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BACKGROUND

   Incline Village, Nevada, uses a
   constructed wetland for disposal
   of secondary effluent. Starting with
an existing, mineralized, warm-water
wetland near Minden, Nevada, the
Incline Village General Improvement
District developed a system which uses
natural processes both to renovate
wastewater and benefit wildlife. With
this system, Incline Village can meet
several goals to protect the environment:

•  dispose of treated effluent effectively
   and economically
*  expand the existing wetland habitat
   for wildlife
•  provide an educational experience
   for visitors
   Until 1975, effluent treated at the
Incline Village General Improvement
District's 3.0-mgd activated sludge plant
was exported from the Lake Tahoe
Basin and discharged into the Carson
River during the winter and used for irri-
gation of hay fields during the summer.
   A discharge permit issued in 1975
required either more stringent treat-
ment standards or a year-round, land-
based disposal system. In 1979, a facility
plan funded by the U.S. Environmental
Protection Agency (EPA) and prepared
by CH2M HILL recommended meeting
a zero surface discharge standard by
using land application during the grow-
ing season and constructed wetland
enhancement during the remainder of
the year. Local agency reviews and
public hearings were held, and the
wetland concept was finally approved
in 1982. The project was designed by
the environmental engineering firm,
Gulp »Wesner «Culp, with technical
assistance from Dr. Robert Kadlec of the
Wetlands Research Group. The design
was completed in 1983 and construction
was finished in November 1984.
The Incline Village Wetlands
Enhancement Facility is
located south of Carson City,
Nevada, about 10 miles east
of Lake Tahoe.
                           ^Village
                              Wetlands

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 SITE DESCRIPTION
       20-mile pipeline carries the
       treated effluent from the treat-
           t plant to the Wetlands
 Enhancement Facility. Constructed
 wetland cells, berms, a flood dike, and a
 distribution ditch are the main compo-
 nents of the system. The 770-acre site
 is made up of several distinct areas:

 •  constructed wetlands

 •  natural warm-water wetlands

 •  seasonal storage/waterfowl areas

 •  effluent storage area

 •  upland area

   Eight constructed wetland cells are
 the primary disposal
 area for the treated
 effluent. There is no
 surface discharge from
 the wetland disposal
 area because of
 evaporative water
 losses. Each cell has a
 deep channel down its
 center that discourages
 growth of emergent
 vegetation and
 furnishes a landing
 area for waterfowl.
 Islands within this
 channel serve as
 nesting sites.
  The natural warm-
water wetland provides
 a natural habitat for
plants and animals and
is not part of the
disposal process.
  The seasonal storage/waterfowl
areas store excess water during periods
of low evaporation and high rainfall.
They are dry during summer and fall,
except for a small ponded area fed by
warm-water springs. Three islands in
this area provide nesting habitat for
waterfowl. Each of the islands was
planted to provide food, screened
areas, and trees for birds.
  The 2.8-million-gallon effluent
storage area is used only during high
flows or heavy rainfall. The 200-acre
upland area is used to dispose of
effluent by spray irrigation during
extended rainy weather.
A resident population of
Canada geese use the berms
and islands for nesting.

Wetland treatment cells with
islands were constructed
around the existing warm-
water wetlands.

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OPERATIONS AND  MANAGEMENT
      The treated effluent passes through
      the 390-acre system of wetland
      cells and is disposed of through
evaporation, transpiration (evaporation
through plants), and percolation (seep-
age through soil). The system works in
harmony with the existing warm-water
wetlands, adapts well to year-round fluc-
tuations in weather and temperature,
and meets state and EPA water-quality
requirements while avoiding surface
discharge to the Carson River.
   Effluent flows from Cell 1 through
Cells 2,3, and 4 before overflowing to
the distribution ditch. Overflows from
Cells 3 and 4 are diverted to Cell 5 for
storage and evaporation. Water that
must be stored is held in Cells 6,7, and 8.
   Using weather instrumentation and
monitoring equipment, plant operators
determine rainfall, evapotranspiration
and percolation rates, and groundwater
quality. These data are used to estimate
the evaporation rates at the site and to
          Site Boundary
      determine compliance with groundwater
      quality standards.
        The size of the constructed wetland
      needed for evapotranspiration and
      percolation of effluent was determined
      by calculating several water balances
      for the site. Evaporation rates were
      estimated with the Penman method
      and were based on limited data available
      for the area. Subtracting the evapo-
      transpiration and percolation from the
      rainfall yielded the net water loss from
      the site. Dividing the net water loss into
      the effluent volume gave an estimate
      of the required acreage.
         Percolation is critical to successful
      operation of the project. At least
      1.1 inches of percolation per month
      is required at the projected flow rate.
      If percolation occurs at this rate, only
      175 acres are needed to treat the efflu-
      ent. If percolation does not occur, as
      much as 450 acres would be required.
                                                                    The Incline Village Wetlands
                                                                    Enhancement Facility includes
                                                                    a total of 770 acres of wetlands
                                                                    and uplands.
                                                                        Operations, Building
                                                      Saratoga
                                                      Hot Springs
                                                                Effluent
                                                              Pipeline
               Irrigation Pipe

           Access Road
Seasonal Storage
Waterfowl Area
                                                                            Natural Warm
                                                                            Water
                                                                               ands
                                                                                   Observation Trail
                                                                                Weather
                                                                                Station
                                                                                       Site
Distribution,
 Ditch'	L  Cell 4;
                                             14" Effluent
                                             Pipeline _J  Warm Water
                                             Extension  1  Outlet Sewer
                                                                                        14" Effluent
                                                                                       / Pipeline

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 PERFORMANCE
                                         3000 -/
      | ecause there is zero discharge
          surface waters from the
      "incline Village Wetlands
 Enhancement Facility, no surface water
 quality criteria must be met. However,
 many parameters of regulatory interest
 are monitored in the wetland cells.
 Even though all surface water evapo-
 rates or is lost to percolation, water.
 quality improvements can be observed
 as the water passes through the cells
 in a serial pattern.
   For seven years, nitrogen and phos-
 phorus levels have been reduced in the
 water, even during the winter. Nutrients
 in the last cells display only 2 to 3
 percent of the concentration values in
 the incoming wastewater effluent.
   The effect of evaporation can be seen
 in the increases of total  dissolved solids
 (TDS) and chloride ion as water moves
 through the cells. The evaporites in the
 original desert soils are rearranged by
 water movement, with increases in
 concentrations in the downstream cells.
 However, there is no evidence of a
 continuing buildup of these ions in
 the downstream cells. Apparently,
transport  of solutes from upstream
to downstream cells has reached a
balance with other processes.
        CelM
               Cell 2
                       Cell 3
Cell 4    Cell 5*  ~Cef| 6 '  Cell 7 '  Cell 8
                                              * Average of Cells 5A and SB
 The concentration effect of evaporation can be seen in the increase of total
 dissolved solids as water moves through the cells.
    5-f
       CelM
              Cell 2
                      CelI3
                             Cell 4
                                     Cells*   Cell6    Cell 7    Cells
                                              * Average of Cells 5A and 5B
The concentration of ammonium nitrogen is reduced as the water flows
through the cells.
         Wetlands Design Criteria

  Flow, Average Annual	1.66 mgd
  Flow, Maximum Daily	.2.68 mgd
  Influent Quality
    Suspended Solids	20 mg/l
    BODs	i,	20 mg/l
    TDS	;.....	240 mg/l
    Total Phosphorus as P	6.5 mg/l
    Total Nitrogen as N	25 mg/l
  Constructed Wetland Area
    Cell 1	„,;	...37.9 acres
    Cell 2	..4.........V..	.........33.2 acres
    Cell 3	;.	27.3 acres
    Cell 4	;	23.4 acres
    Cell 5 (overflow area)	117.3 acres
    Cells 6 & 7 (floodp'lain area)	105.6 acres
    Cell 8 (seasonal storage)	42.5 acres
 Wetland Depth
    Emergent Marsh .....	0.5 feet
    Open Water	2.0-3.0 feet

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ANCIILARY BENEFITS
Plant Communities
Wildlife Habitat
      Vegetation is essential to the
      success of the wetland. Plants
      increase evapotranspiration by
as much as 20 percent in the summer
and improve water quality. Wetland
vegetation includes rush meadow, three-
square bulrush, tule cattail, and willow
thickets. Upland vegetation consists
primarily of sagebrush, rabbitbrush,
greasewood, and salt grass, which
tolerate the alkaline soils. Floodplain
vegetation includes rabbitbrush and salt
grass, plants which can exist in saline,
silly loam, and clay soils.
   Project implementation has allowed
existing plant species to flourish.
Careful planting of hundreds of trees
and bushes added a new component to
the ecosystem, with taller vegetation
providing new perching and nesting
areas for hawks and eagles.
      The wetlands provide three types
      of wildlife habitat: permanent
      wetlands, seasonal wetlands,
and uplands.
   Many types of aquatic and nonaquatic
wildlife coexist at the site. Aquatic
invertebrates such as insects, worms,
snails, and crayfish eat algae and other
plants and serve as food for larger
organisms. Fish such as largemouth bass,
black bullhead, green sunfish, mosquito
fish, and carp were identified before
construction and were transferred to
several areas within the site.
   Birds occupying the site include
ducks and geese, shore birds, raptors
(hawks and eagles), and passerine
(such as blackbirds). Many migratory
species travel through the Carson
Valley and nest on the islands in the
seasonal storage/waterfowl area or
the grassy areas along the edges of the
cells. Animals common to the area
include deer, coyote, skunk, mink,
muskrat, rabbit, squirrel, chipmunk,
 and the western yellow-bellied racer.
The natural warm-water
wetlands provide a year-round
habitat when the constructed
wetland cells are dry.
                                        The yellow-headed blackbird
                                        prefers nesting in the emergent
                                        marsh areas.

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Recreational Uses
       n observation area is provided
       at the operations building in the
          theast corner of the site to
encourage the public to enjoy and learn
about man's use of his natural environ-
ment. Observation trails traverse the
warm-water wetlands and created
wetlands so that visitors may experience
the diverse wildlife and vegetation at the
site and see how the project operates.
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Migratory trumpeter swans find winter habitat at the wetlands enhancement facility.

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ACKNOWLEDGEMENTS
Incline Village General Improvement District
Elected Trustees

Robert Wolf, Chairman
Pamela T. Wright, Vice-Chairman
Roberta Gang, Secretary
Jane Maxfield, Trustee
Greg McKay, Trustee

Professional Staff
Robert A. Hunt,  General Manager

John R Shefchik, District Engineer

Don N. Richey,
   Sr., Operations Superintendent

Grant Funding
U.S. Environmental Protection Agency,
   Region 9
Nevada Division of
   Environmental Protection,
   Construction Grant Section
            Design Team

            CH2M HILL
               Facilities Plan and Conceptual Design

            Robert Chapman, Project Engineer

            Richard Mishaga,
               Environmental Scientist

            Gulp »Wesner«Culp, Design

            Wetlands Ecosystem Research Group,
            Wetlands Consultation

            Robert Kadlec, Senior Consultant

            This brochure was prepared by
               CH2M HILL for the
               U.S. Environmental Protection Agency.
           Project Cost
   Description
Amount
   Engineering/Inspection... $ 623,493
   Land	$772,503
   Construction	$ 3,568,000
   Total Project 	$4,963,996

   Innovative/Alternative grants funded
   85 percent of the project.

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