Flows

[Swattie87]

About a month ago we were all concerned about low flows. Everything on the USGS site was in the red or orange. Then, we got a ton of rain and everything was blown out (blue or black on the USGS site). Now, we’re back to red and orange.

I hope this illustrates the point that flows in PA are a very much “what have you done for me lately” type of deal.

 

[caddisflyer]

I noticed it looking at the streams around here. We seem to get fast flooding and then they drop back in no time. It seems like over the years MANY streams have been dewatered too. Much smaller than I recall or even non existent.

 

[Nocktavius]

About a month ago we were all concerned about low flows. Everything on the USGS site was in the red or orange. Then, we got a ton of rain and everything was blown out (blue or black on the USGS site). Now, we’re back to red and orange.

I hope this illustrates the point that flows in PA are a very much “what have you done for me lately” type of deal.

I noticed after everything had “blown out” that the forecast was much drier for the foreseeable future. There’s something very different about our pattern this year- not nearly enough little thunderstorm lines accompanying frontal changes. Instead it just gets a little blustery and pisses for 10 min maybe. Those cells are traditionally responsible for keeping Penns and other central PA creeks flowing cold and a bit murky this time of year. At least one more big blowout would be very welcome not just for the fish but also to chase the crowds who get squirrelly about wading over 700 cfs.

 

[wildtrout2]

There’s something very different about our pattern this year- not nearly enough little thunderstorm lines accompanying frontal changes. Instead it just gets a little blustery and pisses for 10 min maybe.

It was very similar last season as well. Get a good day of rain, then it doesn't rain again for six weeks, or more. We need more frequent rain. These spotty showers do nothing, we need the all day soaking rains, that seem to be a thing of the past. If anyone thinks our weather isn't changing for the worse, they'd better think again.

 

[wildtrout2]

About a month ago we were all concerned about low flows. Everything on the USGS site was in the red or orange. Then, we got a ton of rain and everything was blown out (blue or black on the USGS site). Now, we’re back to red and orange.

I hope this illustrates the point that flows in PA are a very much “what have you done for me lately” type of deal.

This is true. Now, many streams are even lower than they were before that last rain event. Some relief is expected for Saturday. Depending on what that low pressure system does along the coast, we might get a decent amount of rain into early Sunday morning. Let's hope.

 

[troutbert]

I noticed it looking at the streams around here. We seem to get fast flooding and then they drop back in no time. It seems like over the years MANY streams have been dewatered too. Much smaller than I recall or even non existent.

Which streams have been dewatered, and what do you think is causing that?

 

[Nymph-wristed]

So these are observations not any science on my part, but I think it does matter WHEN the rain comes and doesn't. Forget snow and snow pack these days in most of the state, but if it does not rain in March and April like it is supposed to, that means low water and longer days heating up shallower water with no leaf cover yet. That appears to equal a lot more algae covering rocks, and a lot more leaf litter rotting in place and not being flushed, and that is why sustained climate change seems to snowball with effects. For example, that has to affect certain bug hatches in some way, I assume, assist or hurt the sucker spawn? and other early spring events. Even if the rain comes in May, the damage has been done on some level. Freestone creeks got warmer faster this year and last, and even if they cooled off again, the disruption was a disruption and not the normal ebb and flow of rain events. Timing is everything with these odd fluctuations. Can the resident Bill Nyes weigh in?

 

[TimMurphy]

Which streams have been dewatered, and what do you think is causing that?

Dear troutbert,

I know you are familiar with Spring Creek. Walk the Paradise and observe the traditional streambank, you know, the one that is high and dry 10 feet from the current flowing water and at least 6" higher in elevation.

Development in the problem. The development in the Centre Region causes severe spikes in flow rate that quickly return to normal. I don't think I'm out of line here when I say the Centre Region loses 50% of rainfall in run-off. Precious little seems to actually get into the ground where it is most useful.

Except for choosing a place to fish following rain, CFS is a lousy gauge of actual stream conditions without some historical perspective. A flow rate of 100 CFS can flow 2 feet deep or 6 inches deep and so long as the gauge is still in the stream the flow will be the same. The stream conditions obviously won't be.

Regards,

Tim Murphy

 

[TimMurphy]

So these are observations not any science on my part, but I think it does matter WHEN the rain comes and doesn't. Forget snow and snow pack these days in most of the state, but if it does not rain in March and April like it is supposed to, that means low water and longer days heating up shallower water with no leaf cover yet. That appears to equal a lot more algae covering rocks, and a lot more leaf litter rotting in place and not being flushed, and that is why sustained climate change seems to snowball with effects. For example, that has to affect certain bug hatches in some way, I assume, assist or hurt the sucker spawn? and other early spring events. Even if the rain comes in May, the damage has been done on some level. Freestone creeks got warmer faster this year and last, and even if they cooled off again, the disruption was a disruption and not the normal ebb and flow of rain events. Timing is everything with these odd fluctuations. Can the resident Bill Nyes weigh in?

Dear Nymph-wristed,

I agree, and this goes hand-in-hand with my post immediately above to troutbert.

Erasing the rainfall deficit in one day doesn't actually erase the deficit except from a statistical standpoint. Fifty years ago it seemed we used to get 2 or 3 days of steady rain, that added up to an inch or two. Most of that water had chance to get underground. Nowadays it seems to be feast or famine, and I can get a 2- or 3-inch deluge around my home while people 10 or more miles away see little or nothing.

Maybe part of my observations are based on the fact that I live at the foot of Blue Mountain and the mountain can affect precipitation locally. But it's no stretch to say that rainfall certainly seems to be much more scattered and sporadic than it was back in the day.

Regards,

Tim Murphy

 

[Mike]

Which streams have been dewatered, and what do you think is causing that?

Yes, when I read that I wondered “where is ‘around here?”’

 

[troutbert]

Yes, when I read that I wondered “where is ‘around here?”’

I'm not doubting that streams are being de-watered, i.e. their flows reduced. I'm just interested in learning what streams, what areas, and the causes.

 

[caddisflyer]

Which streams have been dewatered, and what do you think is causing that?

A lot of the streams in Lancaster County where I grew up. I know as a boy I had a small boat and could go up some of them without any problems. Now they are much lower and one is almost a trickle. I noticed it happened when they started developing the area with homes and businesses. In particular Brubaker Run and Little Conestoga. Those two I am most familiar with. If my memeory is correct many of the Furnace Hill streams like Seglock and Hammer etc seem much smaller overall. The dewatering of streams over by Carlisle is well known.
I would add Conowingo Cr. to that list also. That one is mainly in an agricultural area so no idea what happened there.