Pond Boss Forums GENERAL QUESTIONS Water chemistry Got my water sample results... Now what ?

I have a (soon to be) 1.5 acre pond that is about half full right now & waiting for more rainfall to fill. In the meantime, I took a water sample and sent it to LSU for analysis. What they found is below:



Although my water level still has about 5' more to rise (to give me about 6' in the shallow end to 11' in the deep end, with a 1' shelf about 10' wide along the entire perimeter), which of these levels do I need to monitor and/or adjust ? And how do I adjust those parameters that need it ?

Thanks very much.

i assume you told the lab this was for a pond water test, so i'll ask the question......what are the terms "very low, low, optimum, high, and very high" relative to? is there some kind of standard for pondwater, or are these relative to average inland surface fresh water bodies?

i'm sure the Xperts will be able to provide you input on the actual results.

Thanks for posting that report and scale.

Did you have the pond soil tested ?

Water usually over time reflects the soil content but it can be different based on the watershed and runoff. More so in a new pond. Is this a excavated pond or does it have a dam? Was lime added during construction? What are you pond goals ( fishing , swimming , etc)?

Assuming you soil and water are similar you could use a little agg. lime to get the alkalinity up although it is now above the min. level of 20ppm.

Nos. 1 , 2, 4 and ph are all related to the pond water being slightly acid even though the ph does not currently reflect that. It is not unusual in water tests for the ph to not be reflective of the overall situation because ph changes widely through the day. Adding agg. lime will offset their low numbers for a period of time 2-5 years. Alkalinity is a good thing to monitor. Here are 2 links to understanding water quality.

http://aquanic.org/publicat/state/il-in/as-503.htm

http://srac.tamu.edu/index.cfm?catid=25 list

http://srac.tamu.edu/tmppdfs/13452410-46...253473991c37951

DIED I am fairly sure those scales are for ponds/fish based on the ranges given. I have not seen tham set out that way before. Does anyone know what SAR is ?

Yes, there was a place on the form to check whether the water was 1) Well 2)Pond or 3) River or Spring. So I checked "Pond". Also has to check either 1) Agriculture or 2) Aquaculture, so I checked "Aquaculture"

I know that pH, Alkalinity, Hardness & Nitrates are some of the important ones, but for example my Alkalinity was 34.16, which I thought would be OK, except their report says that it is low...

Am also looking at the Manganese and Iron, which are very high and high, respectively - don't know if this would be a problem, or how to fit it if it is...

Thanks for the links, I will read up some more on water quality. I did send in a soil sample at the same time. Here are those results:


I hoped to get some agricultural lime spread onto the banks at a rate of 2T/ac, but it appears that the spreader will not be able to do it b/c he cannot backup to the pond edge in all the places required to distribute the lime. I may just wait until the lake is full and then treat the water...

Folks this is a very good learning example to take note of the results.

Compare the results of the water test ph (7.07 excellent) and the soil test ph [water](5.22 very low/acid). The recommendation add 2 tons of lime per acre even though the water test ph looks good.

Chatlanha you did a very good job getting both tests done. Are you using any well water yours or local system (higher metal contents)? You treat the dirt with lime not the water as the water takes up the dirt's character. You can use bagged pelletized lime (not hydrated lime) if the truck can't get there. Just spread it around the pond bottom/banks on the dirt or in the water.

The only source of water is surface runoff from a 30 acre residential subdivision (all either roofs, streets, or grass lawns) which pours into the lake via a 36" outfall pipe when we get rain. I was hoping to get an agricultural supplier to spread the lime on the remaining dry banks before we get more rainfall, because the bulk rate for lime is so much cheaper than what I can get in bags. But his equipment spreads the lime behind and on both sides of his truck as he drives along the spread path, which won't work in my case.

Would I use less of the pelletized lime ? 'Cause if I have to spread bags by hand, there is no way I can spread that much by myself...

great job on having both the soil and water data for comparison. not sure what SAR stands for.

could you have the lime dumped and hire a local guy w/ a 4wd kubota or backhoe?

i hope the residential subdivision is on piped sewer.....if not, and they all have septics, you might want to monitor bacteria levels (e coli, strep, etc.) particularly if you'll be swimming in it.

edited post.....these kinds of things drive me crazy.........oh oh.....i feel an "ewest" post coming on........

SAR
SAR is the sodium adsorption ratio, which indicates a possible sodium hazard. It relates the amount of sodium relative to calcium and magnesium in water.

When the SAR is >3, the water is sodic, and can increase the exchangeable sodium percentage (ESP) of the soil.

When the ESP of a soil is >6%, the soil is likely to disperse and adversely affect soil structure, causing reduced infiltration, percolation and drainage, cloddy seedbeds and poor seedling emergence if crusting and sealing of the surface soil occurs.

The adverse impact of sodicity in water is related to its salinity. There is a risk of both reduced infiltration and declining soil structure if the water has moderate to high SAR but low ECw. There will be no reduction in the rate of infiltration of water with moderate to high ECw, regardless of whether the SAR is high or low, but the sodicity hazard remains.

The main danger is when soil sodicity increases due to using sodic water, and the soil disperses in a wet year or when fresh channel water is used.

The summary guidelines for interpreting water SAR values are:

<3 : no problems as the water is non sodic
3 to 6 : minor effect on clayey soils if ECw is <1.5
>6 : has increasing effect on all soils at low to moderate salinity (up to 2.5 dS/m) and starts to reduce growth of most crop and pasture plants
>9 : severe risk of increasing soil sodicity on most soils
If SAR is >6, refer to the table in the Agfact Using saline water for irrigation for salinity tolerance levels and seek advice from NSW Agriculture.

taken from the following link:

discussion of SAR

The drainage system is a stormwater sewer system. That is, only stormwater (rainfall runoff) enters these pipes. Sanitary sewer is collected by another piping system entirely. Thanks everyone for the help and the links. I will check with the agricultural guy to see if he can bump some piles that I can get someone else to spread...

chatlanha

Ask if the ag supply truck can "block" one side of the spreader on the back of the truck thereby throwing the lime only toward the pond side. My ag supplier has one truck that can do that but most in his fleet do not. I just make sure he knows that I want that truck.

If you cannot get the truck all the way around your pond another option would have the truck parked in a few locations and just let out a large amount of lime.

If you wait for the pond to fill another option is a lime barge that basically is a pontoon boat on which lime is shoveled and then using gas powered pump washed off the barge into the water. You can get great coverage and distribution.

Frank

DIED thanks I did not know what SAR was. The chart above is the first time I have seen it. It is very low in this pond which sounds good as per your findings. I learn stuff here all the time.

DIED, thanks. I have read that 3 times now and will have to dig in some more.

Well we had 1 or 2 inches of rain last night. Multiplied by a 30 acre drainage area & you get about a 2.5 feet increase in my water level - I'm still not sure as the sun hasn't come up yet. I am really glad to see more water in the lake, but it makes liming what's left of the banks less practical than before. I think that I will wait until the water reaches the elevation of the overflow weir and then treat the water. Thanks again to everyone for sharing such a broad base of knowledge !

DD1 and ewest, i hope it was helpful although that particular discussion is from an irrigation perspective, so read between lines for pond application.

So true about the water picking up the soil parameters. After the big rain (which maybe added 1.5-2 acre-feet) I rechecked the pH with my cheap aquarium strip. Although I tested near the water's edge where the water was in close contact with the soil, the pH was 6.2 now, as opposed to the sample that I sent to LSU, which was 7.07. I am thinking about adding some more hydrated lime slurry to bring up the pH a bit until we get the next big rain. After my pH is OK and stable, then I will attempt to add an alum/lime mix to get rid of the cloudiness without dropping the pH. Found a link for the concoction here

P.S. Merry Christmas everyone & thanks for helping!

I thought I would add to his post from my experience in this field.
Accurate pH can only be checked at sampling time. even in tightly sealed containers, there may be some pH change in transit. This is particularly true in low buffered waters(low alkalinity and conductivity waters). CO2 from the air can be absorbed and lower pH, and CO2 can be lost to the air raising pH. I would trust the reading you took at sampling over the reading from the LSU testing on such low buffered water.
When analyzing the water results, you need to know if the results are reported as ion or as CaCO3 equivalents. Most water samples are reported as calcium carbonate; i.e. calcium 40 ppm as CaCO3. The same goes for alkalinity. This is done to get everything reported in the same terms for ionic balance. If this report is as CaCO3 equivalent, you have extremely low calcium hardness and alkalinity. If as ion, then not so much.
I agree that adding lime seems to be in order.