Q&A: The Nature Conservancy's John Nelson Talks Watershed Phosphorus Reduction

There are more ways to keep phosphorus out of waterways than adding new processes. Adaptive management and nutrient trading look to limit runoff from upstream sources.
Q&A: The Nature Conservancy's John Nelson Talks Watershed Phosphorus Reduction
John Nelson

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Clean-water plants facing tough new permit limits on phosphorus increasingly look upstream. Some states allow innovative methods for phosphorus reduction in waterways that don’t necessarily involve costly new treatment processes or plant upgrades.

Wisconsin’s regulations, for example, allow adaptive management: A clean-water agency can work with property owners upstream to limit phosphorus runoff, instead of or in addition to cutting its own phosphorus discharges.

Another approach is nutrient trading, a market-based approach in which facilities can come into compliance by buying and selling rights to emit phosphorus. Such approaches have worked well in, for example, curtailing the air pollutants that cause acid rain.

John Nelson, a project manager with The Nature Conservancy, has worked on phosphorus reduction in some watersheds in eastern Wisconsin and has advised clean-water agencies looking at innovative approaches. In an interview with Treatment Plant Operator, he shared ideas on how agencies can go about finding opportunities for phosphorus reduction on farms.

TPO: What role has The Nature Conservancy been playing in phosphorus reduction in watersheds?

Nelson: We initially worked on a project in Wisconsin in which we compared a small test watershed, where we wanted to ask farmers to change practices, against a control watershed, where farmers were not asked to change. We looked at land use in both watersheds and came up with targeted efforts on a small percentage of the land base. We believe, and it’s pretty well proven, that a small percentage of fields actually contribute the most phosphorus runoff. Why invest money across an entire watershed? Why not target it where it will have the most effect?

TPO: What work have you done with municipalities to reduce upstream phosphorus contributions?

Nelson: The City of Plymouth, Wisconsin, approached us asking whether we could help them with phosphorus reduction. In working with them, we’re trying to build a model of how a municipality would approach looking for nutrient credits in a watershed. We’re using some of the same reasoning as in our original test and control watersheds, trying to find the hotspots.

TPO: How can a clean-water agency work with these innovative phosphorus reduction approaches?

Nelson: There are three basic ways it can be done. First, they could simply make sure the stream they discharge to meets the state standard for phosphorus. They would work toward that by helping clean up runoff problems on farms. Second, they could trade for credits in the watershed, either with a private landowner — a farmer in most cases — or with another facility on the same stream that is operating well below its discharge limit. A third way that the U.S. EPA is now reviewing would allow a city to pay a fee for each pound of phosphorus above its limit. That money then could be used by an entity such as a county land and water conservation department to pay for general improvements in the watershed.

TPO: Based on your experience, what advice would you give to clean-water operators looking upstream to reduce phosphorus?

Nelson: A first step would be to go to the county land and water conservation department and talk to the field staff to get an idea what the potential is for reducing phosphorus. Then, most communities would likely hire a consultant to get details in terms of comparing the cost of a plant upgrade to going out and buying credits. Generally, you would expect buying credits to be cheaper, but that may not always be true. It depends on the condition of the watershed. If the farming practices are already good, there may not be a lot of credits to be had.

TPO: Are there other simple ways to investigate farming practices in a watershed?

Nelson: Another easy way to start is to look at aerial photos of a township. You can pick out concentrated flow areas where there is a lot of erosion. It’s not terribly difficult to get a general idea. If you want to get really hard numbers, you have to go to the farms and do measurements of soil phosphorus levels and actually look at the farming practices.

TPO: What about analytical tools for assessing risk of phosphorus runoff?

Nelson: Wisconsin has the SNAP-Plus soil nutrient application planner. It’s a model developed by the University of Wisconsin Soil Sciences Department. You enter variables like the soil type, the slope, presence or absence of streamside buffers, and farming practices such as moldboard versus chisel plowing. The model calculates a phosphorus index value for each field that measures the risk of phosphorus moving across that field into a waterway.

TPO: Who would actually deploy this model?

Nelson: It could be a crop consultant hired by a farmer. It could be county land and water conservation staff. It could be the farmers themselves. Farmers have the ability to write nutrient management plans based on the SNAP-Plus model. Some are quite adept at using the technology.

TPO: In general, what do you observe today about the quality of farming practices in terms of limiting runoff to creeks and rivers?

Nelson: Farming practices have improved a lot. I suspect most farmers who were the biggest problems probably are no longer in business. The big dairies — the concentrated animal feeding operations (CAFOs) — are under stringent rules. Smaller farms see less scrutiny, although they have rules to follow as well. There is still a lot of room for improvement, but we’re encouraged. Things we promote, such as cover crops, that benefit water quality also benefit farmers in the long run. To sustain a good farming living, they need healthy soil. They know that.

TPO: Who decides how much phosphorus credits are worth?

Nelson: The Wisconsin Department of Natural Resources has some standards published in its nutrient trading handbook. In the end it depends on what practices the farmer installs. If a city were to get a farmer to make a change, the city would likely pay the farmer for whatever was done. It might be an annual cost, or it might be an annual contract. It varies greatly.

TPO: Would you see that searching for credits and encouraging farmers to change practices would be outside the core competency of a typical clean-water agency?

Nelson: I’m not sure that is true. I think operators can pretty easily understand the process. I think the team in Plymouth is anxious to get going. They have hired a consultant to help them evaluate their best options.

TPO: Can anything be done within a city’s borders to reduce phosphorus runoff?

Nelson: Absolutely. There are practices like installing stormwater retention ponds and sweeping streets to keeping leaves out of storm drains.

TPO: What kinds of farming practices can be employed to reduce phosphorus?

Nelson: Besides planting cover crops and stream buffers, they can change their crop rotations. Suppose a farmer plants corn for two years and soybeans for a year after that. If he added a year of winter wheat to the rotation, that could help. Farmers in some areas could go with no-till planting. For applying fertilizer, some farmers put it in a band next to the seedbed instead of broadcasting it across the field. They get more benefit from the fertilizer they use.

TPO: What about improving manure management?

Nelson: Manure management is huge, and farmers are getting better at it. They have better techniques for putting it on. Some apply a cover crop seed along with the manure, so the plants can grab a hold of some of the nutrients and hold them there until spring. There are different ways of applying manure so that it’s less likely to run off.

TPO: Is there a human side to this approach to phosphorus management? How important is communication as part of the process?

Nelson: It’s very important for a community using this approach to let anyone who could be affected know what’s going on. Don’t hide the plans until the last minute. Keep people informed. That includes town governments. Trust is important, especially with farmers. It takes a while to develop that trust and show that everybody is trying to work toward one goal of a better society. Take the attitude that everybody can come out a winner.


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