Steps to improving water quality

At the Teagasc National Dairy Conference last week Teagasc director of research, Pat Dillon outlined how water quality can be improved in Ireland.

He firstly explained how water quality is measured by the Environmental Protection Agency (EPA).

He said that surface water such as rivers, lakes, estuaries and coasts are classified into high, good, moderate, poor or bad depending on their ecological status.

There are a number of factors determining ecological status. Biology is the first one and this looks at the living things in the river such as insects and invertebrates.

These are typically assessed in rivers every three years by a kick test.

The person carrying out the test will stand in the river and kick up some of the stones and gravel on the river bed and use a small net downstream to catch whatever is disturbed.

Invertebrates have different tolerances to water quality, so by seeing what lives in the water is a good proxy for determining how good the water quality is.

The next thing is water quality and Pat says this is measured by the phosphorus, nitrogen and ammonia levels in the water as well as looking for any chemical residues.

When two out of three of the nutrient parameters fail to meet the standard then good nutrient status is deemed to have not been met.

In other words, if phosphorus and ammonia are good but nitrogen is poor, then the river’s nutrient status is good. But if both phosphorus and nitrogen are poor, then the water quality in that river is deemed to be poor.

The third area is hydromorphology, which he described as being the flow of the river which is affected by weirs, dams, dredging and embankments, etc.

He said that the overall classification for a river will be determined by the lowest score in any of the three categories.

So if biological status and hydromorphology are both good, but if water quality is moderate, then the river will be classed as moderate and vice versa.

For a water body to be considered good, it needs to be at least good or high in all three areas.

The EPA measure water quality in three-year cycles and in the last report published for the six-year period 2016 to 2021 showed that 54% of surface waters had good or high ecological status.

Pat says that the main issue with the rest of the rivers was too much N and P in rivers.

He said that phosphorus issues tend to be associated with heavy soils where overland flow is the issue. On nitrate, he said this is an issue affecting free-draining soils in the south and southeast.

Catchments

Pat presented data from eight catchments showing the proportion of the water bodies in each catchment at the different ecological statuses and this is summarised in Table 1.

Looking at the high and good status, 67% of the Bandon/Ilen waterbodies are considered high or good while only 32% of the Boyne or 36% of the Suir achieved that status in the monitoring period 2016 to 2021.

He says there are much bigger challenges for water quality in these areas.

In the Blackwater catchment, 66% of the water bodies had good or high status.

This is a large catchment covering a huge area of Cork and Waterford and one of the most intensively farmed regions in the country. Rising in Ballydesmond on the Cork/Kerry border, the Blackwater flows east through Mallow, Fermoy and on to Cappoquin before entering the sea at Youghal.

Every drop of rain between the top of Galtee mountains north of Mitchelstown, across to Gneevguila and Rathmore in Kerry and then east to Youghal is part of the Blackwater catchment as all of the streams and rivers in this area end up flowing into the Blackwater, including the Arrow, Awbeg, Funshion and Bride rivers.

Pat says that the proportion of the catchment at high or good status has declined over successive testing periods.

There was 86% of the water bodies in good or high status in the 2007 to 2009 period, dropping to 71% in 2010 to 2015 and while it improved in the 2013 to 2018 period to 77% it fell again to the current status of 66% in the 2016 to 2021 period.

However, Pat says that the shift was from good to moderate status, meaning that it wouldn’t take much to get them back into good status again.

He referenced the 2018 drought and decisions around fertiliser use as being detrimental to water quality nationally because it increased the N balance:

“We did everything wrong in 2018 when we have a nitrogen balance of almost 200kg N/ha but we got this back to 140kg N/ha last year. That’s really important in terms making progress in reducing N losses,” he said.

Actions

Pat said increasing slurry storage on farms is a key step towards improving water quality as it will allow for better use of nutrients.

He says the storage requirements are likely to increase by 20% based on new on-farm research data indicating 0.41m3 per cow of storage is required per week, up from the current figure of 0.33m3/cow/week.

“I think there’s real advantages of increasing slurry storage. Putting slurry out in early spring at sub-optimal soil temperatures or when soils are waterlogged just means you’re not using that slurry, you’re wasting it.

“Increased slurry storage is really important in terms of maximising your replacement value of P and K and reducing nutrient loss to water and reducing nitrogen surplus by replacing chemical N on your farm,” he said.

He says point source is another problem, with the research showing that there is 20l to 40l of water per cow per week getting into water tanks.

“Point source is an issue on farms and we need to improve it.

We’re talking here about gutters and downpipes being repaired, we’re talking about clean water being diverted away from yards and concrete, we’re talking about restricting animal traffic on farmyards and we’re talking about reducing the area of soiled water,” he said.

Pat said that these issues apply to all farms, not just dairy farms in these catchments and said that fencing off of watercourses and reduced point source pollution is very important on drystock farms, even lowly stocked ones.

For tillage farms, he said that maintaining overwinter cover is a key step to reduce nitrogen leaching and retain nutrients in the soil.

In summary, Pat said that water quality in Ireland was good in an EU context but he says there is considerable opportunity for improvement and that improvements will be necessary to maintain the nitrates derogation.

He said that we need to move towards a catchment approach, referencing a recent trip to New Zealand where he said they are making big progress on water quality by focusing on catchments and targeting specific problems in that catchment.

What is striking over the last six months is that the conversation on water quality has moved on from blaming others for poor water quality towards finding solutions for farming’s contribution.

Pat’s presentation was a continuation of that and the attitude in the room was one of attentiveness and resolve to fix the problem.

The Teagasc vision for the immediate future is to have a lot more slurry storage on farms which will allow farmers to make much better use of slurry.

This means targeting the P and K to the fields that need it the most, rather than spreading it on dry fields when conditions are dodgy just because tanks are full.

The cost of extra storage is around €400 to €500/cow but with a 60% grant that reduces to €240 to €300/cow.

It’s not insignificant but it’s an investment in the future, provided it delivers the desired improvements in water quality.

OK, uncertainty around the derogation will remain, but if the investment isn’t made in the right areas, or if farm practice doesn’t change, then the derogation is certainly at risk.

There’s momentum among farmers to improve water quality. We probably need to broaden out the actions beyond just slurry storage. It’s good to see some progress being made on assessing and interpreting nitrogen surplus or balance. We also need the results of of river quality data to be freely available for every sub-catchment.

In short