UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

                            REGION IX
                        1OO CALIFORNIA STREET
                    SAN FRANCISCO. CALIFORNIA 94111
To Whom It May Concern:

     In a November 6, 1974 letter to EPA, the Council on
Environmental Quality requested the preparation of a supple-
ment to the Final Environmental Impact Statement (F-EPA-24005-
6A), Wastewater Treatment and Conveyance System, North Lake
Tahoe-Truckee River Basin, (Tahoe-Truckee Sanitation Agency).
This supplement was to discuss various unresolved environmental
issues which remained within recognized technical issues that
were identified in the final impact statement prepared by EPA,
Region•IX.

     A period of 30 days, commencing with the publication in
the Federal Register of this supplement's receipt by CEQ,
will be initiated for your review and comment on the enclosed
supplement.  Each of the six environmental issues raised by
CEQ precede EPA's response.  Also, included as a seventh issue,
is a brief summary of what appeared in the November 1974 Hydro-
geological Investigation of Land Disposal of Reclaimed Waste-
water ^Near Truckee, CA.  Any comments made should be directed
to Mr.  Paul De Falco, Jr., Regional Administrator, U.S. Environ-
mental Protection Agency, 100 California Street, San Francisco,
CA  94111.  In addition, please forward a carbon copy of any
comments on the supplement to the Council on Environmental
Quality, 722 Jackson Place, N.W., Washington, DC  20006, attn:
William Matuszeski.

                              Sincerely,
                            C*. fywUW j^&+*~+
                              Paul De Falco, Jr.
                              Regional Administrator

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                           Comment

J.   Land Use

     a.   EPA has stated that the  sewer  system sizing
     project 4.4 noŁ b built to reach that ultimate design require.
     clarification by EPA.  It  i&  unclear how  the population
     data pre&ented, which i& ba&ed  on the  California V-150
     methodology ^or projections,  i& con&i&tent with applic-
     able growth policies &or the  service area.  In thi&
     regard, the fiinal EIS should  present evidence oft contact
     and discussion with appropriate local  and regional land
     use agencies concerning the size  and timing OjJ facilities
     as they relate to both current  population and ultimate
     design year population.  Any  deviations in population
     projections  (up or down) firom a continuation otf past
     growth rates in the service area  should be explained.

R-la.  The study area represents a portion  of  the California
Sierra-Nevada Region and includes  large  portions of Placer and
Nevada Counties as well as a small area  of  El  Dorado County.
A total of about 380 square miles  is included,  characterized
by a relatively small degree of development.  Existing acre-
age and land use category breakdown  may  be  found on pages 49
through 52 in the Amended Project  Report.  (1)   Land uses for
those portions of Placer and Nevada  Counties within the
North Lahontan Basin are obtained  from surveys conducted by
the California Department of Water Resources,  (DWR).

     Land use projections for Placer and Nevada Counties,
1970 through 2000, are listed in Table 43,  page 254 of the
Environmental Impact Assessment. (2)   These same projections,
plus those for El Dorado County, may be  found  in Table 12-5
of the latest North Lahontan Basin Plan  (3)  of the State Water
Resources Control Board  (SWRCB).  The  DWR land use projections
have been compared with county  land  use  projections,  and no
major conflicts have been found.

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                               -2-
     The  long-term  trend  in  land use within  the  project  area
 is  towards more urbanization; however,  the general  nature of
 the area  will not change  significantly  over  the  next  30  years
 since about  83 percent of the study area consists of  isolated
 wilderness composed of rugged mountains, forests, and plains.
 The greatest projected changes  in  land  use will  occur primar-
 ily in the urban land category.  Currently,  only minor amounts
 of  land are  used for industrial purposes.  Future increases
 will be limited to  that required for light industrial pur-
 poses.  No growth is anticipated for heavy industry.

     Because over three-fourths of the  project area is general
 forest and because  of the climatic and  geographic conditions,
 recreational attractions  result in a small permanent  popula-
 tion being swelled  in the summer months and  in the  peak  weeks
 of  the skiing season by a much  larger seasonal and  recrea-
 tional population.

     Population projections used in determining  eligible
 capacity  for California projects are based upon  State Depart-
 ment of Finance (DOF) projections disaggregated  to  service
 areas by  the SWRCB  in accordance with Section 2133  of the
 California Clean Water Grant Program Regulations. (4)  While
 the  DOF does not project  population for cities or unincorpo-
 rated areas, it does so for counties.  The methodology used
 to determine the portion  of the total project to be supported
 by Federal and State grant funds is explained in detail  on
 page 82 of the Environmental Impact Statement (EIS).  (5)

     As with all grant assisted projects throughout the  State
 of California, grant participation in the construction of the
 project is determined pursuant to these regulations which
 limit grants to interceptor capacity projected 20 years  from
 the  start of construction and treatment facilities  to  10 years.
 These regulations provide that the 20-year population  projec-
 tion shall be based on the most current data of the DOF  and
 DWR.  A 1970 baseline population is established and then a
 percentage growth rate is applied to the baseline.

     Since the 1970 census is an unreliable measure  of
population in seasonal resort destination areas,  the base
population for the Tahoe-Truckee Sanitation Agency  (T-TSA)
project was derived from various sources of information
including house counts,  visitation data, building permit
information,  etc.   The base year 1974,  therefore, is related
to an actual  on-the-ground situation,  both in terms  of popu-
lation,  population equivalents,  and wastewater flows.   In

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                               -3-


 order to establish an accurate baseline population which
 includes seasonal, recreational and day use,  the State Board,
 Environmental Protection Agency (EPA),  and the applicant
 reviewed the most recent data provided  by the Nevada County
 Planning Department,  local county water districts, the U.S.
 Forest Service,  California Department of Parks and Recreation,
 and the Tahoe Regional Planning Agency  (TRPA).

      The projected populations are derived from statistical
 demographic trends, and are not related to a  future on-the-
 ground situation.   Consequently,  they are not related to
 growth policies  of local governments, and are not related to
 future land use  patterns or densities.   While grant applicants
 are expected and encouraged to compare  their  projections with
 those of the areawide planning organization and/or county
 planning agency,  it is explicitly stated in the State regu-
 lations that, grant assistance is  based  on the population
 projected by the appropriate DOF  series.   Past trends in
 population  growth  are valuable but are  not consistent to
 the point that they would be used to forecast future trends,
 especially  in the  Tahoe Area where highly dynamic seasonal
 changes are evident.

      The local land use planning  policies and  procedures do
 not set forth growth  policies per  se.   Rather,  the plans
 delineate the spatial dimensions  of land  use  at some future
 (unspecified)  date.   The  land use  plans do not provide  for
 rate  and time of build-out and, therefore,  it  is  difficult,
 if  not  impossible, to derive a population in  1984 from  land
 use maps which can be used reliably for sewer  sizing.   In
 addition, the highly  dynamic nature of  Tahoe-Truckee Area
 population  and the components of population are related  more
 to  the  seasonal recreation pattern rather than  any land  use
 pattern.

      Since  the sewer  system sizing  for  this project  was  not
 based upon  an  analysis  of  wastewater generation from existing
 and projected  land uses but  upon statistical demographic
 trends,  the  latter approach  to  sewer sizing does  not depend
 on what  existing land uses  are, or  what future  land  uses  will
 be, with or without the sewerage project.  The  sewerage works
will  serve wastewater flows derived from  existing  land uses
 (and, therefore,  existing peak  seasonal population),  and will
 serve whatever new wastewaters are  derived from any  new land
uses up  to the capacity limitations imposed by  the demographi-
cally based design size.

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                               -4-
     There  is sufficient reserve capacity  in  the  eligible
treatment plant and interceptor to accommodate  the  design
year population derived for each local sanitary district:
                      Flow Comparison MGD
    District
 August 1973
 Summer Peak
Existing Flow
  Summer Peak
Grant Eligible

TCPUD/NTPUD
ASCWD
SVCWD
TSD
Truckee
Canyon
AVG
1.52
0.04
0.09
0.32
- 0 -
MAX
2.00
0.05
0.11
0.95
- 0 -
Treatment
(1985)
2.94
0.16
0.32
1.16
0.25
Interceptor
(1994)
3.89
0.22
0.44
1.35
0.33
Total Treatment
Plant Design Capacity
                     4.83
     This analysis  shows  that grant eligible capacities as
derived by the population projection methodologies specified
by the California Clean Water Grant Program Regulations  (4)
provide sufficient  reserve capacity in the T-TSA system as
required by Section 204(a)(5)  of the Federal Water Pollution
Control Act  (FWPCA).

     fa.   It u)ou.Łd  at&o be. appropriate, to e.x.pŁain the. ie.la.tion
     OjJ th
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                                -5-


R-lb.   The Lake Tahoe Basin was designated by the States of
California and Nevada, as an interstate planning area on
March  11 ,  1974.  The TRPA was  designated as its single repre-
sentative  organization.  The EPA,  on August 5, 1974, approved
the designations, and on December  23,  1974 a grant offer in
the amount of $650,000 was made to TRPA.

     The 208 work plan is devoted  to the development of an
"Erosion Control and Surface Water Management Plan" for the
Lake Tahoe Basin.  All areas outside the Basin are excluded.
The T-TSA  service area lying outside TRPA's jurisdiction
(Zone  2  of the EIS)  has been made  a non-designated area by
the State  of California.  Therefore,  the SWRCB is doing waste
treatment  management planning  for  point and non-point source
control  for the T-TSA service  area outside of the Tahoe
Basin  pursuant to Section 303e of  the  FWPCA.

     The 208 Plan is devoted almost entirely to the non-point
source pollution of  Lake Tahoe.  Sewerage facilities will be
considered to the extent that  future  sewerage needs are pro-
vided  in the existing export systems.   For purposes of the
Tahoe  208  Program,  the T-TSA export system,  located in the
jurisdiction of TRPA, is assumed to be existing or "in place".
No new construction  is anticipated and the program will have
no direct  or immediate bearing on  the  present grant offer to
T-TSA.

     The TRPA is required by Section 208 to plan a waste
treatment  management program for pollutants  eminating from
point  sources over a twenty-year period.   Therefore,  planning
for future facilities within the common  TRPA/T-TSA jurisdiction
will be  developed through the 208  planning process.

2.   Se.ct4.on 114 oj  the. FWPCA kmo.ndmo.ntA  (P.I.  92-500]
          Spe,c.
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                               -6-
                        ?m>ithe
      beŁ*.eve EPA ha&  not ye,t ade.qu.ate.ly addie,64ed the.
      OjJ ŁfU* p>iOje.Q.t  on the. e.^e.c.tive. imple.me.ntation o<(
      Season 114.

R-2.   In Section 114  of the Federal Water Pollution Control
Act Amendments of 1972, Congress expressed a concern for the
"fragile ecology of Lake Tahoe" and directed EPA to prepare
a major study of the  Lake Tahoe Basin to accomplish the
following  objectives:

      1.    Conduct a thorough and complete study on the
           adequacy of  and need for extending Federal over-
           sight  and control in order to preserve the fragile
           ecology of Lake Tahoe.

      2.    Examine the  interrelationships and responsibilities
           of the various agencies of the Federal Government
           and State and local governments.

      3.    Consider the effect of various actions (of Federal,
           State,  and local governments)  in terms of their
           environmental impact on the Tahoe Basin,  treated
           as an  ecosystem.

      4.    Establish the necessity of redefinition of legal
           and other arrangements between the various govern-
           ments .

      5.    Make specific legislative recommendations to
           Congress .

      The Lake Tahoe Study (6)  is now in its final form and
will  be transmitted to Congress in the near future.   The
study has  undergone an extensive review by  State and Federal
agencies and by  the Executive Office of the President.

      The study examines the  environmental and ecological
dynamics of  the  Lake Tahoe Basin;  the myriad activities of
Federal agencies,  State agencies,  the TRPA,  local general
purpose governments, special purpose districts,  and pri-
vate  parties;  and  the  legal  and institutional arrangements
in operation  in  the Tahoe Basin.   The study identifies
problem areas  as legal  or institutional  deficiencies which

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                               -7-
are preventing  fully effective management of environmental
and ecological  values, and which consequently are  impacting
on the  "fragile ecology of Lake Tahoe".  The study examines
tools and options to remedy the problems; the options range
from Federal policy statements and coordination, to  legal
changes in the  Tahoe Regional Planning Compact/ to air and
water pollution control programs, to land acquisition.
Finally, the study makes specific recommendations  to Congress.

     The Lake Tahoe Study does address land use issues and
sewerage issues in the Tahoe Basin.  The historical  example
of exemplary intergovernmental coordination to implement the
sewer export mandate to protect the quality of Lake  Tahoe is
given; moreover, it is directly acknowledged that  the sewer-
age export systems constructed with State and Federal funds
were oversized  and contributed to the stimulation  of urban
development.  This knowledge of the sewer/land use relation-
ship prompte'd EPA to rigorously review population  forecasts
for the T-TSA Regional System.

     The Lake Tahoe Study recognizes that even as development
proceeds in the Tahoe Basin within the confines of the Tahoe
Regional Plan and ordinances and within the available sewerage
capacity, land  and water quality impacts will occur  as land
and soils are disturbed.  Erosion, sedimentation, and the
transport of nutrients into Lake Tahoe are very critical
environmental and ecological problems, and are directly
related to the  intensity of land use in the watershed.  At
the same time that EPA and the States are pursuing a strategy
to protect water quality through sewage export, an active
program of erosion control and surface water management is
in progress to remedy the impacts of urban development that
has been and is permitted in the watershed.   For example,
EPA has awarded a major $650,000 grant to TRPA to carry out
an areawide waste treatment management planning program
pursuant to Section 208, FWPCA.   This program will result in
the development and implementation of erosion control and
surface water management plans to correct existing problems
and prevent new occurrences.

     EPA believes that our decisions on the  sizing and
environmental impact of the T-TSA project and the implemen-
tation of Section 208 in the Tahoe Basin are actions that
are,  in fact, consistent with the Lake Tahoe Study's analysis
and recommendations.

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                                -8-


3.   E^ect ot that it  be
     fie.c.OYi&ide.fie.d.  land  tie.atme.nt &oi at  lua^t a poition  0(J
     the. &hktu.e.nt (u)hic.h  w»oaŁd piovide. ^u.ithe.1 pacification
     via natiie.nt aptake.  by v eg e.tatio n , and ie.tain OjJ wate.1
     to the, n.ive.1 via ande.idiain&] woatd appear, to me.iit
     fiuithe.1 anaty&i&.

           Cto&e. c.on^ide.iation ofi thi& Land tie.atme.nt atte.ina-
     tive.  vooaid be. c.on*>it>te.nt u)ith Se,ction 20? o& Title.  II Oj}
     the. fe.de.iat Wate.1 Poltation Contiot kc.t kme.ndme.nt&  o/J
     1972. U

R-3a.  Although there will be certain total dissolved solids,
chlorides, etc., remaining in the effluent from the regional
treatment  plant as suggested by CEQ, it has been shown in
Table  13-3 of the Amended Project Report  (1) and the Table
which  appears on page 236 of the Environmental Impact State-
ment  (5) that, with the high degree of treatment proposed,
the water  quality standards established for the Truckee  River
will not be violated under the proposed treatment and disposal
conditions.  However, as  a result of the calculations made in
these  studies it was apparent that an extremely high level of
treatment  operating at a  high level of reliability would be
required in order not to  violate the Truckee River standards .
\J FWPCA  Amendment ie.qaiie. that "wa&te.  tie.atme.nt manage.me.nt
ptanA and piac.tic.e.6 bkatZ. piovide. &oi the. be.&t piac.tic.abte,
voa&te. tie.atme.nt te,c.hnotogy betfote any di&c.haige. into ie.c.e.iving
viatui,  inclading ie,c.taiming and ie.cycting 0(J wate.1, and  c.on-
&ine.d di&po&at oft pollatant* &o the.y witt not migiate.  to caa4e
taate.1 01  othe.1 e.nviionme.ntal pottation  . . .  and the. ie.c.yc.ting
0)5 pote.ntial & engage potlatantA thioagh the. piodac.tion  o
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                              -9-
     Land treatment was considered during these studies, but
it was concluded that this method of treatment could not
achieve the necessary results in terms of nutrient removal
and thus could not meet the stringent standards set for the
Truckee River.  Although nutrient uptake occurs in a land
treatment system, essentially complete nutrient removal as
dictated by the receiving water standards could not have
been possible.

     Additionally, the practice of land treatment by irriga-
tion is impractical in this cold, wet, wintry climate, in
these soils, and in this terrain.  A very short growing
season in this sub-Alpine environment results in sparse
growth in the vicinity of the plant site.  It is not consid-
ered feasible to rely on nutrient removal by plant uptake
in this location.  Another problem exists in the vicinity
of the airport, less than a mile from the proposed site.
Fog generation and consequent airport closure is a common
occurrence due to nearby ponds and surface moisture available
for the fog generation.  The peculiar climatic conditions that
cause this fog have prompted the airport district to discourage
additional reservoirs or surface spraying of any kind during
critical periods and in fact the airport board is anxious to
eliminate the lagoons that are part of the present disposal
system of the Truckee Sanitary District.

     In addition to the studies which have indicated that
the receiving water quality standards will not be violated
under anticipated advanced waste treatment conditions, it
should be noted that pilot studies and stream simulation
studies were conducted by an engineering consultant (7) and
by the University of California's Sanitary Engineering
Research Laboratory. (8)  The consultants operated a pilot
advanced waste treatment plant; the University study team
conducted the stream simulation analyses.  The results of
these studies indicated that the pilot plant effluent did
not increase the algal growth potential in the Truckee River
but that lesser levels of treatment had significant detri-
mental effects.  Laboratory spiking tests corroborated the
field studies.

     The Regional Water Quality Control Board has,  in its
Board Order 6-74, (9)  required compliance "with the Monitoring
and Reporting Program No. 74-44 and the 'General Provisions
for Monitoring and Reporting1  as specified by the Executive

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                              -10-
Officer." By these provisions  the Regional Board will be
able to keep close control  of  the effluent discharges and to
assure protection of the  receiving aquifers as well as the
Truckee River.

     fa.   Ene.n.gy Con4eivaŁtow  A4pec.t6

          Land tfie.atme.nt  o& e.&&tue.nt, a& dji&c.u.t>*e.d above., would
     aŁio appeal to be.  a  te.&&  e.ne.iQy Jinte.n&po&aZ. me.thod.   The. e.ne.fi.gy consumption
     que,&tia.
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                               -11-
requirement.   The carbon dioxide produced from this process
and the burning  of the methane gas will be used for the
recarbonation  processes following lime treatment.  The
stabilized organic solids from this treatment process will
also be returned to agricultural lands if a market can be
found.

     The proposed treatment plant processes are described in
considerable detail in a Preliminary Design Report (10)
dated February 1974.   This study also included a number of
analyses of energy consumption for various unit processes.
Comparisons were made of energy consumption for the following
processes:  Oxygen vs.  air for biological treatment; ozone
vs. chlorine for disinfection; chemical vs. electrolytic
processes for  the ammonia stripping-recovery process; and
incineration vs.  land disposal for both organic and chemical
sludge.  These energy considerations and the rationale
leading to selection of the processes providing for the most
optimum energy budget are contained in Chapter II of the
report.  On-site sludge incineration and calcining were
eliminated from  the proposed plant as a result of these
energy analyses.

4.   E^e.c.t on Qu.ant4.ty o& Wa.te.si. Jin Pyramid Lake.

          Ex.plic.it information on. the, e.^e.c.t afi the. tie.at-
     me.nt me.thod on the. &u.H.vivat OjJ Pyramid Lake. i& a matte.*.
     0(J Qfie.at  importance, to the. Paiate. Indian Ttiibe..   EPA
     Ah.ou.ld clarify why it be.iie.ve.& that (aate.fi volume. M4.it
     be ^,u.^ic.ie.ntiy  high to &ati&{>y the. Indian*' wate.1
     Jie.qu.itie.me.ntA  Jin  the. Z.OUMLH Ttiu.c.kee R-C.VC.A and in Pyramid
     Lake..

R-4.  The proposed alternative is deliberately chosen and
designed to retain all  effluent within the Truckee River
system indirectly through underground aquifers near the
proposed plant site.   There will be no appreciable water
loss to the Truckee system as a result of the water use,
sewage treatment,  and disposal conditions.  The water con-
sumption and indirect recycle through injection of effluent
into the aquifer  only amounts to a few percent of the normal
flow in the Truckee River.

     Water quality effects in Pyramid Lake will be insignifi-
cant since effluent quality has.been dictated by the water
quality standards  of  the Trucked River receiving water near
the plant site.   Increases in such parameters as nutrients,

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                               -12-


total dissolved solids, chlorides,  etc.,  which may result
from the  plant effluent are negligible  in comparison to
current background levels existing  at Pyramid Lake.  If
there is  any significance in the quality  differences at
Pyramid Lake as a result of the proposed  treatment facility,
it is that  the current nutrient emissions from the existing
sewerage  agencies will be greatly reduced as a result of the
proposed  high degree of treatment.

     Chapter V of the Amended Project Report (1)  deals
exclusively and specifically with the water  environment and
the subject of water quantity in the Truckee River systems.
Estimates of the natural flow of the Truckee River were
presented on page 72 of that report and indicate  a mean flow
into Pyramid Lake of 549,000 acre-ft. per year.   This is
referred  to on page 128 of the EIS  (5) where it was stated
that the  consumptive loss due to the T-TSA project would be
less than 1800 acre-ft.  In view of the insignificance of
this consumption loss and of the bi-State water compact
allocation  of water to California from the Tahoe  Basin of
23,000 acre-ft.,  the reduction in flow in the Truckee River
is not in any way critical.   The availability of  water in
the Tahoe-Truckee Basins may be a significant influence in
the future  with regard to decisions on the extent of allow-
able or desirable population growth in the area but this
project,  however,  is well within the bounds  of water avail-
ability to  California.

5.   The,  future, o&  the. Eating  Tahoe. City Piimaiy TfLe.atme.nt
     Plant	

          It  4.&  unc.le.ai fiiom the. intimation  pie.& nnte.d whe.the.1
     the.  Tahoe.  City tie.atmc.nt plant which  wa-6 upgraded in 7969
     i&  to  be.  pha&e,d out.   We. unde.i&tand  that thi& plant i*
     pie.*cntly  ove.iloade,d;  hou)e.ve.i,  lathzi than abandon it, a&
     i*  &u.gge.&te.d -in the, EIS,  it&  poA&ible. ute. Ł01 tzcondaiy
     tne.atme.nt  a& pait oft  the. fie.Q4.onal *yAte.m mtght allow a
     >ie.du.c.tik.&.  M.te.H.nat4.ve.ly,  -cjj  the. old plant    to be.
     he.ld i.n me.i\)e. ^on addtt-ional jju-tu'ie tne.atme.nt capacity,
     th
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                              -13-
R-5.  The Amended Project Report  (1) referenced in the EIS  (5)
makes it clear that the intent is to abandon the Tahoe City
primary treatment plant.  There is physically no room at the
existing site for plant upgrading to secondary treatment so
it will not be maintained in reserve.  The U.S. Forest Service
cinder cone is to be returned to its native state when the
permit expires and the land used in this system should be
returned to other beneficial use.  Equipment in this plant
is not compatible with the proposed new facility.  The facil-
ities in the existing Tahoe City plant are also needed for
treatment up until the time the sewage is diverted to the
new T-TSA facility.

     In the Addendum to the Amended Project Report (11)
published in May 1973, three specific plans were presented
that would retain the Tahoe City treatment site.  Table 4 on
page 34 of that report clearly demonstrates that even after
full tertiary treatment including nutrient removal effluent
from the cinder cone would violate the present Truckee River
standards at the 100 cfs flow rate.  The volume of water is
regulated at the Tahoe Dam by the Federal water-master to
maintain a proper balance in the Truckee River drainage.  For
example, if the Truckee River system were operated in accord-
ance with the Bureau of Reclamation Operation Study S-l (see
pages 86-89 of the Amended Project Report (1)), the monthly
average flow in the river at the point of discharge from the
cinder cone would be below 100 cfs in an average of seven
months each year.  At that flow, the standards for total dis-
solved solids, chlorides, nitrogen and phosphorus would be
exceeded.  Additionally, direct discharge to the surface
waters of the Truckee River from any treatment plant is pro-
hibited in the Federal/State Water Quality Standards.

     The Tahoe City Public Utility District is not presently
overloaded although the rate of connections to this system
must be allocated very carefully to keep within the terms
of the U.S. Forest Service special use permit and those of
the Lahontan Board.

     The new sewage treatment plant and interceptor are not
oversized for population to be served due to the retention
of the Tahoe City Treatment Plant. The regional system was
sized for the population projected for the entire service
area.

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                               -14-
6.    In^iltiation and E^^iltiation

           It  ha&  been Augge-a-ted by at te.at>t  one  ie.vie.tae.1 that
      EPA  condition it* giant on a ie.quiie.me.nt  tfoi..i -6ugge-6ttnta>c.n4
      that exjj/c^^a^on can be de-tec-ted through wate.fi quality
      monitoring and enforcement otidtn& a4 needed.
                    to u.4 moie co4t-e^ect^i;e,  and
          Section  201 [g] (3)  OfJ tne FWPCA Amendment,  faon tke.
     kdmini&tnaton. to nnquitie. the. apptic.ant pnion  to  giant
     approval,  to  &hou) that each Aei/oe/i coŁŁect-con  &ij&tz.m that
     wiLt di&c.han.ge. into the. proposed tie.atme.nt  u)on.k& ,  whe.the.fi.
     aid on  n-ew, i& not ^abject to exce^-tve infatuation.
     Th-e Aize.  oft the. &y&te.m buitt might be. abte.  to be adju&tzd
     dovonwatid  i& Auch in^ittiation 0(J wate^t couŁd  be  /tedaced.
     In addition,  mainte.nanc.e. oft wate.fi quality wiif. be be.tte.n.
     a44a/ted by &uc.h a ie.quiie.me.nt.

R-6.  An infiltration/inflow analysis was included in the
February 1974  Preliminary Design Report (10) as  Chapter 4.
A cost effective analysis in that report, in accordance with
State and EPA  guidelines,  indicated that the local agencies
were making  progress in controlling infiltration and  that such
infiltration-control programs were continuing.   The I & I
analysis concluded that infiltration/inflow to the new
regional treatment facility has been shown not to  be  exces-
sive.  However, many segments of the collection  systems which
exist in some  of the districts have severe infiltration/
inflow problems.   The most cost effective solution to accom-
modate these isolated elements of infiltration/inflow entering
the sanitary sewer system is based on rehabilitation.  An
example of this is the older portion (1908) of the Truckee
collection system.   This portion of the Truckee  system is now
being replaced and work is continuing in all districts  on
these isolated segments of existing collector  lines subject
to infiltration/inflow.

     Since raw sewage is being pumped in close proximity to
Lake Tahoe,  the real possibility of exfiltration through
leakage or breakage in the lines exists.  Raw  sewage  entering
Lake Tahoe could have a severe impact on water quality  if it

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                              -15-
were allowed to occur over a  long period  of  time.   The moni-
toring programs in Lake Tahoe, while  not  as  comprehensive as
may ultimately be desirable,  are capable  of  detecting gross
pollution of the near-shore waters.

7.   HydfLoge.otog.oŁ.og4.c.
R-7.  Hydrogeologic  studies  (12)  have been completed and were
received in the EPA  regional  office  in January 1975 (T-TSA
transmittal letter dated  15 January  1975) .  These studies
concluded the following:

     1.   The 22-acre disposal  site  will readily accept
          design percolation  flows.

     2.   The height of the mounded  percolate will not rise
          high enough to  impede the  downward movement of
          percolating effluent.

     3.   The mounded percolate will not reach the existing
          invert of  the deepest gravel pit within Sanderson's
          property.

     4.   Movement of the percolated effluent, upon reaching
          the water  table, will be northeasterly where it
          will surface in the Truckee River and Martis Creek.
          The flow will be away from any existing domestic
          supplies to the south drawing water from the same
          aquifer system  or  systems  in hydrologic continuity.
          Any percolated  effluent which did penetrate into
          the Truckee Formation, which is unlikely to occur,
          would also eventually surface into the Truckee
          River or Martis Creek.

     5.   The total  time  for  the effluent to reach the points
          of discharge into  the Truckee River or Martis Creek
          will vary  from  140  to 280  days depending on the
          discharge  rate  and  flow path.

     6.   Since the  water quality of the plant effluent will
          be extremely good  in terms of suspended and organic
          matter, no appreciable variations from the model
          predictions are expected with prolonged disposal.

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                         BIBLIOGRAPHY


 1.    Dewante &  Stowell;  Cook Associates,
           Amended Project Report,  Regional  Sewerage  Project,
           Tahoe-Truckee  Sanitation Agency,  Sacramento,
           February 1973.

 2.    Jones & Stokes Associates,  Inc.,
           Draft Environmental Impact Assessment,  Tahoe-
           Truckee Sanitation Agency, Sacramento,  February  15,
           1973.	

 3.    State Water Resources Control Board; Lahontan Regional
       Water Quality Control Board,
           Water  Quality Control  Plan Report, North Lahontan
           Basin  (6A)."Draft,  South Lake Tahoe, February 1975

 4.    State WaŁer Resources Control Board,
           Clean  Water Grant  Program Regulations,  Sacramento,
           August 16, 1973.             	

 5.    U.S.  Environmental Protection Agency; Region IX,
           Final  Environmental  Impact Statement; Wastewater
           Treatment and Conveyance  System, North Lake Tahoe-
           Truckee River Basin  (Tahoe-Truckee Sanitation
          Agency), San Francisco,  September 17, 1974.

 6.    	
          The Lake Tahoe Study; .. .as requested by_ the 92nd
          Congress in Section 114 oT the FedeFaiWater Pollu-
          tion Control Act Amendments of 1972, San Francisco,
          May 1974.

7.   Environmental Quality Engineering, Inc.,
          Demonstration of a Biological-Chemical-Physical
          Treatment Process for Assessment of  Biological
          Effects on the Truckee River.Preliminary Report,
          Oakland, December 1972.

8.   State Water Resources Control  Board,
          Assessment of Biological  Effects of  Treated Waste-
          water  on the Truckee RiverTFTnar~Report by
          H. P.  Skarheim,  et al., Publication  No.  52,
          University of California, Sanitary Engineering
          Research Laboratory.  SERL Report  No.  73-2,
          Berkeley, June  15,  1973.

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9.   California Regional Water Quality Control Board,
       Lahontan Region,
          Board Order No. 6-74; Waste Discharge Requirements
          for Tahoe-Truckee Sanitation Agency..., South Lake
          Tahoe, April 25, 1974":

10.  Cornell, Rowland, Hayes & Merryfield; Clair A. Hill
       & Associates,
          Preliminary Design Report; Truckee Interceptor,
          water Reclamation Plant, Effluent Disposal System
          - Regional Water Reclamation Project, Tahoe-Truckee
          Sanitation Agency, Redding, Feburarv 1974.

11.  Dewante & Stowell; Cook Associates,
          Addendum, Amended Project Report, Regional Sewerage
          Project,  Tahoe-Truckee Sanitation Agency, Sacramento,
          May 1973.                           	

12.  Cornell,' Rowland, Hayes & Merryfield; Clair A. Hill
      '& Associates,
          Hydrogeological Investigation of Land Disposal of
          Reclaimed Wastewater Near TrucEee7~California for
          Tahoe-Truckee Sanitation Agency, Redding, November 1,
          1974.
          All of the above references,  with the exception of
          #7, are available for viewing at the U.S.  Environ-
          mental Protection Agency,  Region IX,  100 California
          Street, San Francisco,  California.

          Number 7 is available for  viewing at the State  Water
          Resources Building, Division  of  Planning and  Research,
          Room 1018-25-K,  1416  Ninth Street,  Sacramento,
          California.

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