Water draining into a hole in the garden

Our gutters direct water into a 4" pipe that goes about 20 feet away from the house through the garden. I created a little creek bed at the exit site with rocks and hoped to eventually have a pond with all the runoff. A few weeks ago, I noticed that about 6 feet below where the pipe ends, the creek ends in the water going down a small hole, about 2 1/2" diameter. We have had an incredible amount of rain (normal for where we are at the edge of the Gifford Pinchot Rain Forest, literally filling 55 gallon drums overnight that are just catching runoff from a small shed}.  I stood there this morning and watched dozens of gallons of water go into this hole with no sign of overflowing. I cannot figure out where the water could be going. The soil is clay and rock and does not drain that quickly. My first thought is that I should redirect the water. Wondering if I should have any other concerns?

Even if the water was running over sand based on what you said it should still be flowing a bit further.
So I worry that said hole will get bigger and one day swallow your home.
Maybe you have a "cave" under that layer of clay?
It could be a buried gas/oil tank that has rotted out or a oil septic tank or something.

maybe a mole tunnel?

Can you do a little exploratory digging there?

Mmm bit of a puzzle indeed ! How about putting a stick down the hole and seeing how far you get, more than a foot and I would be concerned and feel time to get some professional help on the ground . Any chance of a picture ? Take care

David

What S Bengi is describing is a "sink hole" ...

I wonder if the water happened to find two or three rocks that just happen to come together to form a place for the water to flow into.  Maybe the rocks are causing a suction because there is an air pocket underneath them.

You may want to consider diverting that water so it no longer goes down that hole. If you're watching dozens of gallons disappear, there's no telling what's going on underground. What I think unfortunately is happening, with that rate of water flow, is subterranean erosion, and there's no good way of knowing where that erosion is happening and how far in what direction. :(

Thank you all for replying. The reason I asked here is I hadn't really given it much thought until yesterday when I stood for several minutes watching it and started thinking about sinkholes and looked up pictures of them-yikes!
I then thought well, maybe it's not such a big deal and I'm being paranoid.
Of course I'm hoping it's not a big deal but we will certainly treat it as such. Today will see us diverting the flow and slowing it down-water is life but can also be so destructive. We are dealing with erosion in several  places since we live on the side of a gorge with 80+" of rain annually and most of that Oct-Apr.
Thanks again, I'll attach a couple pics just for reference.  

Two more

Judith Browning wrote:maybe a mole tunnel?

Can you do a little exploratory digging there?

That's what I thought it was at first, or snake, and it could be, but might have started eroding underground too.  I'll probably do a little exploratory digging since I'm so curious.

Is the hole on top of a hill or rise? Just thinking about a critter making a tunnel that say ran for 20 or so feet and then came back to the surface downhill from the top one. Potentially water could flow down the tunnel and then come out some where else that way. If the other opening was covered with grass you might not notice the flow.

I have clay soils with gopher holes and I once stuck a hose in one of the holes and ran it for 5 min at a good rate with no overflow. Turned out the water was just leaving through another exit I did not know about. Most critter tunnels have more than  one exit.

Daron Williams wrote:Is the hole on top of a hill or rise? Just thinking about a critter making a tunnel that say ran for 20 or so feet and then came back to the surface downhill from the top one. Potentially water could flow down the tunnel and then come out some where else that way. If the other opening was covered with grass you might not notice the flow.

I have clay soils with gopher holes and I once stuck a hose in one of the holes and ran it for 5 min at a good rate with no overflow. Turned out the water was just leaving through another exit I did not know about. Most critter tunnels have more than  one exit.

I agree, it likely started out as a critter hole this summer when all was dry but then the rain started and the hole is right next to my hand made stream. There very well could be another exit downhill under a huge blackberry patch. The hole isn't on a rise but our property is definitely sloped and there are the blackberries below it which would probably make for an excellent escape route for any creature.
Water has now been diverted away from the hole and we made sure it dispersed over a larger area at the end point.  Bonus: blackberry patch now has a path through it. 😁

could you maybe dye the water a bright color or put a handful of something that would float. and then look around to see if you can find and exit?

Ooh! A mystery, and possibly adventure! Of course, the adventure part would likely be messy and expensive, so let's hope you've avoided that path.

With that volume of water, I would expect an exit, or some open area underground, allowing for collection and a slower infiltration into the aquifer.

You also mentioned that you're on the edge of a gorge. How was it formed? Are there perhaps fissures in the bedrock that allow for such rapid drainage?

I almost want to take one of those plumbers' cameras on the end of a snake and shoot it down there, just to see what can be seen.

Any update on the potential sinkhole/sliding off into the gorge situation?

-CK

See if you can find a smoke bomb that will fit down a hole. Fire it up and plug the hole. See where else it comes out

Chris Kott wrote:Ooh! A mystery, and possibly adventure! Of course, the adventure part would likely be messy and expensive, so let's hope you've avoided that path.

With that volume of water, I would expect an exit, or some open area underground, allowing for collection and a slower infiltration into the aquifer.

You also mentioned that you're on the edge of a gorge. How was it formed? Are there perhaps fissures in the bedrock that allow for such rapid drainage?

I almost want to take one of those plumbers' cameras on the end of a snake and shoot it down there, just to see what can be seen.

Any update on the potential sinkhole/sliding off into the gorge situation?

-CK

Nothing to report, which is good of course! We just redirected the water and filled the hole, hoping for the best and haven't seen anything concerning. A camera would've been interesting-I was so fascinated with the well report. It is 800 feet deep, so went through many different layers/materials.
We live in the Columbia Gorge, so our property is not really any worse than anybody else's here but it's definitely a slide area. To get our building permit we had to have an updated geological report and while there are several slides a few miles from us, our neighborhood is supposedly in lesser imminent danger.
If a big earthquake hits, we'd likely be pretty screwed but I don't worry too much since worrying about that kind of thing never helps. We just try and be prepared for any disaster as best we can.
There are probably fissures and all kinds of underground caves and such.
Our property is mostly a few inches of clay sitting on top of rock with little pockets of nice dark soil where plant matter has accumulated.
If I ever see another hole like that, I'll be very tempted to get a plumber's camera!
The ideas of colored water and smoke bomb are also super ideas! Thanks you guys!

Sally Munoz wrote:

That's what I thought it was at first, or snake, ......

A plumber's camera would go down that hole and after several thousands of miles come up in the Kremlin!  First, it was elections hacking....Now, the Kremlin is stealing our water!  And always in the most uncanny ways!..... :-)

We don't have the porous soils of the PNW, but even the clay here in the Red River Valley, once dry enough, will produce some sizable fissures.  It gets bad enough that one must really be noticing when watering the garden so as not to lose all of the water being applied down one of those cracks.  But one good rain just seals them all up again.