Summarizing Science to Inform Management in the Chesapeake Bay Watershed
Priority Stakeholder Questions
Summarizing Scientific Insights to Inform Nutrient and Sediment Management Activities in the Chesapeake Bay Watershed
Stakeholders can use scientific insights to address their priority water-quality concerns. The USGS works with Chesapeake Bay stakeholders to identify and address priority questions that can help inform management decisions. These scientific insights can help guide nutrient and sediment management activities undertaken by Chesapeake Bay stakeholders.
This webpage summarizes recent scientific insights about some priority questions being asked throughout the Chesapeake Bay watershed. Here, you can learn more about these findings and their management implications.
Priority Stakeholder Questions
Although the most pressing water-quality concerns may be different in various regions of the Chesapeake Bay watershed, stakeholders often have similar questions. Answering these questions and providing our stakeholders with the best available data can help inform the management of nutrients and sediment.
These nine Priority Stakeholder Questions were identified by our community of stakeholders, and scientific insights that can help answer these questions and guide management decisions are summarized below.
Capabilities
How can stakeholders use modeling and monitoring to strengthen decision-making?
How has the amount of nutrients and sediment changed over time in Chesapeake Bay streams and rivers?
What drives nutrient responses in Chesapeake Bay streams and rivers?
What are the characteristics of effective nutrient and sediment management practices?
How do legacy nutrients affect recent changes in nitrogen and phosphorus?
How does the water quality of streams and rivers affect conditions in the Chesapeake Bay?
How does improving water quality benefit biological communities and human health?
How can different sediment sources reach streams and be managed?
How do temperature and rainfall changes affect water quality responses and management practice effects?
Learn More
How can stakeholders use modeling and monitoring to strengthen decision-making?
Summary: Models help us plan for the future, while monitoring allows us to measure our effectiveness. These resources have different strengths and applications, but both are needed to plan and evaluate effective management strategies.
Management Implications:
- Stakeholders can use modeling tools to plan nutrient and sediment reduction activities and forecast their possible effects.
- The Chesapeake Assessment Scenario Tool (CAST) is a free, online nitrogen, phosphorus and sediment load estimator tool that streamlines environmental planning. Learn how to use CAST here.
- While models can predict possible outcomes, only monitoring data can tell us if water quality conditions are improving. Monitoring data offer an accurate assessment of how water-quality conditions are changing over time.
- The Nontidal Monitoring Network uses water-quality and streamflow observations to measure nitrogen, phosphorus, and sediment conditions at 123 streams and rivers throughout the Chesapeake Bay Watershed.
How has the amount of nutrients and sediment changed over time in Chesapeake Bay streams and rivers?
Summary: Water-quality samples and streamflow measurements are collected from 123 monitoring stations that make up the Nontidal Monitoring Network. These data are used to evaluate the amount of nitrogen, phosphorus, and sediment in the nontidal rivers and streams of the Chesapeake Bay watershed. These amounts, referred to as loads, are calculated at individual monitoring stations. After removing the effect of year-to-year differences in streamflow, trends in load are also calculated, which represent the change in load over multiple years. Nutrient and sediment trends can help determine if water-quality conditions are getting better or worse throughout the watershed.
Management Implications:
- Trends in nutrient and sediment load differ throughout the watershed: loads have decreased at some stations but increased at others.
- Total nitrogen loads decreased at 38% of stations.
- Total phosphorus loads decreased at 44% of stations.
- Suspended sediment loads decreased at 17% of stations.
- Most nutrient and sediment loads reach streams during high streamflow conditions. Management strategies that control the movement of nutrient and sediment loads during high-flow events could help reduce loads.
What drives nutrient responses in Chesapeake Bay streams and rivers?
Summary: A complex mix of factors affect how nutrients change over time in nontidal streams and rivers. These factors include human activities (such as urban development, point and nonpoint source nutrient inputs, and management practices) and natural conditions (such as rainfall, temperature, and streamflow). Understanding the specific effects of these factors can help guide effective management strategies.
Management Implications:
- Point source reductions, mostly because of wastewater treatment plant upgrades, are responsible for substantial nutrient reductions throughout the Chesapeake Bay watershed. Additionally, air-quality improvements have helped reduce nitrogen loads.
- Agricultural nonpoint sources of manure and fertilizer contribute large amounts of nutrients to the Bay. Total manure and fertilizer inputs to the Bay watershed have remained steady over the last several decades but have varied in some local watersheds. In many agricultural watersheds, water-quality loads may not improve until these nutrient inputs are lowered to align with local crop demand.
- Urban areas are expanding throughout the Bay watershed which can introduce new nutrient inputs.
- Studies have shown that management practices can reduce nutrient loads. However, these reductions are often found in small study areas and are not always observed in larger watersheds. In some watersheds, increasing nutrient inputs may offset expected management-practice benefits. Researchers and managers are working together to learn more about the water-quality effects of management practices.
What are the characteristics of effective nutrient and sediment management practices?
Summary: Many different management practices can be used to reduce nutrient and sediment loads, but the effectiveness of different management practices can vary based on local watershed settings.
Management Implications:
- Management practices that lower the amount of nutrients applied to the landscape are generally more effective than management practices that try to prevent the movement of nutrients from the landscape to streams.
- Effective management practices address the largest nutrient and sediment sources in a watershed.
- Manure and fertilizer can be the largest nutrient sources in agricultural watersheds.
- Wastewater and fertilizer can be the largest nutrient sources in urban watersheds.
- Streambank erosion can be a large sediment source in small streams. Upland erosion can be a large sediment source in rivers.
- The effectiveness of management practices might be improved by the targeted use of multiple management practices in areas of the watershed with large nutrient and sediment loads.
How do legacy nutrients affect recent changes in nitrogen and phosphorus?
Summary: Legacy nutrients are nutrients that were applied to the watershed in previous years and are now stored in the soil or groundwater. Legacy nutrients can enter a stream long after they were originally applied and can affect recent water-quality changes.
Management Implications:
- Legacy nutrients are typically higher in areas of the watershed with surplus nutrient inputs. Surplus inputs occur when nutrient applications exceed the amount of nutrients needed by crops and other vegetation.
- In agricultural watersheds, aligning the amount of nutrients applied from manure and fertilizer with the amount of nutrients needed by crops can help prevent the accumulation of legacy nutrients.
- While chemical processes can remove nitrogen from a watershed, there are no natural processes that remove phosphorus once it is applied. Even if surplus phosphorus inputs are reduced, it may take years or decades for legacy soil phosphorus concentrations to decline.
- Legacy nutrients can delay expected water-quality improvements. These delays, referred to as lag times, differ throughout the watershed based on land activities and geologic settings.
How does the water quality of streams and rivers affect conditions in the Chesapeake Bay?
Summary: Amounts of nutrients, dissolved oxygen, and submerged aquatic vegetation in the Bay are affected by many factors, including the quality of water delivered by watershed streams and rivers.
Management Implications:
- Water-quality conditions in the Bay show the impacts of and recovery from extreme weather events. In general, water-quality conditions are worse when more freshwater flow enters the Bay.
- Nutrients and sediment delivered from watershed streams and rivers impacts water-quality in the Bay. These effects can vary seasonally and spatially throughout the Bay.
How does improving water quality benefit biological communities and human health?
Summary: Nutrients and sediment are needed to support healthy biological communities but, in excess, can be harmful. Excess nutrients, sediment, and associated pollutants can also be harmful to humans. Therefore, nutrient and sediment management activities can also address many local water-quality concerns.
Management Implications:
- Many management practices that are designed to reduce nutrients and sediment may also benefit fish habitat and health. Nutrient and sediment reductions can also protect human health by providing safe drinking water, reducing the occurrence of toxic contaminants, and the presence of harmful algal blooms.
- Local groups, county governments, and state agencies can partner with the USGS to expand the use of monitoring to address local water-quality priorities.
How can different sediment sources reach streams and be managed?
Summary: Sediment reaches streams through erosion of streambanks, resuspension of in-channel material, or runoff from upland areas. Recent and legacy sediment sources can be delivered to streams from these different pathways.
Management Implications:
- Legacy sediment refers to sediment that accumulated in stream floodplains or channels during the 17th to 19th centuries when Europeans colonized the Eastern United States and disturbed the landscape. Reducing the delivery of legacy sediment to streams may be important to meet water-quality goals.
- Agricultural and urban lands contribute large amounts of sediment to the Bay and are important areas for sediment management activities.
- The way sediment reaches streams is an important consideration for managing sediment. Practices that control streambank erosion can be useful in small streams. Practices that conserve and restore floodplains can be important in larger rivers.
- In the Lower Susquehanna River, more sediment is being delivered to the Bay because of sediment infill of the Conowingo Reservoir. Understanding the water-quality effects of reservoirs on the Lower Susquehanna River is critical to managing the health of the Bay.
How do temperature and rainfall changes affect water-quality responses and management practice effects?
Summary: Changing weather patterns can have complex effects on streamflow and water-quality. Rainfall differs seasonally, with droughts in some years and floods in others. Recent years have generally been warmer and wetter. In general, water temperature is expected to increase, along with precipitation volume and intensity of precipitation events.
Management Implications:
- Wetter years can produce more streamflow that carries more nutrients and sediment to streams. It may be more challenging to meet water-quality goals in wetter years.
- Warmer and wetter years can change the amount of nutrients stored in soils, removed by plants, or needed for agriculture. These changes may increase or decrease the amount of nutrients in streams.
- Future climatic conditions are important to consider when planning effective management strategies. Changes in rainfall and temperature can alter the effectiveness of some management practices, particularly those that reduce nutrients and sediment by controlling streamflow.
Interested in learning more?
Our interactive pdf is a great place to dig deeper into specific findings for each of these nine topics and their management implications.
Stakeholders can use scientific insights to address their priority water-quality concerns. The USGS works with Chesapeake Bay stakeholders to identify and address priority questions that can help inform management decisions. These scientific insights can help guide nutrient and sediment management activities undertaken by Chesapeake Bay stakeholders.
This webpage summarizes recent scientific insights about some priority questions being asked throughout the Chesapeake Bay watershed. Here, you can learn more about these findings and their management implications.
Priority Stakeholder Questions
Although the most pressing water-quality concerns may be different in various regions of the Chesapeake Bay watershed, stakeholders often have similar questions. Answering these questions and providing our stakeholders with the best available data can help inform the management of nutrients and sediment.
These nine Priority Stakeholder Questions were identified by our community of stakeholders, and scientific insights that can help answer these questions and guide management decisions are summarized below.
Capabilities
How can stakeholders use modeling and monitoring to strengthen decision-making?
How has the amount of nutrients and sediment changed over time in Chesapeake Bay streams and rivers?
What drives nutrient responses in Chesapeake Bay streams and rivers?
What are the characteristics of effective nutrient and sediment management practices?
How do legacy nutrients affect recent changes in nitrogen and phosphorus?
How does the water quality of streams and rivers affect conditions in the Chesapeake Bay?
How does improving water quality benefit biological communities and human health?
How can different sediment sources reach streams and be managed?
How do temperature and rainfall changes affect water quality responses and management practice effects?
Learn More
How can stakeholders use modeling and monitoring to strengthen decision-making?
Summary: Models help us plan for the future, while monitoring allows us to measure our effectiveness. These resources have different strengths and applications, but both are needed to plan and evaluate effective management strategies.
Management Implications:
- Stakeholders can use modeling tools to plan nutrient and sediment reduction activities and forecast their possible effects.
- The Chesapeake Assessment Scenario Tool (CAST) is a free, online nitrogen, phosphorus and sediment load estimator tool that streamlines environmental planning. Learn how to use CAST here.
- While models can predict possible outcomes, only monitoring data can tell us if water quality conditions are improving. Monitoring data offer an accurate assessment of how water-quality conditions are changing over time.
- The Nontidal Monitoring Network uses water-quality and streamflow observations to measure nitrogen, phosphorus, and sediment conditions at 123 streams and rivers throughout the Chesapeake Bay Watershed.
How has the amount of nutrients and sediment changed over time in Chesapeake Bay streams and rivers?
Summary: Water-quality samples and streamflow measurements are collected from 123 monitoring stations that make up the Nontidal Monitoring Network. These data are used to evaluate the amount of nitrogen, phosphorus, and sediment in the nontidal rivers and streams of the Chesapeake Bay watershed. These amounts, referred to as loads, are calculated at individual monitoring stations. After removing the effect of year-to-year differences in streamflow, trends in load are also calculated, which represent the change in load over multiple years. Nutrient and sediment trends can help determine if water-quality conditions are getting better or worse throughout the watershed.
Management Implications:
- Trends in nutrient and sediment load differ throughout the watershed: loads have decreased at some stations but increased at others.
- Total nitrogen loads decreased at 38% of stations.
- Total phosphorus loads decreased at 44% of stations.
- Suspended sediment loads decreased at 17% of stations.
- Most nutrient and sediment loads reach streams during high streamflow conditions. Management strategies that control the movement of nutrient and sediment loads during high-flow events could help reduce loads.
What drives nutrient responses in Chesapeake Bay streams and rivers?
Summary: A complex mix of factors affect how nutrients change over time in nontidal streams and rivers. These factors include human activities (such as urban development, point and nonpoint source nutrient inputs, and management practices) and natural conditions (such as rainfall, temperature, and streamflow). Understanding the specific effects of these factors can help guide effective management strategies.
Management Implications:
- Point source reductions, mostly because of wastewater treatment plant upgrades, are responsible for substantial nutrient reductions throughout the Chesapeake Bay watershed. Additionally, air-quality improvements have helped reduce nitrogen loads.
- Agricultural nonpoint sources of manure and fertilizer contribute large amounts of nutrients to the Bay. Total manure and fertilizer inputs to the Bay watershed have remained steady over the last several decades but have varied in some local watersheds. In many agricultural watersheds, water-quality loads may not improve until these nutrient inputs are lowered to align with local crop demand.
- Urban areas are expanding throughout the Bay watershed which can introduce new nutrient inputs.
- Studies have shown that management practices can reduce nutrient loads. However, these reductions are often found in small study areas and are not always observed in larger watersheds. In some watersheds, increasing nutrient inputs may offset expected management-practice benefits. Researchers and managers are working together to learn more about the water-quality effects of management practices.
What are the characteristics of effective nutrient and sediment management practices?
Summary: Many different management practices can be used to reduce nutrient and sediment loads, but the effectiveness of different management practices can vary based on local watershed settings.
Management Implications:
- Management practices that lower the amount of nutrients applied to the landscape are generally more effective than management practices that try to prevent the movement of nutrients from the landscape to streams.
- Effective management practices address the largest nutrient and sediment sources in a watershed.
- Manure and fertilizer can be the largest nutrient sources in agricultural watersheds.
- Wastewater and fertilizer can be the largest nutrient sources in urban watersheds.
- Streambank erosion can be a large sediment source in small streams. Upland erosion can be a large sediment source in rivers.
- The effectiveness of management practices might be improved by the targeted use of multiple management practices in areas of the watershed with large nutrient and sediment loads.
How do legacy nutrients affect recent changes in nitrogen and phosphorus?
Summary: Legacy nutrients are nutrients that were applied to the watershed in previous years and are now stored in the soil or groundwater. Legacy nutrients can enter a stream long after they were originally applied and can affect recent water-quality changes.
Management Implications:
- Legacy nutrients are typically higher in areas of the watershed with surplus nutrient inputs. Surplus inputs occur when nutrient applications exceed the amount of nutrients needed by crops and other vegetation.
- In agricultural watersheds, aligning the amount of nutrients applied from manure and fertilizer with the amount of nutrients needed by crops can help prevent the accumulation of legacy nutrients.
- While chemical processes can remove nitrogen from a watershed, there are no natural processes that remove phosphorus once it is applied. Even if surplus phosphorus inputs are reduced, it may take years or decades for legacy soil phosphorus concentrations to decline.
- Legacy nutrients can delay expected water-quality improvements. These delays, referred to as lag times, differ throughout the watershed based on land activities and geologic settings.
How does the water quality of streams and rivers affect conditions in the Chesapeake Bay?
Summary: Amounts of nutrients, dissolved oxygen, and submerged aquatic vegetation in the Bay are affected by many factors, including the quality of water delivered by watershed streams and rivers.
Management Implications:
- Water-quality conditions in the Bay show the impacts of and recovery from extreme weather events. In general, water-quality conditions are worse when more freshwater flow enters the Bay.
- Nutrients and sediment delivered from watershed streams and rivers impacts water-quality in the Bay. These effects can vary seasonally and spatially throughout the Bay.
How does improving water quality benefit biological communities and human health?
Summary: Nutrients and sediment are needed to support healthy biological communities but, in excess, can be harmful. Excess nutrients, sediment, and associated pollutants can also be harmful to humans. Therefore, nutrient and sediment management activities can also address many local water-quality concerns.
Management Implications:
- Many management practices that are designed to reduce nutrients and sediment may also benefit fish habitat and health. Nutrient and sediment reductions can also protect human health by providing safe drinking water, reducing the occurrence of toxic contaminants, and the presence of harmful algal blooms.
- Local groups, county governments, and state agencies can partner with the USGS to expand the use of monitoring to address local water-quality priorities.
How can different sediment sources reach streams and be managed?
Summary: Sediment reaches streams through erosion of streambanks, resuspension of in-channel material, or runoff from upland areas. Recent and legacy sediment sources can be delivered to streams from these different pathways.
Management Implications:
- Legacy sediment refers to sediment that accumulated in stream floodplains or channels during the 17th to 19th centuries when Europeans colonized the Eastern United States and disturbed the landscape. Reducing the delivery of legacy sediment to streams may be important to meet water-quality goals.
- Agricultural and urban lands contribute large amounts of sediment to the Bay and are important areas for sediment management activities.
- The way sediment reaches streams is an important consideration for managing sediment. Practices that control streambank erosion can be useful in small streams. Practices that conserve and restore floodplains can be important in larger rivers.
- In the Lower Susquehanna River, more sediment is being delivered to the Bay because of sediment infill of the Conowingo Reservoir. Understanding the water-quality effects of reservoirs on the Lower Susquehanna River is critical to managing the health of the Bay.
How do temperature and rainfall changes affect water-quality responses and management practice effects?
Summary: Changing weather patterns can have complex effects on streamflow and water-quality. Rainfall differs seasonally, with droughts in some years and floods in others. Recent years have generally been warmer and wetter. In general, water temperature is expected to increase, along with precipitation volume and intensity of precipitation events.
Management Implications:
- Wetter years can produce more streamflow that carries more nutrients and sediment to streams. It may be more challenging to meet water-quality goals in wetter years.
- Warmer and wetter years can change the amount of nutrients stored in soils, removed by plants, or needed for agriculture. These changes may increase or decrease the amount of nutrients in streams.
- Future climatic conditions are important to consider when planning effective management strategies. Changes in rainfall and temperature can alter the effectiveness of some management practices, particularly those that reduce nutrients and sediment by controlling streamflow.
Interested in learning more?
Our interactive pdf is a great place to dig deeper into specific findings for each of these nine topics and their management implications.