How much food and income can an urban farm produce?

I’m constantly on the lookout for how to seed the growth of local production — food, energy, water, products.  One good way to seed production is to start a new business that works within the current economic environment.  The choice of whether it is a commercial, a non-profit, or a co-operative business is really based on the type of community you are building.

I suspect many of you are also looking for ways for seeding production through business creation too, since it’s a good way to launch a community resilience effort that can move forward under its own power.  Here’s a handy rule of thumb:  The more people in your community that are able to make a living through the local production of essentials, the faster your community becomes resilient.

Today’s example (I have a couple of others in the queue for future posts) is Sweet Water Organics located in Milwaukee, Wisconsin.  It’s a small farm that has navigated the dangerous waters of the food business to produce food in downtown Milwaukee.  It’s not perfect, but we can learn something from it.

What makes Sweet Water interesting?  

First off, it uses a method of agriculture called aquaponics.  I’ll dive into the ins and outs of this method of intensive farming and home based food production in future letters, but for today’s purposes, it’s a combination of fish farming (aquaculture) and hydroponic farming (plants grown without soil in a bath of nutrients).  The used fish water is converted into a nutrient bath for growing plants hydroponically.

This is an aquaponics system at Growing Power, an urban mini-farm also in Milwaukee. The system seen here serves as the model for Sweet Water's commercial operation.

Secondly, Sweet Water is a commercially focused farming operation.  It produces products that sell into the local marketplace.  Typically, they sell direct to commercial restaurants, catering businesses, and green grocers that want fresh, high quality produce.  These products include:

  1. Fresh Fish.  Perch, Blue Gill, and Tilapia.  The focus is on perch and blue gill since they are the highest value products.
  2. Fresh Herbs and lettuce greens. These are premium products in the greatest demand locally.

How much food and how much is it worth?

Sweet Water’s three tier aquaponics system is located in a converted crane factory, which allowed Sweet Water to pick up some grant money for the conversion.  It is on track to produce (all of the below are estimates based on my research):

  • ~10,000 pounds of fish (mostly Perch) a month in 10,000 gallon tanks.  Each tank holds 10,000 or so fish.  Estimated costs of production are ~$2.00 a pound with nearly half of that being the cost of fingerlings to stock the tanks and the rest feed.  Given local access to end use markets, prices paid are about $5-6 a pound (round, uncut, fresh) leaving a net of ~$3-4 per pound.
  • ~2000 pounds of leafy greens, lettuce to basil, a month.  Greens prices vary.  ~$3 or so per pound, for picked that morning greens sold in bulk to local restaurants is likely in the range.
  • I suspect there is a considerable opportunity to move a bit upmarket with the product into fish processing (to filet) and a local kitchen.

So, the entire operation could generate up to $46,000 a month.  This is net the costs of raising the fish, but not energy and labor.  Not a bad start.  Note that this level of performance is not possible if the production is done at a remote location and the product is frozen for delivery.

Hope this proves useful.

Hacking resilience with you,

John Robb

One final note:  Perch and Zebra Mussels

Here’s some interesting insight into how regional environmental disruption has increased Sweet Water’s potential for success:

The Friday night fish fry, with Perch and Blue Gill as the fish of choice, is part of Wisconsin tradition.  Unfortunately, that’s gotten much more expensive due to regional environmental disruption of nearby Lake Michigan, once the source of most of the fish eaten during fish fries.  Fresh water Zebra mussels from southwest Russia found their way into the lake and have decimated the once abundant perch population.

The perch population has plunged from 24.6 million in 1990 to 316 thousand in 2010.   Wow. And that drop occurred even though perch fishing on the lake has been banned since 1996.   Needless to say, this environmental disruption has driven up the price of local perch.  It’s now pricing out at $15 a pound for fillets.

I’ll talk more about this disruption dynamic in the future on how our efforts to become resilient can benefit from it.


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  • OWSBuenosAires

    A nice income maximization hack for the aquaponics setup is a kitchen as you said,

    but not any kitchen, a kitchen that uses mostly fish and herbs,

    a kitchen that can seize on the extreme freshness of the fish, namely: A Sushi Kitchen.

    The authenticity factor of such an arrangement would be huge.

    The cost structure of such an operation would be very good,

    since most of the cost of a sushi kitchen is fish,

    and since that fish once purchased, needs to be used or trashed

    because of sushi food safety issues.

    In this arrangement you can kill the fish on demand, wasting no fish,

    and in addition provide your customers the freshest fish possible,

    reducing food waste and adding value at the same time.

    Selling the fish in this arrangement captures all the value addition that is possible

    with fish and creates the maximum amount of jobs, and demand for people with different

    skill-sets, from the people that grow/raise the food to the cooks, to the delivery drivers

    to the pretty girl that serves it to you.

    • johnrobb

      OWS, Problem is that the sushi that is in demand can’t be raised in a kitchen. JR

      • OWSBuenosAires

        The sushi that is in supply can’t be raised in a kitchen,

        I did my research yesterday before posting and both Tilapia, Perch and Blue Gill

        are good for sushi, the latter two being considered delicious.

        It is true than none of these lake fish are the traditional Japanese fishes used for

        sushi, but that is merely an issue that these fishes are not abundantly available in Japan,

        they use ocean fish because that is what is available there.

        In inland America and any other inland community it the natural adaptation

        would be to use locally available fish for sushi, specially in an RC since the alternative

        is to ship the ocean fish from the coast, so an RC sushi shop should use local fish, and since most communities are away from the coast lake fish should be the primary source.

        If people living in RC’s want to continue eating sushi this lake fish adaptation should take place. In addition, other ocean species could be raised, just not in the kitchen,

        there could be a fish raising facility separated from the kitchen.

        Go Inland.

        • johnrobb

          Thanks OWS.

      • OWSBuenosAires

        The sushi that is in demand/supply can’t be raised in a kitchen, that is true,

        it can’t be raised outside of a kitchen in an aquaculture setup either

        cause it requires salty moving water as in salmon farms.

        The sushi that is in demand/supply is not a resilient sushi, since the species used

        are the ones that are available in japan, traditional sushi uses this species

        because they are found abundantly in the ocean surrounding Japan.

        Sushi in inland communities (most of them) to be resilient should use

        species that are available/farmable locally. For most communities,

        these species are sweet water species, since most communities are inland communities

        far away from the ocean.

        So, for a community that likes to eat sushi not today but tomorrow and the day after too,

        in this increasing energy cost environment where soon its not gonna be economically feasible to ship the ocean fish from the coast, sushi is gonna have to use sweet water

        fish species.

        When its no longer feasible to ship (fresh)fish from the coast, it wont matter

        what the demand for sushi is, the supply is gonna only possibly be sweet water

        sushi, or no sushi.

        • johnrobb

          OWS, Thank you so much for the research. JR

  • Matt Smaus

    Yes. This is the kind of analysis I’m looking for at your site, John. Good, hard facts to suggest viable strategies for implementation. Case studies are great. Go even deeper if you have the time! The more you can dig into this stuff, the more contented I’ll be.

    • johnrobb

      Thanks Matt. JR

  • DC

    Re: Zebra Mussels…and now they’re starting to find these amphibious Snakefish invading the Great Lakes:

    • johnrobb

      DC. Oh joy. JR

  • matt heath

    Some notes from the F.A.Q. page from the folks at friendly aquaponics (hawaii):

    What is the most important thing to know about aquaponics?

    That it’s not about raising fish! Although the fish in aquaponics systems attract the most attention, the fish portion of the operation is costly both in terms of consumables and labor, and does not produce a profit unless combined with the vegetable income. Based on our last two years experience with commercial systems, the fish portion brings in 8% of the total income, while the vegetable portion brings in 92%. The problem with this is that the fish part of the operation creates a large percentage of the operating costs, for fish food, electricity for aeration, and labor for feeding, breeding, and harvesting the fish; while bringing in the small income percentage noted.

    When you try to grow MORE fish in the temperature range we are farming in (70-76 degrees F), with the fish food costs we have ($0.90/pound), the electricity costs we have ($0.44/KWhour), and the labor costs we have ($12/hour or more), EVEN with the price we’re getting for our fish ($5/pound) the more fish we try to grow, the MORE money we LOSE on the fish part of the operation. This means that if you are considering commercial aquaponic production, you should get accurate numbers for fish production from a farmer in your area rather than just stick an income number into your spreadsheet. If you ever hear a consultant who tells you can grow “X” amount of fish in the system they design, you have just heard a completely misleading statement; because the amount of fish you can grow in any system is entirely dependent on the system water temperature (plus MANY other factors they often forget to mention). Aquaculture businesses that have failed outnumber those that survived by ten to one.

    I would like more information about your commercial aquaponics plans. How large of an area does it cover, what are the construction costs, & what is the projected income from each one? We are looking to sell our business & build a hydroponics farm in the next 6-12 months.

    This is a difficult question to answer, because prices are locale-sensitive, and there is a huge difference in potential income between a system growing cabbage and one growing strawberries, for example. There are two “standard” systems of 1,024 and 4,096 square feet in the plans, and information on how to scale systems to any size you wish, including information on how to size blowers, pumps, and air and water lines appropriately. We have about 5,400 square feet of growing area, plus the processing facility for that, the walkin fridge, 1,200 square feet of sprouting tables, planting shed, tilapia breeding tanks, and some other stuff in about 20,000 square feet of total area. We are grossing about $150,000 a year on this now, at Hawaii prices (but paying Hawaii prices for expenses also!).

    Comparing to normal soil farming, how much more veggie production can be achieved in the same size area from aquaponics system?

    We experience vegetable maturity in half the time or less that the same vegetable takes in soil; and we can plant four to five times as densely as one can in soil because our nutrients do not get depleted by a crop, but rather are constantly flowing past the vegetable roots and being replenished in the fish tank.

    • johnrobb

      Matt, Thanks much. Interesting that the Sweet Water operation reversed that ratio (likely because they ran out of room). So, what they did was less aquaponics and more aquaculture. JR

  • matt heath

    Electricity where I live is slightly less than 10 cents per KWH, (about 80 percent less than in their setup), and labor can be had all day for $8 an hour (33 percent less).

    On another note, I agree, there are several areas that I would look into as far as increasing profit. If their whole and unprepared fish is going for $5 a pound wholesale, then there is a lot of room on the upside for profit if they do some value adding and filet it themselves like Robb pointed out. They could also vertically integrate and offer the fish Retail, themselves. A lunch only shop would allow them to move some of their product at Retail prices. Maybe an alternative “restaurant” out of a truck? Mobile fish fryer?

    • johnrobb

      Thanks Matt. The question you need to ask before building a resilient business: Is it fresh and local to the customers? JR

      • matt heath

        If a person was trying to maximize freshness, you couldn’t beat siting it in a city. In the middle of your customers. You would have minimal transportation costs to deliver to market.

        • Matt Smaus

          Matt- nice sleuthing. Important to interrogate our enthusiasm throughout this learning process….

  • Dave

    Actually almost all blue gill, crappie, and other pan fish are eaten at home in my experience. The Friday night fish fries at the Veterans halls, are generally perch and walleye (from Canada), rye bread w/ butter, with Manhattans w/ bitters or beer to wash it all down and I greatly miss them till I go back an visit.

    • johnrobb

      Dave, Your description is making me miss them and I’ve never been. JR

  • Burgundy

    Nice. It is on my “to do” list for this year to build a pilot aquaponics system using 1000ltr IBC tanks. Although I have to build the building to house it first and find the money and time. But apart from that it is a go.

    I had a “sourcier” (water dowsing) drop by today to locate possible locations for a well and one was near the site for the aquaponics.

    The Sweat Water aquaponics looks like quite an expensive setup and looking at the photos on their site, they seem to be using grow lights for the vegetables.

    • johnrobb

      Burgundy, Keep us up to date on your progress. JR

  • Molly Stanek

    Interesting post, and a great topic of discussion. As the former Assistant Director of Horticulture at Sweet Water (up until last April), I can tell you that your estimates seem extremely generous to me.

    There are currently 5 large fish tanks, most of them are closer to 9,000 gallons in size and a handful of smaller tanks. Due to the imbalance of fish and plants (as pointed out by a previous commenter), there is an inherent weakness in the fish growing part of the system. When the tanks are stocked at a one fish per gallon ratio as you suggest, the fish grow slowly if at all because the water quality suffers due to inadequate filtration and aeration. In my experience while there, the fish took an average of 12 months to reach harvest size, costing more money to be spent on feed and energy over that time.

    As for the plants, I can only say that the greatest frustration while I was there was the lack of growing space available in the indoor facility. At maximum capacity, there were fewer than 2,000 square feet of growing space in the entire facility, and even in my most optimistic projections (all half pound lettuce heads grown in 5 weeks at an extremely close spacing) the amount of leafy greens that could be produced was around 1500 pounds per month. And in my entire time there we never sold more than 700 pounds in a month because the systems were so imbalanced that pests became an enormous challenge.

    Aquaponics certainly holds a lot of promise. I just sincerely believe that Sweet Water’s model – which is based off of Growing Power’s – is not the way to go. There have been several businesses that have tried to replicate Growing Power’s tiered model and have gone out of business within a year or two. I left Sweet Water (along with a third of the other staff) because they weren’t able to pay me for months at a time. However, I learned an incredible amount and wouldn’t be on the current path that I am without my time there.

    The model that Sweet Water sets is definitely something to be learned from – not replicated, and from my knowledge of the systems and my experiences there, I doubt it is as profitable as you project.

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