Algae...... The Good, The Bad and The Ugly. If you live on or near a lake, pond or any sort of body of water you have seen, smelled and felt algae
. It is a part of every water body in the world and believe it or not it is beneficial to have algae in the water - at least in proper quantities.
Just like your Mom used to say, "everything in moderation" the same goes for algae. You want the right amount in balance with nature, if you spray chemicals and kill ALL the algae, well the water might look cleaner, but it is actually sicker.. just not in an obvious way.
Algae is a living organism, some algae is actually bacteria - Blue Green Algae for example - This is a very dangerous type of algae if it gets out of control and is a neuro toxin to animals who might ingest it. Dogs, Cats and numerous other animals can suffer seizures, neurological effects even death from ingesting the blue green (cyano bacteria) from lakes and ponds. DO NOT GET THIS ON OR IN YOU - IT WILL MAKE YOU SICK. IT IS THE FRESH WATER RED TIDE. This is one important reason to clean your pond and maintain it just like your yard.
Other algae provide food for fish and other animals, generates oxygen through photosynthesis, algae can even act as a filter for certain nutrients and fertilizers. It all depends on type and quantity in your lake or pond.
For example, there is a large lake in Florida that on the surface is beautiful. It is crystal clear with no algae in site. You can see straight to the bottom and marvel at mother nature. What people don't know is that the lake does not support wildlife. The dissolved oxygen is below the levels to sustain life, at least for fish, because there isn't any photosynthesis going on during daylight hours. It is a relatively algae free water body for now, but if it can't support life the fishing is never any good.
On the other hand, there are some lakes or ponds full of algae, string algae, filamentous algae, blue-green algae and the dissolved oxygen is good. They look horrible, they smell and burp and are full of bugs and slimy creatures.......BUT there is lots of life, too much life, and nobody wants that either.
Why does this happen? Well, it would normally happen over time. Algae buildups and die offs the natural cycle of life changes lakes and ponds into bogs then swamps then...well... Florida. But that takes hundreds of years and just the right recipe. But humankind has once again interceded and helped nature to speed up the process by turning the majority of lakes and ponds into "drainage easements" or "storm water retention areas". So now the pond or lake is receiving 10, 20 or 30 times the natural runoff from rain which is loaded with street trash, sand, 
dirt, fertilizers, garbage, organic matter, inorganic matter, hydrocarbons, heavy metals, fecal waste, urine and a host of other things. Click here for the State of Florida's report on street sweepings and the effects on ponds and lakes.
If it is in the street it ends up in your lake or pond. Algae loves nutrients in any form. They gobble them up and multiple faster than a super computer. Nothing slows them down as long as the food is available. They grow and grow until they cannot be supported anymore and then usually rapidly die off, taking ALL the dissolved oxygen with them and the lake dies.
All of this "dead algae" sink to the bottom and rot. Very much like a compost bin the dead plant life rots, decomposes uses oxygen and produces hydrogen sulfide (rotten egg smell). After a while it just becomes food for the next algae population. This cycle continues for years until the lake or pond is dredged (dug out) or filled in.
Chemical spraying is just another way Mother Nature is sped up. It kills all that ugly plant and algae life, but guess what??? It all sinks to the bottom, rots, decomposes smells and becomes next years food.
By now, if you are still reading, are wondering.... What the heck can I do? I can't stop the rain, I shouldn't spray, I can't "filter" the incoming water... But we have to do something.!!
The answers are here in this web site, but it takes a plan, patience some politicking and organization.
First and foremost- EDUCATE YOUR NEIGHBORS as gently as possible to the use of fertilizers and pesticides. Teach them how whatever goes down the storm sewer ends up in your (or their) backyards, including runoff from washing cars, lawn maintenance, Fourth of July celebrations... 
ANYTHING!!.
Form a group of interested individuals to clean the lake and be responsible for some basic maintenance This is a thankless job that will cause you reconsider your place in the world and make you regret that you ever read this web site, but in actuality if you can organize and keep things friendly you end up with more friends, getting to know your neighbors and doing something good for nature and your property values.
Educate this group with the help of some educational resources. Here in Florida LAKE WATCH is through the University of Florida - Go Gators! - it is free and they train you how test the water. They even give you the test kits.
Next plan on spending some time pulling out algae. Yes you have to touch it and haul it in. Different algae takes different kinds of "rakes" you can contact us HERE for easy to "build it yourself" 
rakes and nets for this reason. Don't hesitate to pull out those obnoxious weeds and lilly's either. Leave native plants in, unless they are over-running the lake since they absorb and process many nutrients and provide habitat for fish and birds.
It seems like a daunting task. But with a little elbow grease and some solid reliable helpers you can do it. For example, Lake Sylvia in Seminole, Florida was loaded with string algae. Click here for pictures and click here for information. There are 37 homes around the 3.5 acre lake, each home has between 25' to 100' or lake front per house. Every home had string algae 4' deep and 20 feet wide around the entire lake.
Eco Pond Rescue, a two man lake maintenance company and lake residents, "raked" one yard a day. It took anywhere from 30 minutes to 2 hours depending on the size of the property. Within two months 370 50 gallon trash bags full of "dried" string algae were removed from Lake Sylvia. Two guys, working a couple hours each day cleaned the majority of a 3 acre lake. Neighbors helped when they could but the lions share of the work was done by Eco Pond Rescue. If two guys can do it in two months, imagine if you had six willing volunteers.
Algae removal is cheap, relatively easy with the right tools and offers a great benefit to the water body. It takes out decaying or rotting materials, removes nutrients and waste and gives the water body a chance to recover. Its better than spraying chemicals and the results will surprise you.
Good Luck!!!
