Recipe for Saucy Homegrown Algae

Serious algae outbreaks have hit more than 20 states this summer. Florida was the first to appear in the news, after nutrient-laden water from Lake Okeechobee flowed downriver into the ocean, smearing beaches and eastern estuaries with gooey green algae. Across Florida, the Miami Herald reports there have been more than 40 algae blooms this summer.

On the west coast, officials in California have posted danger signs at more than 30 lakes and reservoirs due to algae. In July, a 150 square-mile inland lake in Utah turned anti-freeze green when toxic blue-green algae spread across the lake, sickening more than 100 people.

03_Algae_onhand2Minnesota has had a couple of incidences of toxic algae this summer – two dogs died from swimming in Lake of the Woods and Mississippi River – but nothing quite as dramatic as the blooms that have closed beaches in Florida and Utah. Even so, there is plenty of grimy, green algae on most of our shallow lakes and bays right now and it’s not likely to go away until cooler weather returns this fall.

There are regional variations in the recipe for algae, but most include two key ingredients: 1) nutrients from farms, lawns, golf courses and business areas that run off into nearby wetlands, streams, lakes and rivers; and 2) warm water temperatures. In freshwater systems, phosphorus acts as a limiting nutrient for algae, meaning the algae will keep growing until they run out of phosphorus, whereas in saltwater systems, nitrogen is the limiting nutrient. Not all algae is toxic, however. Filamentous green algae, which is commonly found in lakes, is your stereotypical swamp monster type of algae – gooey, blobby, and greenish brown. It’s a recreational nuisance but not poisonous. Blue-green algae (cyanobacteria) usually looks like pea soup or spilled green paint in the water. Some strains are safe, but others can cause vomiting, diarrhea, headache and rashes.

Interested in whipping up a batch of blue-green algae for your next family gathering? Here’s what you’ll need:


  • 1 pound phosphorus (If you don’t have fertilizer, you can substitute grass clippings, soil or leaves. You can also use manure, dog poop, or failing septic systems, though it will obviously affect the flavor of your algae.)
  • Water (Rain is the best source of water, though you can also use snow melt.)


  1. Spread the fertilizer liberally on your farmland, turf or gardens. Allow loose pellets to roll off onto the sidewalk. If you are using grass clippings, blow them into street and leave them there for up to 1 week until it rains.
  2. Avoid sweeping up leaves, grass or spilled fertilizer before it rains. If you have bare soil, do not cover it with erosion control fabric, as this will prevent it from washing away.
  3. Watch it rain. (This is the easy part!) If you want to accelerate the process, you can irrigate your lawn with groundwater to create additional runoff.
  4. Ignore any pleas to think about future generations or people living downstream. This is your time and you don’t live downstream.
  5. After the nutrients wash into your local lake, wait while they steam for 2-3 months. As lake levels go down and the water heats up in the late summer, the nutrients will concentrate and algae will begin to grow exponentially.

This recipe will make up to 500 pounds of algae, which could last for as long as one month. Enjoy!