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Reducing Phosphorus to Clean Up Lakes and Rivers

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Select a subject area below for specific information on phosphorus reduction.


weed and algae growth in Wisconsin waters (c) Will Stites
Excess phosphorus flowing into lakes provides nutrients that can spur weed and algae growth in Wisconsin waters.
© Will Stites


See which lakes and rivers are impaired by phosphorus by selecting "total phosphorus" from the pollutant drop down menu:

Peggy McAloon
Lakefront owners like Peggy McAloon are concerned about health issues and property values from pea green conditions caused by phosphorus.


Read how landowners and local governments surrounding one lake are tackling the problem together:

Less P is Key
Wisconsin Natural Resources magazine August 2010

Skin irritation
Blue-green algae fueled by phosphorus in a Dunn County lake in 2007 caused skin irritation in people spending time in the water.

Wisconsin's taken another important step to curb the phosphorus pollution that can fuel harmful algae, excessive plants and muddy water in many lakes and rivers. Changes to administrative rules aimed at cutting phosphorus coming from farms and industrial and municipal wastewater dischargers were adopted by the state Natural Resources Board in June 2010 and are now in effect.

The rule changes create a comprehensive approach that enables Wisconsin to reduce phosphorus pollution cost-effectively and cooperatively. They build on decades of efforts to cut sediment and phosphorus entering our lakes and streams.

Reducing phosphorus entering phosphorus-polluted waters will help increase the waters' recreational use and surrounding property values as water clarity increases, according to economic research. And protecting lakes and rivers with good water quality from phosporus pollution will save taxpayers and local communities money.

Why phosphorus is a problem

Phosphorus has long been recognized as the controlling factor in plant and algae growth in Wisconsin lakes and streams. Small increases in phosphorus can fuel substantial increases in aquatic plant and algae growth, which in turn can reduce recreational use, property values, and public health:

  • One-quarter of the more than 700 waterbodies on Wisconsin's impaired waters list fail to meet water quality standards due to phosphorus pollution.
  • Dozens of waters statewide experience harmful algal blooms fueled by the nutrient, posing a health threat to people, pets and livestock. Over the past 3 years, 98 people have reported health complaints related to such blooms.
  • Smelly cladophora fueled by phosphorus washes ashore Lake Michigan beaches. Nuisance Algae (Cladophora) In Lake Michigan
  • Recent statewide stream assessment data suggests that thousands of streams may have excess phosphorus levels. In addition to decreasing the dissolved oxygen that fish and other aquatic creatures need to survive, such excess phosphorus causes major changes in lake and stream food webs, which ultimately result in fewer fish and fish predators.

Where phosphorus comes from

Phosphorus is an essential nutrient that occurs naturally, mainly as phosphate, and has been mined for use in fertilizer, detergent and animal feed. It's in our food, in our waste, and in that of other animals.

Phosphorus entering our lakes and streams comes from "nonpoint" or "runoff" pollution. Such pollution occurs when heavy rains and melting snow wash over farm fields and feedlots and carry fertilizer, manure and soil into lakes and streams, or carry phosphorus-containing contaminants from urban streets and parking lots.

Phosphorus also comes from the "point sources" - piped wastes such as municipal and industrial wastewater treatment plants that release liquid effluent to lakes and rivers or spread sludge on fields; and from natural sources, including past phosphorus loads that build up in lake bottom sediments.

How much these sources contribute to phosphorus problems in a lake or river varies widely based on land use in a watershed and the number of point sources discharging into that lake or river. There are situations where runoff contributes more than 80 percent of the phosphorus, and situations where point sources contribute more than 80 percent. Most commonly, both point sources and nonpoint sources contribute phosphorus.


Limits set for phosphorus in waterbodies

Changes to Chapters NR 102 and NR 217 of the Wisconsin Administrative Code set the highest levels of phosphorus that could be allowed in lakes, rivers and the Great Lakes and still support the fish and other aquatic life they were capable of supporting. Different numerical levels are set for five categories of lakes and reservoirs, for rivers and streams, and for the Great Lakes.

How rule changes affect industrial and municipal wastewater dischargers

The changes to NR 217 of the Wisconsin Administrative Code establish the procedures for setting limits on the amount of phosphorus permitted facilities could discharge. Permits issued after the Jan. 1, 2011, effective date of the rule will incorporate the new phosphorus requirements.

Many statewide industrial and municipal wastewater treatment plants have already done a good job in reducing phosphorus to meet 20-year-old statewide phosphorus limits.

The average discharge from point sources is 0.5 milligrams per liter of phosphorus -- well under the 1 milligram per liter of phosphorus allowed since 1993 -- and some facilities discharge at 0.3 or lower. Some plants may need to do additional work and upgrades to reduce phosphorus loads, but the rule includes flexible options for implementing cost effective reductions.

The flexible options include extended compliance schedules to meet the more stringent limits and the ability for some dischargers to meet less stringent limits if they work with upstream nonpoint sources to rachet down their phosphorus pollution. The rule changes also allow dischargers to seek a variance if the surrounding communities would suffer undue economic hardship by meeting the phosphorus limits. Dischargers will have the options of pollutant trading and adaptive management, which both allow them to working with upstream sources to reduce phosphorus coming from those operations in lieu of reducing phosphorus at their wastewater treatment plants.

»»Wisconsin Phosphorus Rules

How rule changes affect municipalities

About 75 percent of municipalities met a 2008 deadline for reducing by 20 percent the particulate pollutants carried in their stormwater, with phosphorus one of the major pollutants attached to particles. The rule changes give some municipalities more time to meet a 2013 deadline to reduce particulate pollutants in stormwater by 40 percent. Municipalities asked for more time, saying the economic recession made it difficult for them to make the needed investments or to ask their ratepayers to absorb higher fees.

How rule changes affect construction sites

Developers must meet stiffer requirements aimed at preventing or reducing sediment eroding from soil stock piles on the site for more than seven days.

How rule changes affect farmers

The changes to Natural Resources Chapter 151 require farmers to curb phosphorus potentially coming off their fields to an eight-year average that factors in land slope, phosphorus levels in their soil and average precipitation levels.

Based on UW-Madison research, the DNR estimates that 80 percent of cropland already meets this standard. The rule changes -- and new technology developed by UW-Madison -- give the state the tools necessary to identify and address those farms contributing excess phosphorus and leave the rest alone. And changes to related rules, Natural Resources Chapter 153, now allow DNR to steer grant money to those farms that need to make changes.

NR 151 Implementation Strategy


Phosphorus reduction timeline

Wisconsin's 2010 phosphorus rules represent a broad-based approach aimed at enabling Wisconsin to reduce phosphorus pollution effectively, cost-efficiently, and cooperatively. They build on decades of efforts to cut sediment and phosphorus entering our lakes and streams.


Major milestones in efforts to cut phosphorus pollution in Wisconsin.

Nation's first soil watershed project

The federal government, along with desperate, but willing, landowners and farsighted bankers, launched the nation's first watershed project in the mid-1930s to curb soil erosion in the 92,000-acre Coon Valley south of La Crosse and save the productivity of the soil. Since then, the federal government, state and local governments have worked with farmers through a variety of voluntary programs to significantly curb soil loss in Wisconsin and elsewhere but phosphorus pollution from farms remains a problem.

Soil conservation efforts

contouring and strip farmingSoil conservation efforts like contouring and strip farming started 75 years ago in Vernon County. Today, those measures help reduce runoff and erosion. Area trout streams are cleaner as a result.
Photo © Natural Resources Conservation Service

Related reading

Restoring Life to a Watershed
Wisconsin Natural Resources magazine, February 2002

Federal Clean Water Act passed

wastewater treatment plantU.S. Congress passes the Water Pollution Control Act, which makes it illegal to discharge pollutants without permits and establishes two goals: make the nationís wasters fishable and swimmable by 1983 and eliminate discharges to waterways. Wisconsin in 1983 became the first state to meet the "fishable and swimmable" goals. Congress has failed to reauthorize the Clean Water Act since 1987. The result has been the Clean Water Act does not address some of the biggest water pollution problems of today, including phosphorus pollution.

Related reading

Clear intentions
Wisconsin Natural Resources magazine, October 2002, article

Mid 1970s
Phosphorus limits for wastewater discharges to the Great Lakes

Consistent with the Great Lakes Water Quality Agreement, municipal and industrial dischargers of phosphorus in the Great Lakes Basin required to reduce their discharges to 1 miligram per liter.

Wisconsin moves to curb runoff pollution

Program created to protect Wisconsin waters from runoff pollution by offering to share costs with landowners and communities that take steps to keep soil, fertilizer, street debris and construction site dirt from washing into streams and lakes.

Largescale livestock operations required to get water quality permits

dairy farmWisconsin starts requiring farms with at least 1,000 animal units, equal to 700 milking cows, 1,000 beef steers or 55,000 turkeys, to get water quality permits detailing the manure storage, spreading, and other practices they must follow to reduce the risk of manure spills or runoff to lakes and streams since these operations produce at least a much organic pollution as a city of 18,000 people and spread it on fields, often without treatment.

Statewide limits on phosphorus in wastewater discharge

Municipal and industrial dischargers of phosphorus statewide are required to meet a technology-based limit of 1 miligram per liter of phosphorus.

Wisconsin sets runoff performance standards and prohibitions

Wisconsin passes the nation's most complete rules to cut polluted runoff from farms, urban areas, construction sites and roads.

Related reading

Reining in polluted runoff
Wisconsin Natural Resources magazine, June 2003, article

CAFO rules tightened

Changes to rules governing the state's largest livestock operations, operations known as Concentrated Animal Feeding Operations required to get a water quality permit, go into effect to reduce phosphorus and other nutrients entering lakes and streams. Key provisions prohibit spreading liquid manure on frozen or snow-covered ground with limited exceptions and ban spreading solid manure on frozen or snow-covered ground during February and March unless it's immediately incorporated.

Phosphorus banned from lawn fertilizer

dairy farmBeginning April 1, 2010, fertilizer that is labeled as containing phosphorus or available phosphate cannot be applied to lawns or turf in Wisconsin unless the fertilizer application qualifies under certain exemptions. Ban on phosphorus.

Related reading

Turf Fertilizer Regulations and Professional Lawn and Landscape Businesses [exit DNR]
Wisconsin Department of Agriculture, Trade and Consumer Protection

Phosphorus levels curbed in dishwater detergent

Beginning June 1, 2010, it's illegal to sell or use household dishwasher detergent with more than .5 percent phosphorus by weights. The law ends an exemption for dishwater detergent to a 1970s rule limiting phosphorus in cleaning products.

Limits set on total phosphorus allowed in waterbodies and rules tightened

Rules setting phosphorus water quality standards criteria and rule changes aimed at reducing phosphorus in wastewater discharges from industrial and municipal wastewater dischargers take effect December 1, 2010. Rule changes aimed at reducing phosphorus in runoff from farms take effect January 1, 2011.

Pollution "budgets" set to curb phosphorus in several impaired waters

Wisconsin releases reports that set pollution reduction goals for phosphorus and sediment for several major waters including the Rock River and tributary streams and the Lower Fox River and Green Bay. The federal government requires that the phosphorus budgets, known as Total Maximum Daily Loads, be developed for lakes and rivers with impaired water quality, and then implementation plans be developed to meet the phosporus reduction goals.


Changes to agricultural, urban and construction runoff rules
Mary Anne Lowndes
DNR Runoff Management Section Chief
Changes to grant programs to help farmers install phosphorus controls
Mary Anne Lowndes
DNR Water Resources Management Specialist
Phosphorus water quality standards and permit procedures
Amanda Minks
DNR Water Quality Specialist
Phosphorus ban on lawn fertilizer
Charlene Khazae
DATCP fertilizer program manager
Wisconsin Department of Agriculture, Trade and Consumer Protection
Turf Fertilizer Regulations and Professional Lawn and Landscape Businesses [exit DNR]
Phosphorus ban in dish detergents
Michelle Reinen
Bureau of Consumer Protection director


National report documents elevated nitrogen and phosphorus widespread in streams and groundwater

A comprehensive national analysis of nutrients in streams and groundwater from 1992 through 2004 shows that levels of phosphorus and nitrogen have stayed the same since the 1990s or increased despite major federal, state, and local efforts to control point and non-point sources and transport of these nutrients.

Nutrients in the Nation's Streams and Groundwater: National Findings and Implications [PDF exit DNR]

National report documents pollution and public health concerns linked to nutrients

A national panel of experts convened by the U.S. Environmental Protection Agency in August 2009 issued a report calling nutrients such as phosphorus and nitrogen "a growing environmental crisis" not just for fish and aquatic life, but also for drinking water supplies.

An Urgent Call to Action [PDF exit DNR]

Links relating to phosphorus control and research

External sites

Wisconsin farmers and wastewater dischargers are already taking actions to cut phosphorus pollution to lakes and rivers.

Last revised: Sunday, December 10, 2017

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