a flood threat to a number of structures built in the
floodplain. From our research and
observation, natural wetlands are the best single source of infiltration and
are, therefore, the ultimate goal of SEZ restoration, wherever possible. Another point worth noting is that the SEZ
originates in the vicinity of the Heavenly Ski Resort, which includes a large
impervious area (parking lot) linked to (oversized) Ski Run Blvd. These combined impervious areas are a
potentially major source of sediment and nutrients to the SEZ and Lake
Tahoe. In addition, road
salting/sanding/volcanic ashing of the roads and parking lots after snowfalls
provides a significant source of sediment.
The CTC (and other organizations) are trying
out new assessment methods with this project.
Instead of looking solely at problem areas , they are placing the focus
on the entire watershed. This approach makes sense in terms of
identifying solutions that are less likely to cause problems in the
future. This method of looking at the
whole picture could be taken a step further by adding a sociological
component. The whole reason for ECPs
(Erosion Control Projects) is to mitigate human impact. Therefore, studying human relationships to
their environment is necessary for identifying ways in which
people currently interact with the environment
and ways they might be influenced (persuaded) to take better care
of the environment. For example, a simple survey of our project
area may reveal that the majority of residents are Spanish-speaking
renters. Knowing that BMPs are directed
specifically towards property owners (and at the time of writing there are no
Latinos on the TRPA Board of Directors), this may give us a clue to reasons why
residents of that area might not have heard of BMPs or care about them. Another study may reveal that many families
live in that area and regularly use the SEZ for recreational activities.
By and large we met the original goals set
for our project. Our project could have
been improved by additional time to provide more detailed GIS analyses and by
using more advanced survey equipment in order to refine our stream delineation
even further.
To expand upon the findings of our project,
future TBI groups or other researchers might conduct a chemical and sediment
assessment of the different reaches of the stream in order to compile a more
point-specific assessment of the sources of pollution and sediment at points
throughout the stream. Additionally,
pre- and post- assessment of these levels would be advised if any of the
suggested remediation projects are adopted.
Works Cited
2003. Hayvaert, Dr. Alan. Paleolimnological
Reconstruction of Baseline Conditions and Ecosystem Response to Anthropic
Disturbance in the Tahoe Basin. Presentation.
June 26 South Lake Tahoe, CA.
1993. Scott, Edward B. The
Saga of Lake Tahoe, Vol 1 and 2. Sierra-Tahoe Publishing Co. Pebble Beach,
CA.