Do lakes slope?

Does the Earth’s rotation have an effect too?

coriolis effect. Has to be a big lake though. Not a sink at the equator…

Thank you for your erudition folks. My next, associated, question is:

Which bit of the lake flows? Does the colder, denser water at the bottom just sit there and the upper layers are more temporary? I’m looking at Windermere at the moment, just starting on my beer as I wait for my Spanish scotch egg in the Mortal Man, Troutbeck.

That will depend on the lake.

What about the floaters from the primary effluent discharges? Does that give you a lumpy, smelly slope?

Ftfy

Windermere has two distinct basins, the imaginatively named north and south basins. If I remember correctly, it’s been a while since I looked at the Lakes Tour, but overall residence time is 280days. I think the north basin residence is 180 days out of the total. It is a 64m deep hole that has significant stratification in the summer. The southern basin appears more susceptible to mixing, but does stratify. There’s a fair bit of concern about anoxia in the north basin.. Wastwater’s residence time is close to 500 days. Most of this is linked to inputs, the Windermere catchment is huge in comparison and can experience significant flushing. In storm events the residence time can be significantly reduced.

Talking about discharges, a report I saw on the source apportionment for P in Windermere gave an equal split between sewage outfalls, private septic tanks and agriculture. This is where I find the current campaign an utter nonsense because its ire is directed solely at UU with little mention of the other sources. The private systems are utterly deplorable, I had to visit an overflowing one into Esthwaite Water – sewage flowing across a field straight into the lake, the owner blamed the farmer. Some other testing we did on known outfalls showed significant elevated P and coliforms. It’s no wonder Najas flexilis was lost from Esthwaite Water (I was part of the team that bought out the fish farm (£4.5m) and leveraged that to get UU to spend £10m on P stripping at Hawkshead WwTW, but the inputs from agriculture and private systems continue to significantly affect the water quality which then flows straight into Windermere).

Talking about discharges, a report I saw on the source apportionment for P in Windermere gave an equal split between sewage outfalls, private septic tanks and agriculture. This is where I find the current campaign an utter nonsense because its ire is directed solely at UU with little mention of the other sources.

I think there reason theres a focus on UU is because unlike septic tank owners and farmers we, the public pay UU to do the job properly. It should’t be an equal split between those 3 sources, it should be an equal split between two and the total pollution should be a third lower than it is

I disagree with that. We, the public, also pay farmers. We also pay for ameliorating the harm caused by private septic systems. Even if the levels were a third lower, they would far exceed the critical loads for an oligotrophic lake, so blaming a single factor, one that has invested heavily in ameliorating harm, is grossly unproductive. The alternative to storm overflows is that large storage tanks, similar to the old coal gas stores, would have to be installed, or that every surface water drain has to be rerouted to flow direct into the lake.

I’m not saying that UU should be totally absolved, they absolutely should be doing better. But other issues, eg increased sedimentation, also critically affect the breeding sites for Arctic char around the lake. This is caused, in the main, by unsuitable agricultural practices (I have a photo of slurry spreading in January on snow in Langdale which dumps P,N and coliforms into the lake at a time where no primary productivity is taking place).

I remember looking through some reports, once the phosphate strippers were in place and the treated effluent was cleaner than the river water flowing into the lake. It’s the storm discharges that are the primary issue from UU. I think they have also committed to invest a further £20m in attempting to further reduce impacts. There’s nothing proposed for septic tanks (the Fish Police turn a blind eye) and agriculture continues to dump tons of nutrients in the catchment with little reduction.