Cheap Depth Sensor Needed

Depends on the stream. If you mean as in a creek or river type stream then a simple measuring stick or rod has for centuries done quite well.

You beat me to it...

The rope with a lump of lead work well too. Try swinging the lead.

How about using the back-pressure in an air tube fixed so that the outlet of the tube is at the bottom of the stream? The back-pressure in the tube is related to the depth of water above the outlet. Simple. Such a device is affectionately known as a 'bubbler level gauge'. It can be as cheap as chips, as most of the materials can be scrounged.

When I go fishing I just use a heavy weight at the end of the line and adjust the float so that I can still see it when the weight is at the bottom....

John.

Of course its also possible to get a good idea by noting how far the end of the rod dips down until the weight hits the bottom.

It all depends on the accuracy required?

John.

fathom - measure the depth of (a body of water) with a sounding line.

With a weight on a line, lower the line slowly over the side of the boat until it touches bottom. Note the waterline. Retrieve the the line and starting at the noted waterline, stretch the line from fingertip to fingertip. Count the number of times (fathoms) the line can be stretched until you get to the weight. This will quickly give you the general depth in fathoms.

1 Fathom ~= 6 feet or 1.8 meters.

For electronic systems see

http://www.nextag.com/depth-sounder/search-html

I have a stream to cross on the way to my property, it's about 75' wide and flows fairly fast. If there are many small waves, like mini washboards on a dirt road, it's a foot or less deep and safe to cross. If the water has larger waves ,it's time to take a nap and wait for it to go down. Back in day,old timers always carried some old boot's to put on, and wade out and measure the depth directly. Flip-flops=1",tennis shoes=2",high tops=4", cowboy boots=1', rubber boots=2', waders=3',snorkel=5'+.

In a recent post you wanted to know flow-rate, and here you want to know depth. Don't interpret my comment as rudeness, but you have little chance of finding an answer with the information you have given. Describe more about the situation and difficulty you have. There is an abbreviation, GIGO, that means 'garbage in, garbage out'. From the information given, you may as well wade into the stream with a bucket. Providing more detail will most likely prompt people to offer helpful suggestions. Good luck to you Zakirmohd.