Fish-friendly diversion screens

The land is very important. The river is super important. And we've all got to do a little bit better I think to um look after it. It's a beautiful environment. My name is Jim Horga and Background. I've lived at Elderly for over 60 years. We're having trouble in on the Darling at certain times with um fish eggs and lice and whatever blocking up filters. With sand filters they're very good but they're very expensive. So uh we're looking for something cheaper and that was more environmentally friendly because they can do damage to the small fish and the shrimp and the eggs and what's going back.

Whats going back. Most native fish even the big ones like Maricota Golden Perch they start life as tiny little eggs like millimeters big. And at some stage those eggs or the larvae that hatch from those eggs are going to be moving downstream with flow that unfortunately brings them into contact with pumps. Pumps can take them out of the water. They're too tiny they're not good enough at swimming to get out of the way. So lots and lots and lots of baby fish are removed by pumps which means there's fewer fish surviving and growing in our rivers where they should be. So.

How it works. The river screen is a it's buzzer primary filter so it's out actually filtering the water before it gets to your pump. So you're not actually getting um or you're fishing that going into your into your main line and blocking your other filters up. So it's a it's a floating suction. It sucks off the top four inches of water. It floats up and down with the river height. So if the river rises six foot will the river screen will rise up with the water level and drop down with the water level. And basically the way the river scream works it it's a spinning filter so it spins and constantly self cleans itself. Uh shrimp fish fish larvae they just can't get through it. So yeah they're staying in the river where they should be.

Benefits. This scream when I heard about it I just my eyes just opened up in excitement because this is a way that we don't even have to remove anything from the river itself. Everything stays in the river. The only thing we can remove is the water we need and put it where exactly we want it. It helps us use less water be more efficient and more effective. If this screen can work and work well with grip irrigation it's it's going to save just that much money and help the environment and help everybody. So it's a win win.

Conclusion. So irrigators are picking this technology up worldwide. It's good for the irrigator themselves because cleaning pumps can be frustrating if not very expensive in terms of time and dollars. So a farmer that puts screen on their pump is not making only making an investment for their business they're also contributing to the health of the river system. If we all do our bid then overall all the things that threaten fish in the river system can be addressed and this is the bit the farmers can do very simply. It's a big cost initially outlay but the benefits for them long term in terms of money is good and for the river fantastic. If we don't look after the Darling River itself I don't think anybody else is going to. It's up to the farms themselves to live along the Darling. We must keep up with the times and look after our river. This looks like a good way you.

We need this river to work. We need the Murray to work. We need the whole system to work. But we need to try and find a balance or what find ways to make the impact on fish less.

Go back to basics. There's over 50 species of fish in our Murray Darling system. But over half of those fish are threatened and all of them all the native fish have declined in abundance since uh we started to use this river as a working river.

So we made a whole bunch of changes which were necessary and that's how we feed the nation. But we're now recognizing there's impacts to that. So one of my jobs is to try and work out how can we mitigate those risks or mitigate those impacts and in particular today we're talking about screening.

All of our native fish lay eggs and those eggs vary from half a millimeter or smaller to maybe a couple of millimeters big. So they're tiny. Once they hatch pretty much all of those species of fish in the basin require some level of flow to make them drift downstream.

Flowing rivers bring those drifting eggs and larvae into contact with your infrastructure which is the problem that we're trying to address here. These drifting larvae a couple of millimeters big they don't swim great they're not going to get out of the way they get up they go done. And if they survive it if they go into a dam somewhere they're okay but they're not coming back to contribute to the next generation.

So what we're doing with these modern screens is we're actually changing the hydraulics of the intake of the screen so we actually reduce the flow or the velocity of the water reaching the screens. If we get anything impinged on this surface we have a problem. So it's quite important when we look at a screen that we actually have a screen that's cleaning. So you saw water cleaning before the way this screen works is basically there's an impeller in here as the water is being drawn through the pump through the screen the screen starts to rotate on its own.

The company that supplies the screens is River Screen here in USA. We've been importing them now for about six years I believe. We've probably got three or four hundred units working in throughout the country. As everyone knows in irrigation once you start losing pressure you're not watering properly. So that's why we went to this system.

So there's a set of jets on the inside that blow up through the mesh to keep it clean and a set on the outside on the water drive ones just to rotate the screen and blow anything off the outside that sits there.

I live on the Darling River. We need a healthy river so we need the native fish if we can. But also it gives us benefits upstream in the irrigation system and the filters along it uh reduce use wear and it's a cleaner cleaner system so it makes makes our life easier on the farm.

The time that we take to physically clean the back up filters and the filters through the the drip irrigation system is reduced tenfold and also the cost of of doing that.

The true reason number one reason we went with a fish screen and we liked the idea of it is for our sustainability journey. We've got a great relationship with Kaye and the Local Land Services team here and then when the funding come up we thought it was a it was a no-brainer. So we we went with this design probably more so from uh in our opinion we like the lack of power um lack of maintenance and it just seemed like a really easy fit to our current design.

We've got the rail system the standard centrifugal pump up the top of the embankment and really it's a flange change and a bolt-on.

So beyond that sustainability benefit we really wanted to look at also operational benefits which we've all spoken about in detail being filtration. Currently we're back flushing 45 out every 45 minutes on our primary filtration and our field filters with cleaning manually every month roughly.

We know what our current state is and all of our pressure data our back flushes is all trended so we can go back over that and and build some some cost benefits out of that. So that's a key thing that we're really interested in understanding and then what we see that doing is driving into our other sites. So we've got a lot of sites with similar infrastructure similar pump rail systems where ideally you know it's change out our current screen which is a standard 10 mil punch hole aperture arrangement with a screen like this and um and then see the benefits across all of our sites.

The funding assistance from Local Land Services probably pushed me over the line to order order the screens and the fish screen has been a real positive. It's made my life easier the river's um better off my farm's better off and and the less worries and and expenses for the farm.

Without the screens pumps can suck up millions of fish throughout the basin per year depending on flow rates depending on how good you speak and this is a pretty simple way to keep a bit of distance between the fish drifting past and the actual pump the off-take. It gets frustrating when you get rocks thrown at you for being an irrigator just for being an irrigator when all you're doing is your job feeding the nation.

Um so if this is one of the ways the government can help incentivize an improvement and it gets you a bonus as well through dollars and efficiencies and less resources then that's a win-win. And the third win is theoretically if we get more fish staying in the river we'll have more fish to go fishing for in the next 10 years and our kids and our grandkids will continue to be able to fish recreationally for these guys.

If this gets picked up and and starts getting laid out across the mountain basin itself that's one of the big threats to fish that we don't have to worry much about anymore.