THE Mary River is four degrees warmer now compared to this time last year, according to data retrieved at Traveston Crossing on Tuesday.
Working their way from upstream of Conondale to River Heads, workers from the Mary River Catchment Co-ordinating Committee tested water from selected sites along the river as part of the Mary River Catchment Crawl.
Tuesday's water temp measured 28.3 degrees compared to last year's reading of 24.45 degrees.
Mary River Catchment Co-ordinating Committee's Tanzi Smith said the rise in temperature could be due to a number of environmental factors.
"It could be a combination of different things," Ms Smith said.
"It could be the fact that we had a warmer winter and a pretty hot start to spring so far.
"The air temperature has been higher and we have not had a lot of flow in the river.
"Often when it rains the river will cool down.
"But, it is well and truly above what is considered healthy."
If not addressed, the rise in river temperature could have devastating consequences for life in Mary's system.
The river's most iconic and endangered species, the Mary River cod, will not breed in warmer water.
"The Mary River is the only place it (Mary River cod) occurs naturally so it is really important we look after him here," Ms Smith said.
"There is no way they would breed at that temperature.
"They need it to be around 20 to 21 degrees."
Ms Smith said there was more people could do to ensure the species survival.
"There are a lot of people out there that are being very proactive about being careful how they manage their water way frontage," she said.
"That is things like managing stock access and controlling weeds.
"There is also the issue with the cod that people do catch them.
"It is illegal to take them.
"But this time of year is their breeding time.
"So we really encourage people not to target them."
Aside from breeding, water temperature influences oxygen levels and affects the rate of plant growth. Warmer waters are more likely to induce algal blooms.
During their catchment crawl, the MRCCC also tested the river for other vital health indicators such as E. coli, pH and sediment levels.
Aside from the rise in temperature, Ms Smith said all the other data was similar to last year.
She said human action can be taken to help cool the river down.
"If you get more trees along the river bank you get more shade," Ms Smith said.
"That makes the water cooler."
"Continuing to make sure we have good vegetation and wide buffers on the river is really important to keeping the banks stable.
"This flows on to water quality."
The year's Mary River Catchment Crawl coincides with Spring in to Mary River Month.