LETTER TO THE EDITOR:
"Maybe you can clarify for me, but my take away from the water quality presentation was that a majority of the nutrients historically have come from the effluent out of Regina and Moose Jaw. I know in our lake Katepwa, the water quality has been significantly better since Regina dramatically improved their water treatment facilities.
COMMENT FROM DR. LEAVITT
a) "It depends of which nutrient you are talking about. For nitrogen, yes, the Cities are the main source of N, particularly Regina, and Yes, the upgrade has reduced total N pollution to downstream lakes by about 50%. For phosporus, non-point sources are likely still the major sources (the wastewater upgrade in 2016-17 only removed more N and had very little effect on P). There are some differences of opinion on the relative importance of N and P in degrading prairie water quality. I think that in systems which already have high P, the addition of N can make water quality worse. However, to get the best water quality, you need to reduce both N and P inputs, ideally in tandum."
b) "Presently, there is little evidence that Katepwa Lake is any better than it was before. It might be that the water is a bit better than the long term average, but its not due to the wastewater upgrage, In fact, there is evidence to show that the effects of the upgrade will not be visible for many years. There are several reasons for this, including i) it takes approximately 2 years to get most water from Pasqua to Katepwa, especially in summer when there are blooms, ii) a lot of nutrients come from the sediments (termed "internal loading") and that has not changed, and iii) long-term monitoring shows that the lakes, including Katepwa, have been reacting to variations in temperature more than nutrients because the nutrients are not changing much)."
LETTER TO THE EDITOR - continued:
"I agree we all have to be conscientious about what flows into our river and lake system, but my take away from the presentation was the agriculture was a small percentage of the cause."
COMMENT FROM DR. LEAVITT
"As above, this is not true for P - even for N, the non-point (non-city) sources would be not less that 40% of the total influx. The issue with "agriculture" is that there are several sources (fertilizer, livestocks, erosion, land management), so its not useful to consider it as a single factor."
LETTER TO THE EDITOR - continued:
"In addition, I remember when I was growing up the lakes being full of algae in the late 60’s and early 70’s (I remember seeing a patch on Echo right by the Fort that I thought you could walk on) and this was at a time when synthetic fertilizers had not been developed."
COMMENT FROM DR. LEAVITT
"This observation is true, but not relevant. During the early 1970's, the City of Regina had virtually no modern watewater treatment and BOTH N and P enterred the Fishing lakes unprocessed (actually, organic matter was removed so that the fish, etc. would not suffocate from lack of oxygen - mineral nutrients were not removed). The water quality at the time was very poor, probably worse than at present, although the long term data does not support his positiion (its as bad now as it ever was). What the author may be referring to is a change in the proportion of buoyant (floating) cyanobacteria, which are the surface scum."
LETTER TO THE EDITOR - continued
At that time I believe they were blaming the algae bloom on livestock run off into the lakes. I also had discussed with my elderly mother-in-law prior to her passing and she said that Katepwa used to be green with algae in the 30’s. Obviously this was long before any modern farming practises.
COMMENT FROM DR. LEAVITT
"As above, it was the urban pollution, not the "modern ag" in the 1960s and 1970s. Effects of moderm ag are evident in the fossil record as early as 1890 (before SK was a province). However, effects of ag build slowly and it has taken decades for the nutrients to accumulate in the lakes (where they are now stored in the sediments).
Secondly, 'ag' is too vague a term - you have to split it as being FROM CROPS (and type), FROM PASTURES, FROM INTENSIVE LIVESTOCK, FROM DAMAGE TO WETLAND DRAINAGE. All have effects on nutrient flow to lakes, some are faster (FERTILIZERS) than others."
LETTER TO THE EDITOR - continued
I think if you research now, with the advent of zero-till farming over the last 25 – 30 years – i.e. no cultivation and continuous cropping – there is significantly less run off than there has ever been. There are more natural nutrients in the soil, way less erosion from wind and water, and the soil absorbs much more moisture (and carbon) than it used to when there was cultivation.
COMMENT FROM DR. LEAVITT
"There are a couple of points.
First, It is true that management is generally better than in the past - when we had the 1930's dustbowl, in part because of land use practices. However, that does not equate to 'everything is fine'. Fertilizers are generally added in excess of plant demand, specifically to compensate for 'losses' (to the atmosphere and water), timing of additional fertilizer has not historically been when crops needed it (rather when the 'sale' was on), and the form of nutrient was not always ideal. Things ARE better, but the problem is the AREA under cropland is vast, and so even small errors accumulate.
Second, as to Jeff's point (see PARCS UPDATE # 157.2 THAT FOLLOWS) about no tillage leading to increased runoff - as I understand it, is not entirely correct - it leads to more dissolved nutrients being run off because there is more leaf litter than in a tilled field. HOWEVER, this is the natural state of the grasslands so remains the 'target' state for grassland management over much of the world. Also, this entirely ignores the massive reduction in PARTICULATE nutrients which DO eventually end up in lakes (as silt and erosion) where they can be released as sediments (fertilize the lakes). Loss of wetlands and shoreline vegetation (riparian zone) have played a large role in this problem, as they are no longer 'trapping' the particles.
I guess my point is that I didn't take away from the presentation that agriculture was a significant contributor to the water quality, if at all. The algae is a natural occurence in the Southern Saskatchewan Lakes and has been around forever, and we made it worse with allowing effluent to flow from Moose Jaw and Regina.
An important point here is that the lakes ARE naturally green. With the exception of Diefenbaker, southern lakes would have been green, with cyanobacteria, 100s of years ago. However, they are much worse now than centuries earlier, and this is due to our actions.
LETTER TO THE EDITOR - continued
I guess my point is that I didn’t take away from the presentation that agriculture was a significant contributor to the water quality, if at all. The algae is a natural occurrence in the Southern Sask. Lakes and has been around forever, and we made it worse with allowing effluent to flow from Moose Jaw and Regina.
Agriculture is always easy to point a finger at, but I am not sure it is factual.
If you have other information, please let me know."
Resident of Katepwa
