High Nutrient levels in Canal Highlight Concern Over Water Entering Lake

The Care Group have requested an investigation into record algae levels after rain events in late January. The rain events coincided with significant inputs of dirty water from the canal. Unfortunately, neither Council or Griffith tested the inflow of water during the recent rains. Council however have been testing the canal water at specific high tide events and advised of high nitrogen levels  (red arrow)

The graph shows the average yearly concentrations in LHM which are well above the Water Quality Objectives (dotted red line) for the Nerang Catchment including LHM.

No doubt, nutrient levels in the lake would also be elevated to a certain degree but ongoing and future works including gully baskets, Phoslock applications and catchment management improvements are all aimed at controlling and reducing  nitrogen levels toward the water quality objectives of a healthy lake.

The concern is that unknown inputs from the canal including high nitrogen levels are going to reduce the effectiveness of any lake based improvements.

Clearly the unknown inputs of dirty, high nutrient and possibly polluted waters from the canal may not beneficial to the long term health of the lake. We request further investigation of lake inflows to determine the suitability of a one-way valve.