Ellen Brook

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					                                                                           Ellen Brook


E  llen Brook is a natural, ephemeral waterway and has the
   largest catchment area of all sub-catchments on the Swan
Coastal Plain. It discharges into the upper Swan River near
                                                                                                   Groundwater flows towards Ellen Brook from the Gnangara
                                                                                                   groundwater mound in the west and from aquifers on the
                                                                                                   Dandaragan Plateau to the east. Natural springs are present in
West Swan Road in Belhus.                                                                          some areas.
Much of the Ellen Brook Catchment has been cleared for                                             The Swan River Trust monitors a site for flow and nutrient
agriculture. Some of the remaining areas of vegetation have a                                      concentrations at the lower end of the brook, near Great
high conservation value, containing rare and endangered flora                                      Northern Highway. This site is useful to estimate what is leaving
and fauna.                                                                                         the catchment, but does not accurately represent nutrient
                                                                                                   concentrations in upstream tributaries. An
Soils in the Ellen Brook Catchment are comprised mainly of
                                                                                                   autosampler has been installed at
Bassendean sands in the west, Guildford clays along Ellen
                                                                                                   this site to precisely measure how
Brook Valley and red earth soils to the east. Shallow lenses
                                                                                                   nutrient concentrations vary
of sandy-clay and loamy-clay duplexes are also common in
                                                                                                   during storm flows.
valley areas giving rise to perched wetlands during wet periods.


Facts and figures
Length                       ~ 65 km
Average rainfall             ~ 800 mm per year
Gauging station in proximity Site number S616189
to monitored site
Catchment area                           715 km2 (total)
                                         664 km2 (monitored)
River flow                               Ephemeral (May to December)
                                         No major water supply dams in catchment
Average annual flow                      ~ 18.9 GL per year
                                                                                                                                                           Muchea
Percentage of average                    ~ 7.3% of total inflow per year
inflow to Swan River
Main land uses                           Broad scale pasture, horticulture, viticulture,
                                         townships, poultry and military establishments                               Legend
                                                                                                                          Monitored site
                                                                                                                          Town
                                                                                                                          Major road                                         Bullsbrook
                                                                                                                          Stream / River
                                                                                                                          Industrial / Commercial
                                                                                                                          / Roads
                                                                                                                          Future urban
                                                                                                                          Agriculture
                                                                                                                          State forest
                                                                                                                          Bushland
                                                                                                                          Suburban
                                                                                                                          Water
                                                                                                                                                                Monitored Site

                               Photo: Dieter Tracey                                     Photo: Dieter Tracey                          N
                                                                                                                           2    0    2      4   6 kilometres
The confluence of Ellen Brook (top) with the             The dark, tannin-stained water of Ellen Brook
Swan River (bottom left)                                 as it flows through the gauging station weir



Nutrient summary: concentrations, loads and targets
Year                                   1994       1995       1996        1997       1998           1999        2000     2001         2002           2003      2004       2005       2006
Annual flow (GL)                       22.9       45.3       48.6        17.4       2.1*           37.9        28.3     13.5*        15.5           27.8      12.2       31.3        7.5
TN median (mg/L)                        2.3        2.0        2.2         1.8        2.0            2.3         1.8      1.9          1.7           1.95       1.7        2.3        1.3
TP median (mg/L)                       0.56       0.52       0.52        0.35       0.39           0.49        0.42     0.37         0.36           0.44      0.34        0.5       0.35
TN load (t/year)                       54.3       97.9       111.3       32.8       42.6           84.9        45.6     25.6         27.7           54.0      23.0       67.6       12.5
TP load (t/year)                       13.5       24.6       26.7         6.5        8.8           19.2        10.9      4.8          5.6           12.1       4.4       16.1        2.4

 * best estimate using available data            1 GL = 1 gigalitre = 1,000,000,000 litres           1 mg/L = 1 milligram per litre = 0.001 grams per litre          t/yr = tonnes per year

    insufficient data to test target          failing both short and long-term target          passing short but failing long-term target            passing both short and long-term target



                                                                                               1                           Keep our rivers healthy
 Changes in nutrient concentrations over time in the Ellen Brook
 Nitrogen                                                                                                                                                                              Phosphorus
 Trend:                                                                                                                                                                                Trend:
 Total nitrogen (TN)                                                                                                                                                                   While there appears to
 concentrations appear to                                                                                                                                                              have been a decrease
 have been gradually falling                                                                                                                                                           in total phosphorus (TP)
 since 1994 with some                                                                                                                                                                  concentrations during the
 fluctuations. To date no trend                                                                                                                                                        1994-98 period, this has not
 has been detected in the TN                                                                                                                                                           been detected as a trend. TP
 data.                                                                                                                                                                                 concentrations in the brook
 Target:                                                                                                                                                                               have shown a very similar
                                                                                                                                                                                       pattern to TN concentrations,
 Compliance with the TN                                                                                                                                                                fluctuating during the
 target in the Ellen Brook                                                                                                                                                             1994-2006 period.
 shows the fluctuating nature
 of the TN concentrations. In                                                                                                                                                          Target: The Ellen Brook is
                                                                      Ellen Brook - note poor riparian vegetation and evidence of erosion at the upper
 1994 the brook was passing                                           end of the brook. Photo: Lynette Da Silva
                                                                                                                                                                                       failing the short and the long-
 the short-term but failing the                                                                                                                                                        term TP targets and has been
 long-term TN target. In 1995                                         the short and long-term                    passing the short-term target                                         since monitoring began in
 the condition deteriorated                                           targets. This continued until              again. It is still failing the                                        1987. The short-term target
 and the brook was failing                                            2004 when the brook started                long-term target.                                                     has been met since 2004.


 Changes in TN concentrations over the 1994-2006 monitoring period                                               Changes in TP concentrations over the 1994-2006 monitoring period
                            5.0                                                                                                             2.0


                            4.0
  TN concentration (mg/L)




                                                                                                                  TP concentration (mg/L)




                                                                                                                                            1.5

                            3.0
                                                                                                                                            1.0
                            2.0

                                                                                                                                            0.5
                            1.0


                            0.0                                                                                                             0.0
                                  93   94   95   96    97   98   99     00   01   02   03   04   05   06                                          93   94   95   96   97     98   99     00   01   02   03   04   05   06

                                                                      Year                                                                                                             Year




 Nutrient fractions and loads in Ellen Brook

 Nitrogen                                                             plant and animal matter and                catchments for which there                                            reactive P (SRP). This form
 Almost all of the nitrogen                                           synthetic compounds such                   is flow data. This is due to a                                        of P is readily available for
 (N) present in Ellen Brook                                           as urea, which is used in                  combination of fairly high TN                                         plant and algal uptake and is
 is in the form of organic N                                          fertilisers. This form of N                concentrations and high flow                                          probably derived from animal
 which consists of dissolved                                          is available for uptake by                 volumes in the brook.                                                 wastes and fertilisers used
 and particulate fractions.                                           plants, algae and bacteria.                                                                                      in agriculture, horticulture,
                                                                      Particulate N is composed of               Phosphorus                                                            viticulture and home gardens.
 Dissolved organic N (DON)
 consists largely of organic                                          plant and animal debris and                Approximately two-thirds of                                           The remaining P is present
 compounds leached from                                               needs to be further broken                 the phosphorus (P) present                                            as particulate P, which is
 peaty sub-soils, degrading                                           down to become available to                in Ellen Brook is soluble                                             not immediately available
                                                                      plants and algae. Dissolved                                                                                      for plant and algal uptake.
                                                                      inorganic N (DIN), which                                                                                         Likely sources for this kind
                                            NH4+                      consists of ammonium –                                                                                           of P include organic waste
                                                 NOx                                                              Particulate P
                                            3%
                                                 4%                   NH4+ and N oxides – NOx,                            31%
                                                                                                                                                                                       material and sediment-bound
                                                                      makes up the remaining N                                                                                         forms of P.
                                                                      and is readily available to
                                                                                                                                                                                       The Ellen Brook has the
                                                                      plants and algae. NH4+ and
                                                                                                                                                                                       highest median TP load
                                                                      NOx are derived from animal
                                                                                                                                                                                       (2002-06) of the eleven
                                                                      wastes and fertilisers used
                                                                                                                                                                                       catchments which have
                                                                      for agricultural and gardening                                                                       SRP
  Organic N                                                                                                                                                                            flow data. This is due to
       93%                                                            purposes.                                                                                            69%
                                                                                                                                                                                       a combination of high TP
                                                                                                                 Average composition of
                                                                      The Ellen Brook has the                                                                                          concentrations and high flow
 Average composition of nitrogen                                                                                 phosphorus (P) in Ellen Brook
 (N) in Ellen Brook over the 2002-
                                                                      second highest median TN                   over the 2002-06 monitoring                                           volumes in the brook.
 06 monitoring period                                                 load (2002-06) of the eleven               period



                                                                                                             2
CATCHMENT NUTRIENT REPORTS 2006
   Seasonal variation in nutrient levels in Ellen Brook
   Nitrogen                                                                    DON and NOx discharge into                                                   Phosphorus                                                                   The exact reason for the
   TN, organic N and NOx                                                       the brook also contribute to                                                 TP, SRP and, to a lesser                                                     increase in TP, SRP and
   concentrations are seasonal,                                                N concentrations. As rains                                                   extent, particulate P                                                        particulate P concentrations
   increasing in autumn through                                                ease in August, the amount                                                   concentrations vary                                                          during October to December,
   winter and falling in spring.                                               of N being transported to the                                                seasonally, increasing in                                                    and the increase in TN and
   These increases coincide                                                    brook starts to fall. The N and                                              response to winter rains (and                                                organic N, is unclear. It
   with flushing of DON and                                                    P data collected in January                                                  rising groundwater levels)                                                   is possibly due to evapo-
   NOx from surface soils                                                      and February are from the                                                    and falling again as rainfall                                                concentration combined with
   and the surface transport                                                   unusually high summer rain                                                   eases. SRP is transported                                                    algal growth taking up the
   of particulate material                                                     event in 2000 that caused                                                    to the brook by groundwater                                                  dissolved fractions. At the
   (containing particulate                                                     the brook to flow in a period                                                discharge and sub-surface                                                    same time, cows are entering
   organic N). NH4+ is not                                                     when it would normally be                                                    and surface runoff. It has                                                   the brook more frequently
   seasonal, as most of it                                                     a series of pools. The exact                                                 been suggested that the                                                      for water, leaving manure
   undergoes oxidation of                                                      reason for the increase in TN                                                soils in some areas of the                                                   and trampling the beds and
   nitrate (NO3-) in the soils                                                 and organic N in November                                                    catchment are incapable                                                      banks. This is potentially a
   before reaching the brook.                                                  and December is unclear and                                                  of retaining any more P,                                                     localised phenomenon as
   Seasonal rises in regional                                                  is discussed in more detail                                                  so any input of P (such as                                                   the sampling site is in a pool
   groundwater levels, resulting                                               under ‘Phosphorus’.                                                          fertilisers or manure) is                                                    frequented by cows in drier
   in increased groundwater,                                                                                                                                transported to the brook.                                                    periods.

   Nitrogen seasonal variation over the 1994-2006 monitoring period                                                                                         Phosphorus seasonal variation over the 1994-2006 monitoring period

                                    5.0                                                                          2.0                                         Phosphorus concentration (mg/L)   2.0                                                                         2.0
                                                            TN




                                                                                                                                                                                                                                                                                 Flow (cubic metres per second)
                                                                                                                       Flow (cubic metres per second)




                                                                                                                                                                                                                   TP
    Nitrogen concentration (mg/L)




                                                            Organic N
                                    4.0                                                                          1.6                                                                           1.6                 SRP                                                     1.6
                                                            NH4+
                                                                                                                                                                                                                   Particulate P
                                                            NOx
                                                                                                                 1.2                                                                                               Flow                                                    1.2
                                    3.0                     Flow                                                                                                                               1.2


                                    2.0                                                                          0.8                                                                           0.8                                                                         0.8


                                    1.0                                                                          0.4                                                                           0.4                                                                         0.4


                                    0.0                                                                          0.0                                                                           0.0                                                                         0.0
                                          Jan   Feb   Mar    Apr May     Jun   Jul   Aug Sep   Oct   Nov   Dec                                                                                       Jan   Feb   Mar   Apr May     Jun   Jul   Aug Sep   Oct   Nov   Dec

                                                                           Month                                                                                                                                                     Month




                                                                 Photo: Lynnette Da Silva




                                                                 Photo: Lynnette Da Silva                                                                                                                                                                      Photo: Lynnette Da Silva

Photographs of Ellen Brook: (Top left) Cattle grazing is one of the land uses in Ellen Brook. In some areas cows have unrestricted access to the brook for water. (Bottom
left) Electrofishing in Ellen Brook. (Right) Ellen Brook near the Vines Resort. Note the sparse riparian vegetation.




                                                                                                                                                        3                                                          Keep our rivers healthy
 Local nutrient reduction strategies for Ellen Brook
 The Ellen Brockman Integrated Catchment Group is
 active in the Ellen Brook Catchment and is involved        The Healthy Rivers Program
 in the following activities:
 •	 Installation of more than 150 kilometres of             The Healthy Rivers Program aims to protect the environmental
    streamline fencing along the main channel and           health and community benefit of the Swan Canning river system
    tributaries of Ellen Brook with stock crossing          by improving water quality. This is achieved through a ‘catchment
    points to prevent stock damage to riparian              to coast’ approach.
    vegetation and banks. This also reduces erosion
    and the amount of animal waste being deposited
    into and near the brook.
 •	 Revegetation of more than 300 hectares of land
                                                            Drainage Nutrient Intervention Program
    with approximately one million native vegetation        In 2006 the Minister for the Environment announced $1.437
    seedlings. Native revegetation stabilises banks,        million in funding over four years for on-ground drainage works to
    lowers water tables, reduces soil erosion,              reduce nutrients in Ellen Brook Catchment.
    provides wildlife habitat and utilises some of the
    nutrients that would otherwise move into the            The Drainage Nutrient Intervention Program (DNIP) will
    groundwater and brook.                                  implement nutrient reduction works throughout the catchment in
                                                            partnership with Ellen Brockman Integrated Catchment Group
 •	 Conducting workshops and field days of                  and local government.
    catchment management issues to increase
    awareness in the community. The catchment
    group also encourages landholders to change
    behaviour in fertiliser use, soil health and
    establishment of perennial pastures.                    Coastal Catchments Initiative
 •	 The construction and monitoring of nutrient             In June 2006 the Swan Canning river system was identified
    intercepting structures.                                as a hotspot for water quality issues as part of the Coastal
 •	 Incorporation of catchment management plan              Catchments Initiative (CCI). The CCI seeks to significantly reduce
    objectives into local government planning               pollutant discharge in agreed hotspots, specifically reducing the
    policy. This promotes land use planning and             N and P inputs to the river system.
    decision making based on land capability within         Through the CCI, the Swan River Trust is responsible for
    environmental constraints.                              coordinating the Swan Canning Coastal Catchment Initiative
 •	 Ongoing water quality monitoring to identify            and preparing a Water Quality Improvement Plan (WQIP) for the
    areas of high nutrient concentration targeting          Swan Canning river system along with an update of the Ellen
    future strategic on-ground works.                       Brook Catchment Management Plan.
                                                            The WQIP aims to guide investment to reduce nutrient input
                                                            during the next seven years using a comprehensive decision-
                                                            making framework. The WQIP will complement other Trust
                                                            initiatives, such as the Healthy Rivers Program.




                      Summary
                      Positive signs                                         Concerns
                      Since 2004, the Ellen Brook has passed the short-      The Ellen Brook has the highest current TN and
                      term TN target again. While TN concentrations          TP concentrations of all the catchments monitored
                      have not decreased enough to be detected as a          (2002-06). It also has the highest median TP
                      trend, there is evidence that they may be declining.   load and the second highest TN load of all the
                      Only a very small portion of the TN in the brook       catchments for the same period. A high proportion
                      is present as dissolved N which, of the forms          of the P present is in the form of SRP, which is the
                      monitored, is the one most available to plants and     form most readily used by plants and algae.
                      algae for uptake.




                                                                4
CATCHMENT NUTRIENT REPORTS 2006

				
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