Tailwaters: how long to clear after a rain?

[Six-Gun]

I'm curious as to how long it usually takes for an area directly under a large dam to clear up after a rain storm. I'm talking literally inside of an 1/8 mile from the base of the dam wall. Can I reasonably expect that it won't be blown out the morning after the rain, which should be over about 6PM the night prior? Thanks for any help you can give.

 

[Dcap240]

It depends. I know on the lehigh it depends on how much rain fell and how high the water levels are prior to and during the rain. For example if the lower lehigh or even the delaware is high enough they hold water back sometimes for 2 days before they release it. But it also depends on the level of the lake. I remember a time a few years ago where everything was at or above flood stage and the lehigh was held back to a trickle for 2 or 3 days. It also depends on the dam itself the FEW was built for flood control. If we are in a drought they may not release much water at all, if everything is flooded it may be unfishable for a few days.

 

[Six-Gun]

Excellent info and thanks for that very critical piece about them potentially holding water back. I will call the corps of Engineers and hopefully find out what their plan is for the post-rain release.

 

[streamerguy]

Yeah, it can depend on the size of the reservoir, the size of the river/stream(s) feeding it(ie. how much muddy water is flowing into the lake), etc.

I fished(or attempted to) two local tailwaters in early March. The levels were great.......but the water was extremely muddy even directly below the dam.

I've fished the same two tailwaters when they were over their banks, but the water was relatively clear.

 

[LetortAngler]

Tailwaters like the Yough, Savage have a USGS gauge that's very helpful and are pretty good indicators. I always check before heading out cause even with a few days of no rain the Yough can still be very high below confluence.

 

[streamerguy]

My home tailwater has been very high for close to a month.

And yep always check the gauges(if available) like LetortAngler said

 

[Six-Gun]

For full disclosure, the tailwater I'm hitting is actually the Whitewater river in Brookville, Indiana. It is a pretty large reservoir and does, in fact, have a gauge below the dam. I will definitely be checking it the morning of the trip. The only catch is that it's looking like a 60% chance of rain for the 3 days preceding the outing. I'm bringing a new guy along and don't want to drive 1.5 hours for a trip that's a bust before it starts. I had good luck on this river my last time out, but the conditions were also much more predictable and ideal leading up to it.

 

[krayfish2]

What it comes down go is experience on that specific tailwater . You have to know the impoundment, understand the use of the lake (recreation or flood control),.what flow is safely waded and how cfs released and lake level affect turdidity. Just when you think you understand it, they'll dump 5x the normal release for no apparent reason.

If you haven't logged a ton of time on that river, I'd make sure to contact a shop or look for a blog / fishing report on that specific watershed. Even after rains, many tailwaters remain low and clear.....at least to the first feeder enters. You'll slowly learn how gauge height, cubic feet per second release, weather conditions and lake level impact clarity / fishability.

 

[SBecker]

In regards to the Lehigh, they might be holding water back right after a major storm and the gauges below the dam might be showing a trickle, but you have 20 feeders below the dam spewing a mudslide into the Lehigh. Then when those clear up and things seem to be getting back to normal here comes FEW and the ACoE blowing it out. It is a wonderful thing.

I can't wait till this May with no fishing releases and all whitewater releases. #censor# is going to be epic.....lly awesome for rafters!

 

[Six-Gun]

Very good footnote about the feeder stream affecting the overall water clarity. Thankfully, the stretch I'm looking at doesn't have any feeder streams for the first two miles, so as long as they keep the water held back, the condition of the water should be whatever it is near the base, or close to it, for that entire stretch.

 

[SBecker]

Yep, the Pohopoco is the same way. I always fish it when everything else is blown.

 

[dryflyguy]

Tailwater sections of streams have saved many fishing trips for me after heavy rains. While all of the other streams in the other were muddy, the area immediately below a bottom release dam can stay clear.
This has happened for me many times on the yough, east branch clarion, and delaware rivers

 

[pcray1231]

I'm curious as to how long it usually takes for an area directly under a large dam to clear up after a rain storm. I'm talking literally inside of an 1/8 mile from the base of the dam wall. Can I reasonably expect that it won't be blown out the morning after the rain, which should be over about 6PM the night prior? Thanks for any help you can give.

It depends on the dam. But usually, tailwaters are low and clear when everything else is high and muddy. And vice versa.

They are flood control dams. When most streams are high after a rain, they hold back to keep the downstream rivers from flooding. But when other streams finally drop, that's when they get rid of that water to get the lake level back down, and prepare it for the next rain.

If a very large, or lengthy rain event is well forecasted, in addition to the above, they may actually blow it out before the rain even starts. Just gives them more storage space in the lake, and thus allows them to really hold back when other area streams are raging.

 

[Chaz]

It depends on the flow regime how they clear and probably the size of the reservoir or it's depth.