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:
The National Research Council of the National Academy of Sciences (NAS) has released a pilot study that contains science-based conclusions and recommendations to help the Chesapeake Bay Program evaluate its efforts to achieve nutrient reduction goals and clean up the Bay.
The study, “Achieving Nutrient and Sediment Reduction Goals in the Chesapeake Bay: An Evaluation of Program Strategies and Implementation,” validates and provides constructive feedback on the work the Bay Program has undertaken during the last 18 months to improve accountability.
“While supporting the program’s current efforts, the report also points out some critical challenges to consider in making decisions moving forward,” said Shawn M. Garvin, EPA regional administrator and chair of the Bay Program’s Principals' Staff Committee.
The NAS study results reinforce the partnership’s current work, including the Chesapeake Bay “pollution diet,” or TMDL; the Bay jurisdictions’ Watershed Implementation Plans (WIPs); and two-year milestones. NAS recognized the Bay watershed’s complexity and the equally intricate tracking systems needed to accurately report on restoration progress, as well as the fact that the Bay Program is in the process of better integrating its voluntary and regulatory work.
The study also provides suggestions for strengthening processes for tracking and accounting of best management practices (BMPs); assessing two-year milestones; adaptive management; and implementation strategies.
“As the states continue to clean up the Chesapeake Bay, we must regularly review and take steps to improve the management of our resources to achieve the most cost-effective results for our citizens and the Bay," said Maryland Department of the Environment Secretary Robert M. Summers. “We believe a healthy Chesapeake Bay is finally within our sights, and we look forward to working with our partners to determine how the Academy's recommendations can help.”
Within 90 days, the Bay Program will provide a written response to all of the study’s recommendations.
The Bay Program solicited this self-evaluation in 2009 after the Chesapeake Executive Council requested at its 2008 annual meeting that a nationally recognized, independent science organization evaluate the program’s efforts to accelerate implementation of nutrient reduction goals to restore the Bay.
The evaluation was jointly funded by the U.S. Environmental Protection Agency Chesapeake Bay Program, Maryland, Pennsylvania, Virginia and the District of Columbia.
To be honest, I was kicking myself a little bit after our latest photo trip. I realized how dumb I have been for not visiting Patapsco Valley State Park in the one and a half years I've lived here.
When living in an urban environment, you sometimes forget what clean, fresh air feels like. I definitely felt healthier the day of the trip, being surrounded by so many trees and other living things.
I wasn't the only one trying to get out and enjoy the nice weather. We saw a number of hikers, bikers, fisherman and families taking to the trails. The park has multiple waterfalls, picnic areas, and plenty of walkways to check out.
I would strongly recommend visiting Patapsco Valley State Park if you live nearby. They are actually having a volunteer fair this Saturday (May 7th) from 10-1. According to the Maryland Department of Natural Resources website, you will be able to “Explore all the volunteer opportunities available including volunteer rangers, photographers, camp hosts, trail workers, naturalists and much more!”
We want to hear from you! What are your favorite Chesapeake Bay-region parks to visit when the weather is nice?