Meeting papers

                                                                                        Burgess Creek
                                                 Receiving Environment Monitoring Program
                                                                                 Annual Review 2022
The highest ration of chlorophyll a to pheophytin was measured at B1, indicating that algae is
growing and taking up nutrients. Chlorophyll a is the primary photosynthetic pigment in algae
and other aquatic plants, and its concentration is often used as an indicator of the overall algal
biomass in a water body. This is the first point within the Burgess Creek that evidence of
significant nutrient uptake is occurring within Burgess Creek. At this monitoring site there is
more chlorophyll a than pheophytin indicating that conditions are better for the uptake of
nutrients such as phosphorus and nitrogen, which are essential for the growth of algae. It is
possible that the presence of the culvert under David Low Way has acted as a dam, slowing
the flow sufficiently for growth and uptake to occur, or that the damming effect of the Pacific
Ocean has prevented releases, except during low tide. Sufficient nutrients have been
measured between monitoring site B3 and B1 to sustain high algae growth but concentrations
of chlorophyll a are only measured at B1 resembling an algae growth phase or bloom. The
chlorophyll a and chlorophyll a:pheophytin ratio show that the treatment strategy reduces the
residence time of nutrients in Burgess Creek, limiting the ability of algae to use nutrients
released from the Noosa STP. Without these nutrient flows, the western branch and lower
Burgess Creek would be more like monitoring site B8 than B3 to SW3, highlighting the
complexity of the relationship between nutrient levels and algal growth.

Long term trends are indicative of a catchment wide increase in total nitrogen since 2015, with
the exception of B2 and SW3 whilst total phosphorus and ammonia have no clear long-term
trend within the data collected from any of the monitoring sites. Despite the increased nutrient
concentrations, no significant lasting ecological impact was observed in the receiving
environment. The concentrations of these nutrients were found to decline downstream
towards the point of discharge into the ocean, which is consistent with the typical impact of an
STP outfall on water quality within a freshwater waterway. The highest concentrations of
nutrients are typically observed immediately downstream of the outfall, with nutrient levels
decreasing as the distance from the outfall increases. There could be several factors
contributing to the catchment-wide increase in total nitrogen over the last 7 years. One key
factor that could potentially impact Burgess Creek is the increasing urbanisation and
densification of residential areas. This could have a twofold effect on the creek. Firstly, it could
introduce more nitrogen-rich runoff into the creek, which could alter the natural catchment and
waterway processes. Secondly, it could increase the volume of stormwater runoff, which could
further exacerbate the impacts of nutrient-rich runoff. Another possibility for the changes in the
Burgess Creek catchment is that La Nina weather patterns in recent years may have raised
groundwater levels. The composition of the Burgess Creek catchment, which is entirely
composed of sand, makes it behave differently than other nearby creeks and waterways with

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