While pollution controls put in place over the last five years have lowered the amount of nutrients and sediment entering the nation’s largest estuary, new data show that agricultural sources have sent more nitrogen and sediment into the Bay since 2007 than previously thought.
Excess nitrogen, phosphorus and sediment can impair water quality: nitrogen and phosphorus can fuel the growth of harmful algae blooms, while sediment can suffocate shellfish and block sunlight from reaching underwater plants.
Each year, the seven watershed jurisdictions report the steps they have taken to lower the nutrients and sediment entering rivers and streams. Bay Program experts run this information through a suite of computer simulations, which generate pollution load estimates that show us how far our partners have come toward meeting the Bay’s “pollution diet.” When bolstered with new data on population size, land use and agricultural commodities, these simulations show a drop in pollution since 2009—including a six percent drop in nitrogen, an 18 percent drop in phosphorus and a 4 percent drop in sediment—but a two percent rise in nitrogen and sediment loads between 2013 and 2014.
A shift in agricultural commodities could explain this rise in nitrogen and sediment loads. According to data from the U.S. Department of Agriculture’s Census of Agriculture, several states have seen a surge in corn plantings since 2007. Because corn requires nitrogen-rich fertilizer that can leach off the ground and into local waterways, more corn plantings led to more nitrogen loadings than anticipated when pollution targets and reduction milestones were set.
The Bay Program uses the best possible data and information to track our progress toward restoring water quality. By incorporating new data into our computer simulations and pollution load estimates, we are allowed a more accurate picture of pollution in the watershed and a better understanding of the actions that are needed to reach our clean water goals. Because these computer simulations generate pollution load estimates using long-term average weather conditions, it’s possible for these estimates to differ from those that are based on water quality monitoring data; the latter can vary with the amount of rainfall in a given year.
“Each year, we employ the most current data and up-to-date science [to] offer the highest quality information to the public on pollution reductions resulting from Chesapeake Bay Program partners’ continued efforts. While we… have a lot of work to do… we are making steady progress toward meeting water quality goals,” said Bay Program Director Nick DiPasquale in a media release.
These pollution load estimates are just one in a suite of tools the U.S. Environmental Protection Agency (EPA) uses to evaluate whether jurisdictions are on track to meet the Total Maximum Daily Load (TMDL) and its two-year milestone commitments. The EPA also considers data and information on best management practice implementation, best management practice effectiveness and jurisdictions’ progress toward putting programs in place to achieve pollution cuts. It is expected to release interim assessments of jurisdictions’ work in May and conduct the next full two-year assessment in 2016.
The amount of nutrient and sediment pollution that flowed from nine major rivers into the Chesapeake Bay remained below the 25-year average in 2013. While scientists expect this to have a positive impact on the long-term health of the nation’s largest estuary, much of the Bay’s tidal waters remain impaired: between 2011 and 2013, just 29 percent of the water quality standards necessary to support underwater plants and animals were achieved.
Excess nutrients and sediment are among the leading causes of the Bay’s poor health. Nitrogen and phosphorus can fuel the growth of harmful algae blooms that lead to low-oxygen “dead zones” that suffocate marine life. Sediment can block sunlight from reaching underwater grasses and suffocate shellfish. Lowering the amount of nutrients and sediment moving from our streets, lawns and farm fields into the water is a critical step in the restoration of the Bay, and scientists have attributed the below-average pollution loads of 2013 to below-average river flow and the pollution-reducing practices our partners have put in place on the land.
Because pollution in our rivers has a direct impact on water quality in the Bay, the Chesapeake Bay Program tracks both environmental indicators to gain a wider picture of watershed health.
Pollution loads and trends
Our partners at the U.S. Geological Survey (USGS) monitor nutrient and suspended sediment loads delivered from the large watersheds located upstream of nine river monitoring stations to the Chesapeake Bay. Together, these stations—which are located on the Appomattox, Choptank, James, Mattaponi, Pamunkey, Patuxent, Potomac, Rappahannock and Susquehanna rivers—reflect loads delivered to the Bay from 78 percent of its watershed. Data show that nutrient and sediment loads measured in water year 2013 were below the long-term average.
Water quality standards achievement
The Chesapeake Bay Program measures progress toward the achievement of water quality standards in the Bay and its tidal tributaries using three environmental factors: dissolved oxygen, water clarity or underwater grass abundance, and chlorophyll a. Data are assessed in three-year periods. After more than a decade of steady improvement between 1989 and 2002, the attainment of water quality standards has seen mixed results. Changes seen in the past 10 years have not been statistically significant, and it is likely that the slow recovery of underwater grasses in the Upper Bay has stalled some water quality improvements.
Underwater grasses offer important habitat to underwater species and have a direct impact on water quality: healthy bay grass beds add oxygen to the water, absorb nutrient pollution, reduce wave energy and help suspended and potentially light-blocking particles like sediment settle to the bottom. Between 2009 and 2012, unfavorable growing conditions caused bay grasses to decline across the region. In 2011, for instance, heavy rains and the resulting runoff clouded the water during the spring growing season. That fall, Hurricane Irene and Tropical Storm Lee muddied the water again. Because water quality is reported in three-year assessment periods—and the most recent assessment period spanned 2011, 2012 and 2013—it is likely this drop in bay grass abundance influenced water quality results. But bay grasses have shown resilience: a dense bed on the Susquehanna Flats persisted through the storms of 2011, and showed how resilient such grass beds can be to disturbances in water quality. If bay grasses continue the recovery that took place in 2013, there could be positive effects across the wider Bay ecosystem.
Upgrading wastewater treatment technologies has lowered pollution in the Potomac, Patuxent and Back rivers, leading researchers to celebrate the Clean Water Act and recommend continued investments in the sewage sector.
Introduced in 1972, the Clean Water Act’s National Pollutant Discharge Elimination System permit program regulates point sources of pollutants, or those that can be pinpointed to a specific location. Because wastewater treatment plants are a point source that can send nutrient-rich effluent into rivers and streams, this program has fueled advancements in wastewater treatment technologies. Biological nutrient removal, for instance, uses microorganisms to remove excess nutrients from wastewater, while the newer enhanced nutrient removal improves upon this process.
Researchers with the University of Maryland Center for Environmental Science (UMCES) have linked these wastewater treatment technologies to a cleaner environment. In a report released last month, five case studies show that wastewater treatment plant upgrades in Maryland, Virginia and the District of Columbia improved water quality in three Chesapeake Bay tributaries.
The link is clear: excess nutrients can fuel the growth of algae blooms, which block sunlight from reaching underwater grasses and create low-oxygen dead zones that suffocate marine life. Lowering the amount of nutrients that wastewater treatment plants send into rivers and streams can reduce algae blooms, bring back grass beds and improve water quality.
In New Insights: Science-based evidence of water quality improvements, challenges and opportunities in the Chesapeake, scientists show that new technologies at Baltimore’s Back River Wastewater Treatment Plant led to a drop in nitrogen concentrations in the Back River. Upgrades at plants in the upper Patuxent watershed led to a drop in nutrient concentrations and a resurgence in underwater grasses in the Patuxent River. And improvements at plants in northern Virginia and the District lowered nutrient pollution, shortened the duration of algae blooms and boosted underwater grass growth in the Potomac River.
Image courtesy Kevin Harber/Flickr
The Chesapeake Bay Program tracks wastewater permits as an indicator of Bay health. As of 2012, 45 percent of treatment plants in the watershed had limits in effect to meet water quality standards. But a growing watershed population is putting increasing pressure on urban and suburban sewage systems.
“Further investments in [wastewater treatment plants] are needed to reduce nutrient loading associated with an increasing number of people living in the Chesapeake Bay watershed,” New Insights notes.
Over the last four years, pollution controls put in place by Chesapeake Bay Program partners have lowered the amount of nutrients and sediment entering the Chesapeake Bay. This is a critical step toward improving water quality and environmental health.
Each year, the seven jurisdictions in the watershed—which include Delaware, Maryland, New York, Pennsylvania, Virginia, West Virginia and the District of Columbia—report the steps they have taken to lower the nitrogen, phosphorous and sediment entering rivers and streams. Bay Program experts analyze this information using a suite of computer simulations, and the resulting estimates tell us how far these jurisdictions have come toward reducing pollution to levels that would lead to a healthy Bay.
Between 2009 and 2013, our estimates show that nitrogen loads to the Bay decreased 7 percent, phosphorous loads decreased 11 percent and sediment loads decreased 6 percent. As a whole, reductions in phosphorous and sediment are on track, but efforts to reduce nutrient and sediment pollution from urban streets, farm fields and onsite septic systems are lagging behind.
Excess nitrogen and phosphorous can fuel the growth of algae blooms that create low-oxygen “dead zones” that suffocate marine life. Excess sediment can block sunlight from reaching underwater grasses and suffocate shellfish.
But land-based actions—from upgrading wastewater treatment plants to managing nutrients on farmland—can reduce nutrient and sediment pollution. Jurisdictions will continue to put such actions in place in an effort to meet the pollution-reducing requirements set forth in the Chesapeake Bay Total Maximum Daily Load (TMDL), or “pollution diet.”
In June, the U.S. Environmental Protection Agency (EPA) is expected to release an assessment of jurisdictions’ progress toward this diet’s milestones. By 2017, partners should have practices in place to achieve at least 60 percent of the pollution reduction targets necessary to meet water quality standards in the Bay. Jurisdictions’ strategies to achieve these goals are outlined in their Watershed Implementation Plans (WIPs).
Over the last three years, estimates indicate that communities across the Chesapeake Bay watershed have made big reductions to the pollution they are sending into rivers and streams.
As part of the Bay’s “pollution diet”—or Total Maximum Daily Load—the six Bay states, the District of Columbia and the U.S. Environmental Protection Agency (EPA) have curbed the amount of nutrients and sediment running off of land and into local waters. According to data released today by the Chesapeake Bay Program, simulations show that partners have achieved more than a quarter of their overall pollution reduction goals.
Excess nitrogen and phosphorous can fuel the growth of harmful algae blooms that create “dead zones” and suffocate aquatic life. Excess sediment can block sunlight from reaching underwater grasses and suffocate shellfish.
But a number of land-based actions can reduce nutrient and sediment pollution. Towns and cities, for instance, can make technological upgrades to wastewater treatment plants and “green” roofs, sidewalks and parking lots to better capture stormwater runoff. Homeowners can install rain gardens in their backyards or plant big trees to boost forest cover in their neighborhoods. And farmers can protect streams from livestock and plant cover crops to hold soil in place.
Read more about reducing nitrogen, phosphorous and sediment in the Chesapeake Bay.
Over the past decade, smallmouth bass in five Chesapeake Bay tributaries have suffered from fish kills and perplexing illnesses—and nutrient pollution could be to blame.
According to a new report from the Chesapeake Bay Foundation (CBF), excess nitrogen and phosphorous in our rivers and streams could be behind two of the leading problems affecting smallmouth bass: first, the rapid growth of fish parasites and their hosts, and second, the expansion of large algae blooms that can lead to low-oxygen conditions and spikes in pH. When paired with rising water temperatures and ever more prevalent chemical contaminants, nutrient pollution seems to have created a “perfect storm” of factors that are making smallmouth bass more susceptible to infections and death.
Image courtesy Mr. OutdoorGuy/Flickr
In a media call, CBF President Will Baker called the smallmouth bass “the canary in the coal mine for the Bay’s rivers.” Because the fish is sensitive to pollution, problems within the population could indicate problems within the Bay.
Smallmouth bass in the Susquehanna, Monocacy, Shenandoah, Cowpasture and South Branch of the Potomac rivers have seen a string of recent health problems, from open sores and wart-like growths to abnormal sexual development. In the Susquehanna, smallmouth bass populations have plummeted so far that Pennsylvania has made it illegal to catch the fish during spawning season.
“Our fish are sick, our anglers are mad and my board and I—protectors of our [smallmouth bass] fishery—are frustrated,” said John Arway, executive director of the Pennsylvania Fish and Boat Commission. “Our bass, and our grandchildren who will fish for them, are depending on us to fix the problem.”
Image courtesy CBF
While specific causes of smallmouth bass fish kills and illnesses remain unclear, CBF has called on state and local governments to accelerate their pollution-reduction efforts in hopes of improving water quality and saving the driving force behind a $630 million recreational fishing industry. The non-profit has also called on the federal government to designate a 98-mile stretch of the Susquehanna as impaired, which would commit Pennsylvania to reversing the river’s decline.
“This is the moment in time to save fishing in our streams and rivers, as well as the jobs and quality of life that are connected to it,” Baker said.
After eleven years, $40 million and more than 16,000 linear feet of pipe, West Virginia is set to bring a new wastewater treatment plant online and make huge cuts to the pollution it sends into the Chesapeake Bay.
Under construction in West Virginia’s Eastern Panhandle, the Moorefield Wastewater Treatment Plant will replace four existing plants with one new system, marking a significant milestone in the headwater state’s efforts to curb pollution and improve water quality. Expected to go into operation this fall, the plant will remove 90,000 pounds of nitrogen and 93,000 pounds of phosphorous from West Virginia wastewater each year.
Funded by a range of sources—including the West Virginia Economic Development Authority, the West Virginia Department of Environmental Protection and the U.S. Environmental Protection Agency (EPA)—the new plant is heralded as evidence that thoughtful planning and forward-thinking—especially where pollution regulations are concerned—can help a community move toward conservation and environmental change.
In the 1990s, the hundreds of wastewater treatment plants that are located across the watershed could be blamed for more than a quarter of the nutrient pollution entering the Bay, as the plants pumped water laden with nitrogen and phosphorous into local rivers and streams. Such an excess of nutrients can fuel the growth of algae blooms that block sunlight from reaching underwater grasses and, during decomposition, rob the water of the oxygen that aquatic species need to survive.
But in the last decade, technological upgrades to wastewater treatment plants have surged, and the pollution cuts that result mean these plants now contribute less than 20 percent of the nutrients still entering the Bay.
According to Rich Batiuk, Associate Director for Science with the EPA, the uptick in upgrades can be attributed to a number of factors.
“Wastewater treatment plants have always been regulated,” Batiuk said. “But [until the last decade], there wasn’t the science or the political will or the … water quality standards that could drive the higher levels of wastewater treatment that result in lower levels of nitrogen and phosphorous flowing into the watershed.”
As the science behind wastewater engineering has improved and the incentives for implementing upgrades have grown, more plants have begun to make changes. Some implement a “zero discharge” plan, using nutrient-rich effluent to feed agricultural crops rather than excess algae. Others—like the Moorefield plant—expose wastewater to nutrient-hungry microbes that feed on nitrogen and phosphorous; the resulting sludge, modified without the addition of chemicals, can be turned into compost rather than fodder for the local landfill.
Such modern upgrades to otherwise aging infrastructure have been celebrated as a boon for local communities and the wider watershed. While the Moorefield plant will, in the end, curb pollution into the Bay, it will first curb pollution in the South Branch of the Potomac River, into which it sends its effluent.
"The South Branch of the Potomac is a unique place,” Batiuk said. “People fish there, they swim there. This new plant helps more than the Chesapeake Bay.”
And Moorefield residents—including the Town of Moorefield Public Works Director Lucas Gagnon—plan to witness this local change firsthand.
“The residents in this area are aware of the Chesapeake Bay and its needed [nutrient] reductions,” Gagnon said. “But the biggest benefit for the local folks will be the reduction of nutrients in local waterways.”
“There are many people that fish and boat the South Branch,” Gagnon continued. “When this plant goes online, the water quality will be greatly enhanced, and they will have a much cleaner, better river to enjoy.”
Virginia Gov. Bob McDonnell has signed into law a bill that prohibits the sale, use and distribution of lawn fertilizer containing phosphorus. The legislation will go into effect on Dec. 31, 2013.
The law also prohibits the sale of deicers containing urea, nitrogen or phosphorus. Additionally, golf courses must implement nutrient management plans by 2017.
Phosphorus is one of the two main types of nutrients that pollute the Bay and its local waterways. Too much phosphorus runoff leads to algae blooms and low-oxygen “dead zones” where underwater life cannot survive.
Nutrient pollution in the majority of the Chesapeake Bay region’s freshwater streams and rivers has decreased over the last 25 years, according to data from scientists with the U.S. Geological Survey (USGS) and the Chesapeake Bay Program.
Almost 70 percent of the watershed’s 32 monitoring locations show decreasing nitrogen and phosphorus levels, meaning fewer of these harmful nutrients are entering the Chesapeake’s local waterways. Approximately 40 percent of the sites show decreasing trends for sediment pollution.
Although this data may indicate long-term improvements in the health of the Bay’s streams and rivers, pollution loads to the Bay were higher in 2010 due to more rain, snow and river flow.
“These long-term trends indicate that pollution reduction efforts, such as improved controls at wastewater treatment plants and practices to reduce nutrients and sediment on farms and suburban lands, are improving water quality conditions in many areas,” said USGS scientist Scott Phillips. “However, nutrients, sediment and contaminants will need to be further reduced to achieve a healthier Bay and streams.”
Each day, billions of gallons of fresh water flow through thousands of streams and rivers that eventually empty into the Bay. This fresh water is known as “river flow.” In general, as river flow increases, more nutrient and sediment pollution is carried downstream to the Bay. Pollution levels in rivers vary greatly from year to year because they are influenced by rainfall. Scientists make adjustments to remove the effects of weather variations, allowing consistent measurement of pollution levels over time and better evaluation of long-term changes.
In the 2010 water year (October 2009-September 2010):
The Bay Program’s goal is to have a long-term average of 186 million pounds of nitrogen and 12.5 million pounds of phosphorus entering the Bay from streams and rivers.
In a different, shorter-term study conducted between 2000 and 2008, the health of individual freshwater streams across the watershed showed mixed conditions. Of the 7,886 stream sites sampled, more than half (55 percent) were found to be in very poor or poor condition. The remaining 45 percent were found to be in fair, good or excellent condition.
This study uses data on the tiny, bottom-dwelling creatures that live in freshwater streams and rivers as an indicator of overall stream health. This method provides a uniform evaluation of the health of local waterways across state lines and throughout the entire Bay watershed.
The USGS estimates how much river flow enters the Bay each year, monitors pollution loads in the Bay’s major rivers, and works with the Bay Program to estimate how much pollution reaches the Bay. To learn more about the USGS’s Chesapeake monitoring activities, visit http://chesapeake.usgs.gov.
What do farms, manure, and a developing technology for creating fertilizer have to do with the Chesapeake Bay? Well, almost one-quarter of the Chesapeake Bay’s 64,000 square mile watershed is agricultural land. Runoff from farmland inevitably drains into the local streams, creeks and rivers that flow to the Chesapeake Bay.
When best management practices are not implemented on agricultural lands, runoff can carry animal waste and excess fertilizer into these waterways, overloading them with nutrients, bacteria and pathogens.
A developing technology called anaerobic digestion has been proposed to reduce phosphorus runoff from many farms. Pilot studies have been conducted in several locations around the world, including at least three Chesapeake Bay watershed states.
Anaerobic digesters, or biodigesters, have become an increasingly popular tool for managing manure on farms. Biodigesters are thought to have several benefits, including reducing farm animal waste runoff, producing nitrogen-rich liquid that can be used as fertilizer, and producing phosphorus-rich solids that can be processed into mulch and other products that would reduce runoff.
Biodigesters are increasing in popularity for use with dairy farms and manure handled as a liquid, slurry or semisolid. However, a Bay Program website visitor wanted to know about the effectiveness of using biodigesters on poultry farms with litter feedstock to improve water quality in the Bay and its tributaries.
One study conducted in the Bay watershed for the Propane Education Research Council tried to determine if this method could decrease the phosphorus in the liquid effluent from the digester exit point. Unfortunately, the study concluded that this was not the case. Phosphorus was only decreased by approximately 5 percent – the same rate of reduction without the anaerobic digestion process. The council concluded that significant phosphorus reduction could be possible if a separate post-digester step was added.
According to that study, the use of biodigesters would not be an effective way for farmers to help improve water quality.
John Ignosh is a scientist with the Virginia Cooperative Extension at Virginia Tech, working on agricultural byproduct utilization. “As far as digesters [used for] litter,” he said, “there have been a few pilot projects looking at this. The main challenge is that digestion is better suited for slurry type feedstocks.”
Most discussion of anaerobic digesters is in reference to digesters using a slurry type feedstock, but Ignosh said there have been pilot projects with litter feed conducted in Maryland, Virginia and West Virginia, among other locations.
An important note is that regardless of the type of feedstock used for the biodigesters, there is not a significant reduction in nutrients from the waste. Nitrogen enters the digester as ammonium and organic nitrogen, and the ammonium is not destroyed in the digester. Instead, the organic nitrogen is converted to ammonium. So the nitrogen in the effluent from the digester typically ends up being higher than when it went in. Similarly, the microorganisms used in the digester do not consume phosphorus. Although some of the phosphorus can be converted to a soluble form, the total mass of phosphorus remains constant.
Therefore, while anaerobic digesters may be useful for producing biogas to create energy and manage waste, they do not reduce the amount of nutrients in the fertilizer or other products it might result in. So fertilizer that is made from a biodigester and is used on farmland would not decrease the amount of nitrogen and phosphorus that would run off the land. These devices also tend to be prohibitively expensive for many farms and do not provide the best benefit for the investment.
For more information, visit the following websites:
A new report by Environment Maryland details the harmful effects of lawn fertilizer on the Chesapeake Bay and explains the steps that should be taken to reduce this pollutant and clean up local waterways.
Lawn fertilizer contains the nutrients nitrogen and phosphorus, which are major sources of pollution in the Bay and its rivers. When homeowners apply too much fertilizer to their lawns, the nutrients can run off into local storm drains when it rains. Excess nutrients can also seep into groundwater, which eventually makes its way into the Bay's streams and rivers.
Turf grass is now the largest crop in Maryland. In 2009, 1.3 million acres were planted with turf, compared with 1.5 million acres for all other crops combined. While farmers are required to develop nutrient management plans and control polluted runoff on their land, there are few rules for homeowners and lawn care companies to follow for fertilizer applications.
The Maryland Department of Agriculture reports that “nonfarm use” of fertilizer is quickly catching up with farm fertilizer sales. Estimates suggest that Maryland landowners apply approximately 86 million pounds of nitrogen fertilizer to their lawns each year. According to the report, researchers monitoring one suburban stream near Baltimore found that 56 percent of the nutrients in the water came from lawn fertilizer.
The report concludes that to reduce pollution for lawn fertilizer, lawmakers need to take two broad steps: limit the amount and type of nutrients in the fertilizer itself, and ensure that homeowners and lawn care companies apply less fertilizer to the ground.
For more information, download the full lawn fertilizer report, “Urban Fertilizers and the Chesapeake Bay: An Opportunity for Major Pollution Reduction.
Virginia is poised to pass a law banning the sale of fertilizer containing phosphorus, a major pollutant in the Chesapeake Bay and its rivers.
Lawns, parks, golf courses and other grass-covered areas cover 3.8 million acres of the Bay watershed. Most established lawns do not need phosphorus, but the majority of commonly used lawn fertilizers include phosphorus in their nutrient mix.
Once it goes into effect in 2013, the law will reduce an estimated 230,000 pounds of phosphorus pollution from reaching the Bay and Virginia rivers each year. This is 22 percent of Virginia's 2017 phosphorus reduction goal.
The law will also:
A variety of groups, including the Chesapeake Bay Foundation, James River Association, Home Builders Association of Virginia and Virginia Association for Commercial Real Estate, supported the legislation.
The legislation was passed by the Virginia Senate and House of Delegates. It now awaits Gov. Bob McDonnell's signature.
When passed, Virginia will become one of nine states that restrict the use or sale of phosphorus in lawn fertilizer. Maryland and Pennsylvania are considering similar legislation.
A new report by the Environmental Working Group finds that phosphorus – a nutrient that leads to algae blooms and low-oxygen “dead zones” in the Chesapeake Bay – is saturating the soil of farmland in many parts of the Bay watershed.
The report, Bay Out of Balance, finds that in 20 percent of the counties in the Bay watershed, more than half of the soil tested contained far more phosphorus than crops can use. Once soil is overloaded with phosphorus, the nutrient becomes a pollutant that can persist for many years.
Farmers apply phosphorus-rich manure and fertilizer to their land to help crops grow. Research in the report shows that fertilizer is being applied to soil that already has enough nutrients to meet plants’ needs. About 45 percent of the phosphorus that reaches the Bay comes from agriculture.
“One of most important things we can do to clean up Chesapeake Bay is ensure that farms add only the phosphorus that plants need to thrive,” said Rebecca Sutton, Ph.D., lead author of the report. We need to regard phosphorus as a potential pollutant, ensure that farmers don’t over-fertilize and find non-polluting ways to dispose of excess manure.”
The report lists three recommendations for the states to monitor and reduce the amount of phosphorus that is applied to the Bay watershed’s farmland:
Visit the Environmental Working Group’s website to read the full report.
The new analysis reveals mixed news about progress toward reducing nutrients over the past 31 years, particularly during the last decade.
Since 2000, nitrogen has been decreasing in the Susquehanna and Potomac rivers, while levels are nearly unchanged in the James and Rappahannock rivers. During the same period, phosphorus levels changed minimally in the Susquehanna, while there were moderate decreases in the Potomac and measurable increases and the James and Rappahannock.
Looking back even farther, scientists found a substantial improvement in pollution loads from the Patuxent River since 1978. Phosphorus from the Patuxent declined by 75 percent from 1978-2000, while nitrogen declined by about 26 percent during the same time period and an additional 15 percent from 2000-2008. These improvements are likely due to large investments in advanced wastewater treatment facilities.
Conversely, there was a 53 percent increase in nitrogen from the Choptank River from 1978-2008. Much of the increase is attributed to groundwater flowing into the river from deep below the land surrounding the river.
The new method takes multiple factors into consideration: seasonality, variations in river flow, and long-term trends driven by human activities, such as wastewater treatment and land management.
“When we analyze long-term nutrient trends for the Chesapeake Bay or other major water systems, it’s important that we consider [river] flow variations,” said Robert Hirsch, a USGS research hydrologist who led the development of the new method. “This new method enables us to remove this source of variation from the data and get a much clearer picture of the effect of human activities, including nutrient-management actions, on nutrient delivery from these watersheds to the Bay.”
Methods that do not consider variations in river flow can paint a much different picture of long-term nutrient trends in the Bay.
For example, 1999-2002 were very dry years throughout the Bay watershed. As a result, nutrient delivery to the Bay was relatively low and conditions in the Bay appeared to be much improved.
These years were followed by extremely high flow conditions in 2003, and then a series of progressively drier years from 2004 through 2008. The 2003 data showed very poor conditions, but the subsequent years’ data suggest slow improvements from one year to the next.
“These apparent changes were largely the consequence of differences in flow,” said Hirsch. “This new method helps us to see past these random year-to-year changes and get at the underlying long-term changes taking place.”
“The new USGS method will allow the Chesapeake Bay partners to better assess progress toward reducing the delivery of nutrients and sediment to the Chesapeake Bay,” said Rich Batiuk, the Chesapeake Bay Program’s associate director for science. “This method, based on monitoring data, will improve accountability regarding the nutrient reductions needed to meet our restoration goals for the Bay.”
USGS, a Chesapeake Bay Program partner, works with other partners to collect data for the Bay Program’s Nontidal Water Quality Network and provides critical science to the Bay Program partnership. Learn more about USGS Chesapeake Bay activities at http://chesapeake.usgs.gov.
The new analysis is available online in a report from the Journal of the American Water Resources Association.
Welcome to this week’s installment of the BayBlog Question of the Week! Each week we'll take a question submitted through the Chesapeake Bay Program website and answer it here for all to read.
This week, Dave is trying to get a sense of “who is causing what” in relation to the Chesapeake Bay’s pollution issues. He wants to know: what are the main sources of nitrogen, phosphorous and sediment to the Bay?
It’s important to know where Chesapeake Bay pollution comes from because we can use that knowledge to do our part to reduce the amount of pollutants each of us contributes to the Bay and its local waterways.
Nitrogen occurs naturally in soil, animal waste, plant material and the atmosphere. However, most of the nitrogen delivered to the Bay comes from:
Phosphorous, like nitrogen, occurs naturally in soil, animal waste and plant material. But these natural sources account for just 3 percent of the phosphorous loads to the Chesapeake Bay. Here are the major sources of the Bay’s phosphorus pollution:
Sediments are loose particles of clay, silt and sand. When suspended in the water, sediment can block sunlight from reaching underwater bay grasses. As sediment settles to the bottom of the Bay and its rivers, it smothers bottom-dwelling animals (such as oysters). Sediment can also carry high concentrations of phosphorus and toxic chemicals.
Most of the sediment to the Bay comes from agriculture. Natural sources, stormwater runoff and erosion from streams make up the rest of the sources of sediment to the Bay and its local waterways.
While some sources of pollution may be larger than others, one source is not more important to prevent than any other. We must take any and all steps to reduce nitrogen, phosphorous and sediment loads to the Bay. Think about how your daily actions contribute pollution to the Bay and its rivers. Be sure to check out our Help the Bay tips to learn how you can do your part.