The Problem with Phosphorus
Phosphorus like nitrogen, is an important nutrient element. Many important molecules within cells contain phosphorus atoms. For example, adenosine triphosphate (ATP) is a phosphorus-bearing compound. It occurs in every living cell where it plays a key role in energy storage. It's a potent fertilizer. Look at that bag of fertilizer at the garden shop - it has numbers like 10 - 5 - 10, representing the percentages of nitrogen, phosphate*, and potash in the mix. (The middle number is % of phosphate.)
So what's the problem? Maine lakes are well supplied with nitrogen and potassium, all that's missing is the phosphorus to promote vigorous growth. The trouble is, what grows is algae, that icky green stuff you sometimes see in the water. In a multi-step process, once phosphorus is introduced into a lake, it promotes the growth of algae. The algae then die and sink to the bottom, where they decompose. The decomposition process uses up lots of oxygen from the water. No oxygen = no fish, no animals of any kind, essentially a dead lake. The lake becomes "eutrophic," to use the $2 word, and that's the kiss of death for the lake. So, we need to keep the phosphorus out of the lake. Remember, Panther has a nominal "flushing rate" of about 1/year; in other words, anything you put in the lake stays in the lake for a long time.
Panther Pond Phosphorus Data 2018 - 2019
Date Depth ug/L
8/27/2018. 21 m 27.0
11/12/2018 20 m 11.7
10 m 32.9
6/10/2019 21 m 11.9
8/27/2019 20 m 22.9
10/25/.2019 20 m 83.5
There are concerning levels of phosphorus in Panther Pond. Ecologists generally agree that, on the average, a lake should not have over 15 ug/L. If it does, an algal bloom could result.**
How does phosphorus get into the lake?
* Phosphate - a phosphorus-based chemical compound used, e.g., to provide phosphorus in fertilizers.
**Investigating Aquatic Systems, Andrews, Prentice Hall 1987
Phosphorus like nitrogen, is an important nutrient element. Many important molecules within cells contain phosphorus atoms. For example, adenosine triphosphate (ATP) is a phosphorus-bearing compound. It occurs in every living cell where it plays a key role in energy storage. It's a potent fertilizer. Look at that bag of fertilizer at the garden shop - it has numbers like 10 - 5 - 10, representing the percentages of nitrogen, phosphate*, and potash in the mix. (The middle number is % of phosphate.)
So what's the problem? Maine lakes are well supplied with nitrogen and potassium, all that's missing is the phosphorus to promote vigorous growth. The trouble is, what grows is algae, that icky green stuff you sometimes see in the water. In a multi-step process, once phosphorus is introduced into a lake, it promotes the growth of algae. The algae then die and sink to the bottom, where they decompose. The decomposition process uses up lots of oxygen from the water. No oxygen = no fish, no animals of any kind, essentially a dead lake. The lake becomes "eutrophic," to use the $2 word, and that's the kiss of death for the lake. So, we need to keep the phosphorus out of the lake. Remember, Panther has a nominal "flushing rate" of about 1/year; in other words, anything you put in the lake stays in the lake for a long time.
Panther Pond Phosphorus Data 2018 - 2019
Date Depth ug/L
8/27/2018. 21 m 27.0
11/12/2018 20 m 11.7
10 m 32.9
6/10/2019 21 m 11.9
8/27/2019 20 m 22.9
10/25/.2019 20 m 83.5
There are concerning levels of phosphorus in Panther Pond. Ecologists generally agree that, on the average, a lake should not have over 15 ug/L. If it does, an algal bloom could result.**
How does phosphorus get into the lake?
- Soil erosion - When stormwater carries soil into the lake, it carries phosphorus into the water as well, because phosphorus clings to the soil particles. Hence the effort to prevent erosion around the lake. It's best if stormwater is filtered through the ground, with infiltration trenches; or diverted through vegetative buffers. Almost as bad as bare soil washing into the lake is water running across a lawn and directly into the lake. It's always preferable to have a zone of deep rooted native plants to filter the water before it gets to the lake. There is help available in the form of information and advice, and possibly even some funding, to control eroding areas. Please contact RWPA or PPA for evaluation and advice if you have bare bankings, driveways, or lawns where stormwater can reach the lake without filtering through a zone of woods or brush. (And it's not just a stormwater problem; boat wakes can also cause significant soil erosion, so please watch your wake when boating.)
- Fertilizer - Think twice about fertilizing your lawn, you probably don't need additional fertilizer for your lawn or garden. If your soil doesn't seem to be producing well, you could try a little lime first. A soil analysis would help to determine just how much fertilizer you actually need. Most Maine soils have adequate supplies of phosphorus. By law, retailers near lakes must carry zero-phosphorus fertilizer, so be sure to get that type if you must fertilize at all. (If you think a patchy lawn is ugly, wait till you see what your property value looks like after the lake dies!)
- Cleaning products - many detergents, soaps and shampoos are loaded with phosphorus (though that is beginning to change through the efforts of environmental activists.) There are some non-phosphorus products available, and you might give them a try. At least, make sure the cleaners all go through the septic system or the vegetative buffers, not straight into the lake. Don't wash your car, your boat, your dishes, your pet, or yourself where the runoff can reach the lake. Keep the soap and shampoo in the bathroom, not on the dock.
* Phosphate - a phosphorus-based chemical compound used, e.g., to provide phosphorus in fertilizers.
**Investigating Aquatic Systems, Andrews, Prentice Hall 1987
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