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Thursday, 08 November 2012 08:09

Watershed studies continue for County of Lethbridge

Written by  Stephanie Labbe
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Janet Scott (right) a biologist with Stantec is doing a research study on the different species in the Little Bow river at the WEB's research site. She electro shocks the fish for her helper Emmanuel Aberia to scoop them up and observe the fish. Janet Scott (right) a biologist with Stantec is doing a research study on the different species in the Little Bow river at the WEB's research site. She electro shocks the fish for her helper Emmanuel Aberia to scoop them up and observe the fish. Photo by Stephanie Labbe

Every year, the County of Lethbridge holds an agriculture tour to highlight some of the projects being worked on throughout the county.

The tour has been going for more than six years and this year one of the stops made on the tour was at a Watershed Evaluation of Beneficial Management Practices (WEB) at the Little Bow watershed located within the Oldman River basin.
It’s a national program that started in 2004 by Agriculture and Agri-Food Canada. For the first four years, the funding came from Greencover Canada then through Agriculture Canada and Ducks Unlimited.
There’s a WEB’s watershed in every province in Canada except Newfoundland.
“The objective is to evaluate BMPs (beneficial management practices) in terms of biophysical and their effect on the environment. Number two, the economic costs and benefits and number three, we also did hydrological modelling using computer models to try and scale up what we’re finding at this watershed level, so we can extrapolate back to other parts of the prairie provinces and other regions,” said Jim Miller, a research scientist with Agri-Food Canada.
In the Little Bow watershed, scientists have been evaluating five different BMPs including, streambank fencing; off-stream watering without fencing; buffer strips (grass buffers) to filter run-off; conversion of greencover where some fields had barley and were converted to an alfalfa grass mix and manure management where they compared applying feedlot manure based on phosphorus instead of nitrogen.
For streambank fencing, the fencing was installed in 2001 as part of the Oldman River basin water initiative.
The researchers have been looking at the effects of the streambank fencing on the environment, mainly on the river, the riparian zone, the species that live in the river, and the associated cattle-excluded pasture.
There’s a water trough along the north side and the south side of the research site along with a cattle crossing where the cattle can go from the north to the south pasture.
“Our study was designed to show whether the streambank fencing prevented pollution of the river by cattle ... and we did find that,” said Miller.
“Our study found that ... generally, there was no change in the (water quality of the) stream, which supported our conclusion... When you keep cattle out of the river, the fecal material is not going to be deposited directly in the (river) and the riparian (area) and they are going to be kept out of the riparian zone.”
Janet Scott, a biologist with Stantec, has been doing a fish survey in the river area of the WEB research site.
When she did a previous research study in 2009 she found the fish diversity was higher in the fence reach than the un-fenced area. That means there’s more species of fish that will be found in the fenced area.
Scott also found the evenness of those species was higher in the fenced area than the unfenced area. There’s an even number of species in that river, which is what the researchers want to see.
Scott and Emmanuel Abecia were electro shocking fish in a designated area of the river and doing a fish count while the tour stop was present.
In 2009, Scott did the fish survey as part of her masters at the University of Alberta.
In her fish study, she has been looking at the different species of fish found, the number found and their state. She looks to see if there’s any difference in the species of fish in the different reaches and measures the fish weight and length.
A new species that was found in the Little Bow River at the WEB site this year, was a trout perch that wasn’t found in 2009.
Miller explained they have looked at the aquatic insects that live on the bottom of the river and have been sampling them for about five years. Overall, those results don’t indicate the fencing is increasing the aquatic insects downstream.
Streambank erosion is another aspect the researchers have been looking at in terms of the WEB study.
Researchers have been installing metal pins into the side of the river bank by pushing them in until they are almost unseen.
Over time, the researchers check on the pins and as the bank erodes, more of the pin becomes visible.
“We found that streambank erosion on the fenced reach is two to eight times lower ... than it is on the unfenced reach and that makes sense, because you can see the vegetation that’s covering this reach when you exclude cattle,” explained Miller.
Soil chemical and physical properties in the riparian zone have also been observed in the WEB study. Miller said soil compaction was improved in the cattle-excluded area. Sometimes soil nutrients were reduced in the fenced areas.
The researchers also found the cattle-excluded pasture had some beneficial effects in terms of reducing the run-off. Because grass is not grazed and there’s a litter layer, it’s acting like a grass buffer and filtering some of the run-off.
In the last few years, soil respiration has been measured. It has been found soil respiration is higher under the cattle-excluded pasture and that reflects the plant growth on that pasture.
It’s expensive to install the fencing and can therefore cause a reduction in cash flow to the producer.
“We’re not recommending that every stream in Alberta and the provinces
be fenced, because we realize it’s expensive, so maybe fencing should be targeted to those reaches that are severely degraded or maybe the taxpayers should be helping to pay for fencing if it’s going to be protecting water quality and the public good in terms of rivers and streams and lakes,” said Miller.
Off-stream watering without fencing is another important aspect of the study that has been looked at over the years.
Cattle have been completely kept out of the Alberta WEB site pasture since 2001. One of the issues is the buildup of the litter layer in the cattle-excluded pasture, because the cattle haven’t been in there to graze that pasture.
“Overall, streambank fencing has a lot of environmental benefits, but it will reduce cash flow to the producer,” explained Miller.
Off-stream watering without fencing didn’t have as many environmental benefits as streambank fencing. However, Miller said that’s to be expected as it is not excluding cattle from the river.
Some cattle behaviour studies were done as well and those found cattle tended to drink at the off-stream watering system compared to the river.
Grass buffer strips were found to be not effective in this particular watershed, because there was a lot of run-off. It was found phosphorus was being filtered about 15 or 20 metres into the grass channels.
There wasn’t a very positive effect resulting in the conversion of barley to alfalfa in the conversion of greencover BMP.
Miller said a reason for this could have been because of the timing of the year when they did the rainfall simulations. They did it in the late summer or early fall when the crop canopy of the alfalfa wasn’t well developed.
The last BMP, manure management resulted in not getting lower phosphorus in the run-off, which is what the researchers like to see.
Miller said there were some soluble components that did get significantly lower, but overall there wasn’t a reduction. Researchers aren’t quite sure why this is, but aren’t too concerned.

Read 6517 times Last modified on Thursday, 08 November 2012 08:11