Map: monitoring locations in Hunters Creek
Parameter graphs for these regions are based on results measured using field water quality probes, which measure less parameters than laboratory sampling. Some laboratory samples are gathered where required however fewer parameters are tested for and hence there are less parameters displayed on the website.
What is alkalinity?
Alkalinity is a measure of the buffering capacity of water, or the capacity of the water to neutralise acids and resist pH change. It is expressed in milligrams per litre as calcium carbonate (mg/L as CaCO3) and is present in the water predominantly due to the weathering of carbonate minerals in the catchment.
Alkalinity tends to increase in a water body when inflows to the River Murray are low. Alkalinity decreased in Hunters Creek during flood inflows from the River Murray and tributaries which are dominated by rainwater with low alkalinity levels. Alkalinity can be reduced or completely consumed as acid is released from acid sulfate soils which have become exposed and then been rewet. When water acidification occurred in some areas (e.g. Boggy Lake & Tributaries) of the CLLMM during the 2007-2009 hydrological drought, limestone was added to restore the alkalinity.
Past alkalinity levels
Historically, alkalinity levels within this region have been between 80 and 250 mg/L as CaCO3. During the 2007-2009 hydrological drought, alkalinity was below 25 mg/L as CaCO3.
What is pH?
pH is an indicator of acidity or alkalinity. pH is a logarithmic scale and an increase or decrease of one pH unit is a 10 fold change. Neutral water has a pH of 7, acidic solutions have values between 0-6 and alkaline solutions have values between 8-14.
pH can increase when there are low inflows in the River Murray, and consequently minimal flushing. pH can decrease during River Murray and tributary flood inflows as rainwater has a lower pH. pH can also decrease if exposed acid sulfate soils become rewet by rainfall or rising water levels.
Past pH levels
The pH in Boggy Creek is typically between 7and 9. During the 2007-2009 hydrological drought, the pH remained relatively stable across many of the sites. However, acidic water (pH 2 - 4) was identified in several fringing areas following the exposure and rewetting of acid sulfate soils. Since rewetting the pH of surface water has returned to neutral conditions.
What is salinity?
Salinity is a measure of the amount of dissolved salts in the water. Saline water conducts electricity more readily than freshwater, so electrical conductivity (EC), measured in micro siemens per centimeters (µS/cm) is routinely used to measure salinity.
As salinity increases, it may become harmful to native freshwater organisms. Salinity increases occur as water evaporates from the Lower Lakes (highest in summer) and also during times when inflows to the River Murray are too low to flush the salt out over the barrages and through the Murray Mouth. Salinity decreases occur when rain falls directly onto the water body and catchment, and during times of high inflows in the River Murray and other tributaries which flush salt from the Lower Lakes.
Past salinity levels
Prior to the 2007-2009 hydrological drought, salinity in Boggy Creek was representative of that seen in Lake Alexandrina and was on average less than 700 EC. During the 2007-2009 drought, levels reached as high as 16000 EC in Boggy Creek. Seawater has a salinity of approximately 55,000 EC.