Reducing Phosphorus to Clean Up Lakes and Rivers
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:
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:
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.
Wisconsin farmers and wastewater dischargers are already taking actions to cut phosphorus pollution to lakes and rivers.
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.
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.
- 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
- 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.
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.
Links relating to phosphorus control and research
- Wisconsin's Impaired Waters Program
- Wisconsin's Water Quality Standards -- Evaluation and Management
- Watershed Management