Re: [Paddlewise] Reading the water

Thank you, Craig,David , and all for the discussions of tidal motions in
rivers.  
It explains two phenomena of the Delaware River as well. One of our
favorite trips here is on Crosswicks Creek, which enters the Delaware River
a few miles below Trenton and about 80-90 miles above the meeting of
Delaware Bay and the Atlantic.  Nonetheless, there is usually at least a 6
ft tide range, sometimes over 8. --And it's fresh water; a really
extensiver marsh.  
	Typically we start about 2 hours before high tide time, paddle up to our
destination around 6 or so miles upstream, stop for lunch, wander around,
do some fishing, read a book, etc. until the tide turns and we ride it back
out.  Usually this is necessary because the tidal flow is often as great or
greater than how fast we can paddle.  Being that far up, we look to see how
the flotsam and jetsam is moving to decide when the water flow is once
again in our favor.  
	On many occasions we have noticed that the water level has begun to drop
although there is a healthy upstream flow still present.  We'd also noticed
that the return trip is always much faster.   Now we have some idea of why.
	So thanks!
	Trenton is considered the upper limit of tidal activity.  There's a long
gradual drop there, called Trenton Falls, which is higher than the tide
range, so from there above tidal activity is nonexistent.
	Or so I thought.  About 14 miles above Trenton is a whitewater paddling
site called the Lambertville Wing Dam.  It's a terrific place for practice,
and sometimes the only ww place in the area during the dry season.  Lots of
rocks, drops, eddies, etc. and it's easy to while away a whole summer's day
there.  I had noticed on some occasions that there was a very slight rise
and fall during the day of the water level, judging by the wet lines left
on rocks, that sort of thing.  
	The river is the main source of water for Philadelphia, and there is a
minimum flow requirement to keep the salt wedge from coming up from
Delaware Bay to the point where it gets into their system.  That's usually
done by releases from reservoirs in New York, and you can often see bursts
of water coming down the river reflected on the gages upstream.  So I
thought that that was what I was seeing.  --But something about that never
seemed right to me, and lo and behold, your explanations hold more water,
so to speak.  What I am seeing, I think, is a very small residual tidal
effect all the way up there...
	So thanks again!

Joe P.
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