Nitrate Levels And Your Pond – One Example From Iowa

As an Amazon Associate we earn from qualifying purchases.

7 5 11 flooded field

Whenever we talk about pond algae and pond algae control, there are a few things we almost always focus on.  One of those things is nutrients that feed the plant growth.  Of course, these same nutrients feed other plants too, but by and large, it’s the free-floating plants that get the most of it.  This includes algae of course, but also duckweed and watermeal too.

Interestingly, a recent MSN article out of Iowa discussed a current, state-wide situation there where one of these types of nutrients, nitrates to be precise, is affecting the drinking water in the state.  I’ll include a link at the bottom of this article to that one so you can look it over.

In a nutshell, it provides an interesting example of the way weather can affect our ponds and waterways, and how some of the things we do around these aquatic environments affect them as well.  

Weather And Your Pond

You might recall that about 12 months ago, in the spring and summer of 2012, we experienced a pretty deep drought through much of the country and here in the upper midwest it was no exception.  Underground wells were running dry or had to be drilled deeper by mid-summer, just to keep some drinking water available.

Ponds were very affected too and not in a positive way.  While they may not have run dry, there were a lot of fish losses due to low oxygen levels in the water.  We’ve talked a lot about this recently but as the water warms up (particularly above 78 degrees f.) it can’t retain as much dissolved oxygen.  Once this drops low enough, fish start to suffer and die.  And pond aeration is about the only thing that can guard against that kind of thing.

But in Iowa and in other states around us, the drought did more than just dry things up.  You see it’s very common for corn farmers to fertilize their fields to produce better growth and higher yields.  In a normal  year, with some average rains, this nitrogen based fertilizer would get into the plants where it was intended, but not last year.  It just stayed in the soil since most crops dried up or were stunted anyway due to the dry conditions.

This year, things have changed dramatically.  We’re over the average amount of rainfall as I write this in early June, and have had flooding in our local area twice already.  It’s been an uncommonly wet spring.

And herein lies the problem.

All those nitrates that were supposed to feed the crops last year are now washing into streams and rivers and a lot of the drinking water pulled from these sources is showing record high levels of nitrates in it.  As noted in the article, the Environmental Protection Agency requires nitrate in drinking water be kept at less than 10 milligrams per liter.

Above that level can be deadly to infants younger than 6 months because the chemical can reduce the amount of oxygen carried in their blood. Pregnant women are advised not to drink water above the EPA limit, as well as adults with reduced stomach acidity. Scientists have collected conflicting evidence regarding whether nitrate or nitrites are associated with cancer in adults and older children, the EPA said.

So obviously high nitrates in drinking water are a major concern and municipal water providers do have ways of either filtering nitrates out or lessening their concentrations.

For a pond owner however, dealing with nitrates isn’t quite as easy, particularly if they are high.  For pond water, the main thing to remember is this is a plant feeding nutrient.  It’s naturally part of what’s called the nitrogen cycle that occurs in ponds where ammonia (from things like fish waste) is converted into nitrites and finally into nitrates, which plants can consume.

Some nitrates are beneficial and even necessary to help aquatic plants grow, but too many will foster unwanted algae growth.  

How To Deal With Nitrates In Your Pond

So despite this problem, and the fickle weather that we all have to deal with from time to time, what can a pond owner do to deal with this issue?

We’ll it’s pretty simple and straightforward for the most part.

First, as the article notes, farmers put a lot of fertilizer on the fields which ended up simply running off into the water.  Ideally you’ll want to cut down and manage this issue of fertilization of your yard or grounds and keep that in mind…anything you put down will likely end up in a pond if conditions are right so know that before you apply it.

If you have livestock or other “nutrient sources” around probably the best thing you can do is build a buffer strip around pond to keep some of the runoff from going in there.  It won’t help in source streams and the like but any limiting effect may be helpful.

For small pond owners, it’s possible that source water could be nutrient rich, but by far the biggest influence on a small pond will be fish loading.  Keep your fish numbers at reasonable levels and remember the more they multiply and the bigger they get, the more they’ll influence the water quality in the pond.

If you can, be sure to use beneficial bacteria regularly which will help to lock up or use up some of these nutrients that feed algae directly.  Normally when you use good bacteria in combination with some desirable plants, you can make some good headway on algae issues. 

As our Iowa governor has noted, eventually things around here will return to normal and the nitrates will go down in our drinking water.  Often the same could be said of many ponds.  The weather may occasionally throw something into the mix that will upset the balance in the water, but if a pond has been pretty clean and stable for the most part before hand, it’s often only a matter of time before things clear up again.  Therefore I’d normally suggest not trying to quick fix the problem with a chemical treatment or something that will end up simply setting the pond back and disturbing some of the balance that you may have had to start with.

If you’d like to read more about the issue of nitrates in drinking water be sure to visit the link below for more information.

Photo courtesy of

Amazon and the Amazon logo are trademarks of, Inc, or its affiliates.