The Ludlow River is in the central east of the Geographe catchment and is the only major waterway to discharge to the Wonnerup Estuary, an important habitat for waterbirds. The upper catchment is located in the Whicher Range National Park, an area known for its unique environmental features and floristic diversity. A small portion of the Ludlow Tuart forest is also located in the lower catchment area. The river is of cultural significance to the Wardandi people and registered sites of significance are found within the catchment, including a grindstone artefact site. A survey by Wetland Research Management in 2006 found a moderate diversity of macroinvertebrates and several species of native fish and crayfish including the Gilgie, Marron, Koonac, Nightfish, Western minnow, Western pygmy perch and the Mosquitofish. A River Action Plan developed by GeoCatch in 2002 outlines the characteristics, values, condition and management issues of the river system.
Approximately half of the catchment is comprised of native vegetation, located on the Whicher Scarp. The other half of the catchment lies on the Swan Coastal Plain, where the land use is mostly comprised of cattle grazing for the beef and dairy industry, turf farms, horticulture (avocados and potatoes) and tree plantations. A sand mine occurs at the base of the scarp.
Image: Land-use in the lower catchment is predominately agricultural
The headwaters of the river are in the Whicher Range. The River flows in a north-westerly direction eventually discharging at the Wonnerup Estuary. The lower reaches of the Ludlow River have been straightened and into a drain just north of Tuart drive. Since 2000, the mean annual flow for the Ludlow River is 10GL/yr of a total of 203 GL/yr for the waterways of the Geographe catchment.
The Ludlow flowing into the Wonnerup Estuary via a modified drain.
The nutrient loads in the Ludlow River are driven by agricultural land-uses. Fertiliser from dairy grazing and beef grazing are the dominant contributors, followed by point sources (three dairy sheds). Annual and perennial horticulture also deliver small proportions of the nutrient loads.
Image: Nutrients in the Ludlow River are primarily sourced from fertiliser used for dairy and beef grazing, with smaller quantities from point sources (dairy sheds).
The Department of Water and Environmental Regulation has been monitoring the water quality of the Ludlow River fortnightly since 2006. Data from 2008-2016 is presented in the table below (as data from 2008 represents data from 2006-2008). The data shows total nitrogen concentrations to be consistently above water quality targets. Total phosphorous concentrations have exceeded water quality targets since 2011.
The Ludlow River catchment is categorised as a ‘recovery’ catchment as waterways do not meet the nitrogen or phosphorus target established in the Water Quality Improvement Plan.
Trends in nutrient concentrations of the Ludlow River
There is a medium significant increasing trend in total nitrogen concentration for in the Ludlow River catchment. No statistical trend in phosphorus concentration was observed in the data.
Since 2009 programs led by GeoCatch and partners have focussed on reducing nitrogen and phosphorus entering the waterway. These programs included working with farmers to reduce fertiliser use, developing best-practice dairy effluent management and completing fencing and re-vegetation in the riparian zone. Key achievements between 2009 and 2015 include:
Fourteen landholders carried out soil testing and nutrient mapping to inform fertiliser decisions, assisting farmers to use only the phosphorous needed for the pasture growth required.
Two dairy effluent management plans were developed to support the re-use of dairy effluent, reducing nutrients entering the waterways.
Ten landholders completed 3.2km of riparian fencing and6.3 ha of revegetation with the aim to restore and protect native vegetation, prevent stock access, increase the absorption of nutrients and to reduce sedimentation and pollution.
Further works in the Ludlow River catchment are a priority to improve water quality. For the next three years management programs will continue to focus on reducing nutrients entering the Ludlow River under the Revitalising Geographe Waterways program. Implementation of best practice agricultural fertiliser management and dairy effluent management are key goals for this ‘recovery’ catchment.
Soil testing, whole farm nutrient mapping, agronomic advice and workshops will be carried out on at least one farm in the catchment through the implementation of the ‘Smart Soils’ project. At least two effluent upgrades are proposed in the catchment, reducing the dairy industry nutrient footprint in the catchment.
Monitoring the water quality of the Ludlow River will continue in the Catchment Water Quality Monitoring Program and the Water Quality Improvement Plan will be reviewed and updated.
Actions to reduce nutrients entering the Ludlow River will continue as part of Revitalising Geographe Waterways program.