Collie River South Branch - Long Pool

River condition at the Long Pool site on the Collie River South Branch (site code: CR223COLL1, site reference: 6124027) has been assessed on several occasions as part of the Healthy Rivers program. The most recent survey was undertaken in March 2022.

Healthy Rivers assessments are conducted using standard methods from the South West Index of River Condition (SWIRC), which incorporates field and desktop data from the site and from the broader catchment. Field data collected included the following indicators, assessed over about a 100 m length of stream:

• Aquatic biota: fish and crayfish community information (abundance of native and exotic species across size classes, general reproductive and physical condition)
• Water quality: dissolved oxygen, temperature, specific conductivity, and pH (logged in situ over 24 hours), as well as laboratory samples for colour, alkalinity, turbidity, and nutrients
• Aquatic habitat: e.g. water depth, substrate type, presence of woody debris and detritus, type and cover of macrophytes and draping vegetation
• Physical form: channel morphology, bank slope and shape, bioconnectivity (barriers to migration of aquatic species), erosion and sedimentation
• Fringing zone: width and length of vegetation cover within the river corridor and lands immediately adjacent, structural intactness of riparian and streamside vegetation
• Hydrology: measures of flow (velocity) at representative locations (compared against data from stream gauging stations within the system)
• Local land use: descriptions of local land use types and activities (compared against land use mapping information for the catchment)

All the Healthy Rivers assessments are listed below:

• 2022 – summer/autumn (March 2–3): Healthy Rivers
• 2018 – summer (February 21–22): Healthy Rivers

Other departmental data: The Collie River - South Branch Gauging Station (site reference: 612034) is about 10.5 km downstream of the Long Pool site. The gauging station is owned by the Department of Water and Environmental Regulation (the deparment) and has been in operation since 1952.

Search the site code or site reference in the department’s Water Information Reporting (WIR) system to find data for this site and nearby sampling points (flows, surface water quality, groundwater monitoring, department’s meteorological data). See also the Bureau of Meteorology website for additional meteorological data for the area.

The species captured during each of the sampling events are provided in Table 1. The table includes a list of all species previously reported in the subcatchment, which provides an indication of species that may occur at the assessment site. This list is only indicative as differences in habitat within a subcatchment naturally influence species distributions, and variability in methods between sampling programs can affect the species caught.

Seven species of fish and crayfish were captured in the March 2022 sampling event. This includes three endemic freshwater fish (western minnow, western pygmy perch and freshwater cobbler), two non-native freshwater fish (eastern gambusia and redfin perch) and two endemic freshwater crustaceans (smooth marron and south-west glass shrimp).

Nightfish were absent from the March 2022 assessment, and gilgie were absent from February 2018 and March 2022 assessments. The absence of these species during the low-flow period in March 2022 is not considered to be of immediate concern as healthy populations of other endemic freshwater species were present (i.e. the site retains good water and habitat quality). The lack of detection is expected to be related to low sampling effort (i.e. species are present but were not detected, or species had migrated away from the site temporarily). Further investigation may be required if they continue to be absent from future assessments.

The photos of fauna provided are linked to more information about each species, including maps of where each species is expected across the South West.

Note: collection of fauna from inland aquatic ecosystems across Western Australia requires a licence from the Department of Primary Industries and Regional Development (DPIRD) and the Department of Biodiversity, Conservation and Attractions (DBCA). All species collected must be reported to these agencies as part of licence conditions.

Only fish and freshwater crustaceans (crayfish and shrimp) that typically inhabit river channels are targeted by the standards SWIRC sampling methods; however, other species are periodically captured in traps and/or observed (e.g. turtles, rakali native water rats, tadpoles). The following non-target species were identified:

• south-western snake-necked turtle (Chelodina oblonga) – one individual reported in 2018
• rakali water rat (Hydromys chrysogaster) – one individual recorded in 2018 and fresh footprints were recorded during the March 2022 assessment (unfortunately the motion-sensor camera that would have recorded the rakali was stolen). The rakali is a Priority 4 species under the 2016 Biodiversity Conservation Act meaning it is a rare or near-threatened species in need of monitoring.

Rakali footprints at Long Pool, March 2022.

For more information on these and other aquatic species please see the River Science fauna page.