MUD

[Oregon Native]

This came up today between me and an older gentleman. He says when you have muddy water on a reservoir that it’s only on the surface. It doesn’t go all the way down. He says studies prove it. I disagree. Especially now with all this rain. 

Experts please step forward 

thanks

[CroakHunter]

Dirt, debris, and other particles are more dense than water. Ions that are more dense than the solution they are in, sink. I say its muddy all the way through. The only place I would say that it isn't muddy all the way through is if you have dirty water dumping into clean water. The inflow of the dirty water would keep it higher in the water column for a bit before it got the chance to slow its movement and begin settling in the bottom.  

[Team9nine]

A lot of factors involved including wind, current and time of year (water temperature). A sudden warm inflow will often float on top of colder denser water for a time. Also works in reverse, especially as settling occurs, which is almost always from the top down and the bank in. Type of particulate will play into it also, with larger particles settling out or down quickly, while lighter tinier particles like clay may stay suspended for awhile. The farther you go down lake or down creek toward the dam, the less likely you are to have heavy mixing (e.g., a stain instead of mud). I would say the more consistent the water temperature throughout the water column, and the longer it has been since the influx, the more likely the "mud" is through the entire water column to some degree.  

[Bluebasser86]

I have seen water that was only muddy near the surface but that's usually with heavy runoff. 

[Oregon Native]

Thank you….some of these thoughts I mentioned and it's nice to not be the only one who thinks this way.  We are going to drop an Aqua view down and see....with the infer red we may be able to settle this story.

Thanks againb

[DScott87]

I had to sign in just to reply to this. I am a certified scuba diver. I can tell you that thermoclines exist and they can separate muddy/stained water from clear. The first time I ever experienced this was in a quarry and I will never forget it. The water was so muddy, I couldn’t see my hand in my face. As I kept descending, I could feel an extreme temperature change in the water. It went from warm to 60 degrees and out of nowhere you could see straight to the bottom, 100 feet down. It was unbelievable. 

 

That being said, I am sure they are numerous factors in play that will affect this. 

[MN Fisher]

2 hours ago, DScott87 said:

I had to sign in just to reply to this. I am a certified scuba diver. I can tell you that thermoclines exist and they can separate muddy/stained water from clear.

Having been certified SCUBA since 1977, I can attest that everything you say is true.

[Oregon Native]

3 hours ago, DScott87 said:

I had to sign in just to reply to this. I am a certified scuba diver. I can tell you that thermoclines exist and they can separate muddy/stained water from clear. The first time I ever experienced this was in a quarry and I will never forget it. The water was so muddy, I couldn’t see my hand in my face. As I kept descending, I could feel an extreme temperature change in the water. It went from warm to 60 degrees and out of nowhere you could see straight to the bottom, 100 feet down. It was unbelievable. 

 

That being said, I am sure they are numerous factors in play that will affect this. 

Wow.....thank you much

[lo n slo]

retired NC Driking Water Treatment guy here. everyone is right! the stratification aspect does play a very important role, but the water isn’t always stratified, especially this particular time of year in many reservoirs. in fact, late winter/early spring always gave us fits. cold, dense, muddy (turbid) source water is very difficult to treat (floc out). most raw water reservoir intakes are designed with the ability to “draw” water from two, or more, depths, in order to minimize the effects of various raw water quality issues brought on by summer stratification and fall turnover. but the cold and muddy water in late winter/early spring always seemed to find it’s way into the intake no matter what depth we drew from. it was unavoidable. riverine systems will obviously be more prone to a thorough “mixing” too. 

[soflabasser]

I have +20 years experience in freediving both freshwater and saltwater bodies of water and agree with the scuba divers above about thermoclines. These thermoclines often have colder, clearer water on the bottom and murkier, warmer water on the top. 

4 hours ago, MN Fisher said:

Having been certified SCUBA since 1977

What is one of your favorite dives that you have done?

[MN Fisher]

2 hours ago, lo n slo said:

in fact, late winter/early spring always gave us fits.

At least in northern states, that's because of the 'spring turnover'.

 

The fall one is well known...surface water cools to it's maximum density of 39-degrees and rapidly sinks, causing an upwelling from the bottom.

 

In the spring, the cold water at the surface warms back up to 39-degrees and sinks through the middle layer to mix with the other 39-degree water already at the bottom...this causes an upwelling as well, but not as severe as the fall one.

 

Things I remember from my limnology classes 40 years ago.

2 minutes ago, soflabasser said:

What is one of your favorite dives that you have done?

Diving some of the wrecks around Isle Royale, Lake Superior.

[soflabasser]

7 minutes ago, MN Fisher said:

Diving some of the wrecks around Isle Royale, Lake Superior.

Saw some pictures of the placed you dived in, it has very clear water for freshwater. Not sure which is my favorite dive, I have many. There are a couple reefs in the keys which are absolutely gorgeous with extremely clear water, corals, and thousands of fish all around me when I dive there. Also like diving freshwater springs in Central/ Northern Florida.