21 September 2015…The Department of Water publishes a series of nutrient reports for the Peel-Harvey catchment. Now, the results of 20 years of monitoring nutrients in the waterways of the catchment are providing valuable data on water quality in one of the most significant strategic assessment processes ever convened for Western Australia.

The Strategic Assessment of Perth and Peel Region (SAPPR) aims to integrate management of the environment with future urban and infrastructure requirements and, according to Peel-Harvey Catchment Council (PHCC) Chair Jan Star AM, is prioritising water quality based on the monitoring results.

“SAPPR assesses the impact of proposed future development on matters of national environmental significance listed under the Commonwealth Environment Protection and Biodiversity Conservation Act 1999. It is a multi-layered process designed to deliver an effective long term and strategic response to major environmental issues in the Perth and Peel region. Water quality and its impact on the Peel-Harvey estuary is a key issue and one the State, Commonwealth and the Peel-Harvey Catchment Council are continually collaborating on to define the health of our waterways. The information in these nutrient reports will help target remediation projects in the right areas for best outcomes,” said Jan Star.

Nutrient enrichment of drainage water (eutrophication) has long posed a threat to the health of the Peel-Harvey estuary system. Dr Steve Fisher, Science Advisor at the PHCC, said eutrophication can result in increased growth of aquatic weeds, toxic algal blooms, and sometimes fish kills.

“Long-term monitoring of the annual water flow and the nutrients nitrogen and phosphorus in water conducted by the Department of Water allows us to assess whether the amount of nutrients flowing to the estuary is increasing, decreasing or remaining constant over time,” said Dr Fisher.

“The Department of Water published a series of catchment nutrient reports for the Peel-Harvey. Initially released in 2010, the reports were followed by updates containing more recent data in 2011 and 2012. Updates current to the end of 2013 have now been released for publication,” he said.

The Peel-Harvey catchment is divided into 13 subcatchments with a nutrient report for each. The status of each subcatchment is classified as Low, Moderate, High or Very High according to the concentration of nitrogen and phosphorus measured during the monitoring program.

Trends in nitrogen and phosphorus concentrations were published in the 2011 reports. Because a minimum of five years of monitoring data is required to calculate these trends, they will not be updated until 2016.

The area of land associated with various land uses is also shown in each subcatchment report. These land uses include cattle and dairy farming, cropping, horticulture, intensive animal farming and residential amongst others.

A mathematical model relating these land uses to the flow of nutrients was created by the Department of Water for each subcatchment for the 2010 reports. The modelling will be repeated in 2016 using the most up-to-date information from the monitoring program.

“This model will allow us to more accurately estimate the contribution of different land uses in the catchment to the amount of nutrients exported to the estuary, and to prioritise where we need to focus our efforts to reduce the nutrient load”, said Dr Fisher.

The series of nutrient reports published by the Department of Water can be viewed on the Peel-Harvey Catchment Council website here:
Media Contact: Jane O’Malley, Chief Executive Officer, Peel-Harvey Catchment Council, Jane.Omalley@peel-harvey.org.au , (08) 6369 8800

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