Nitrogen

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Chesapeake Bay Program Indicator Framework

Reporting Level Indicators

Indicator and Data Survey

(Note:  Survey for river flow indicator begins on page 8.)

Metadata

A.  Category/Name/Source/Contact

(1) Category of Indicator

_x_ Factors Impacting Bay and Watershed Health

___ Restoration and Protection Efforts

___ Watershed Health

___ Bay Health

(2) Name of Indicator: Chesapeake Bay watershed nitrogen, phosphorus, and suspended sediment load indicators

(3) Data Set Description:  

For what purpose(s) were the data collected? (e.g., tracking, research, or long-term monitoring.) -  Long-term monitoring.

Which parameters were measured directly? Discharge, nitrogen, suspended sediment and phosphorus concentrations at the river input sites. Point-source discharges were reported to EPA. Total delivered suspended sediment loads are estimated using only RIM monitoring data.

Which were obtained by calculation? Loads at the river input stations were estimated with a statistical model using observed flow and concentration data. Loads were calculated as the product of concentration and flow.  Point source loads (i.e., delivered to the Bay) were estimated from EPA discharge monitoring (end-of-pipe) adjusted by delivery factors used in the CPBO HSPF watershed model. Load contributions from unmonitored areas (i.e., below fall-line) were calculated by scaling observed river input loads using information from the CBPO HSPF watershed model (using load estimates for modeled scenarios for 1985, 2002, and 2003). RIM load estimates for 2009 were made by USGS using the ESTIMATOR statistical model that relates concentration to flow and then uses daily estimated flows to determine loads (one model fit to entire period of record, not the standard method of shifting 9-year window of data). No data for 2009 water-year below the fall-line point and non-point-source loads were available due to data reporting lag, so contributions were estimated by using the 2008 load value.  

(4) Source(s) of Data: USGS, EPA, and CBPO

Is the complete data set accessible, including metadata, data-dictionaries and embedded definitions? If yes, please indicate where complete dataset can be obtained. USGS River input data (http://va.water.usgs.gov/chesbay/RIMP/index.html), point-source loads (http://www.chesapeakebay.net/data/index.htm), point-source delivery factors (CBP watershed model phase 4.3), and CBP HSPF Phase 4.3 watershed model load estimates (http://www.chesapeakebay.net/data/index.htm).

(5) Custodian of Source Data (and Indicator, if different): River input data – Joel Blomquist (USGS 443-498-5500), Watershed model scenario runs - Jeff Sweeney (Univ. Maryland CBPO 800-YOUR-BAY ext 844), Point source loads - Ning Zhou (Virginia Tech/CBPO 800-YOUR-BAY ext 727), watershed load calculations and synthesis – Katie Foreman (Univ. Maryland/CBPO 800-YOUR-BAY ext 837).

(6) CBPO Contact: Katie Foreman (800-YOUR-BAY ext 837)

B.  Communication Questions

(complete either part 1, 2, or 3)

3.  Factors Impacting Bay and Watershed Health indicators only

(7c) What is the long-term trend?  (since start of data collection  1990 was the first year where all necessary data were available)

Rigorous statistical analyses to determine trends in loads have not been developed at this time. The amount of nutrients delivered to the Bay from the watershed changes dramatically from year-to-year complicating efforts to determine trends through time.

(8c) What is the short-term trend? (10-year trend)

The last 10 years have highly variable nitrogen and phosphorus loads with 1999-2002 being very low load years followed by two much higher load years followed by lower loading years to the present. 

(9c) What is the current status?

Provisional estimates indicate that approximately 240 million pounds of nitrogen reached the Bay during the 2009 water year, which is below the average load for 1990-2009 of 338 million pounds.  Additionally, provisional estimates indicate that approximately 11.3 million pounds of phosphorus reached the Bay during the 2009 water year, which is below the 1990-2009 load average of 20.8 million pounds. Also, preliminary results  indicate that 2.0 million tons of sediment reached the Bay during 2009, which is below the 1990-2009 load average of 4 million tons.   Values are above or very close to the targets for nitrogen and phosphorus (respectively) put forth by the EPA.  These load targets are based on modeled scenarios that meet water quality criteria (US EPA 2003).

(10c) What does this indicator tell us?

Watershed-derived nitrogen is commonly delivered by rivers and groundwater to the Bay, whereas phosphorus is typically attached to particles and delivery is elevated during storm-related discharge events. For both constituents, the total amount transported to the Bay is largely determined by river flow.  In 2009, river flows were below the long term average which helped influence nitrogen and phosphorus loads to be below long term loading averages as well during that year. 

(11c) Why is it important to report this information?

Aquatic plants and animals rely on nitrogen and phosphorus for cellular processes involved with growth and development. When excessive nutrients reach the Bay, they alter the balance among organisms. Nitrogen often limits algal growth in the saltier waters of the Bay, whereas phosphorus stimulates plants and algae in the freshwater portions of the Bay’s tributaries. High nutrient loads early in the spring can facilitate the growth of algae and can result in hypoxia and anoxia (very low dissolved oxygen concentrations) in the deeper areas of the Bay. Elevated nutrient loads degrade water quality and are therefore targeted for load reductions. 

(12c) What detail and/or diagnostic indicators are related to this reporting level indicator?

Diagnostic indicators for nutrient and sediment loads have three load components. These figures show the summation of these components estimated from (1) river input monitoring sites, (2) tidal point sources, and (3) tidal nonpoint sources.

C.  Temporal Considerations

(13) Data Collection Date(s): Water year (October 1-September 30) 1990-2009

(14) Planned Update Frequency (e.g. - annual, bi-annual):

(a) Source Data:

a.River input data - annual

b.Watershed model scenario runs – infrequent (annual) – usually one-year delay

c.Point source loads – annual, usually one-year delay

(b) Indicator: Annual

(15) For annual reporting, month spatial data is available for reporting: Data are typically analyzed by the USGS for river input monitoring program by April of each year. Efforts are underway to shorten the delivery time to February. Point source data and modeled data will not be available in a timely manner and, therefore, estimated values will need to be used in the calculations.

D.  Spatial Considerations

(16) Type of Geography of Source Data (point, line polygon, other): N.A.

(17) Acceptable Level of Spatial Aggregation (e.g. - county, state, major basin, tributary basin, HUC):

Entire watershed

(18) Are there geographic areas with missing data?  If so, where?

The estimates do not include inputs from the ocean, direct atmospheric deposition to the Bay, or shoreline erosion.

(19) The spatial extent of this indicator best described as:

(a) Chesapeake Bay (estuary)

(b) Chesapeake Bay Watershed

(c) Other (please describe): _______________________

Please submit any appropriate examples of how this information has been mapped or otherwise portrayed geographically in the past.

Data for river input monitoring and point sources are spatially explicit, however these data are combined to make a watershed-wide estimate of loads from unmonitored areas in the coastal plain (i.e., tidal nonpoint sources). The nontidal water-quality workgroup plans to determine the feasibility of making this indicator spatially explicit in the future.

(20) Can appropriate diagnostic indicators be represented geographically?

Yes, however currently no spatially explicit diagnostic indicators for loads exist.

E.  Data Analysis and Interpretation

(Please provide appropriate references and location of documentation if hard to find.)

(21) Is the conceptual model used to transform these measurements into an indicator widely accepted as a scientifically sound representation of the phenomenon it indicates?  (i.e., how well do the data represent the phenomenon?)  

The methods for making these calculations have been reviewed internally at the Chesapeake Bay program (viz., the Nontidal Water-quality Workgroup). Portions of the data used in this indicator, such as the river input monitoring load estimates, have also passed the external peer-review process required during publication in scientific journals. A scientific manuscript documenting the methods used to estimate fluvial loads will be submitted for external peer-review at a scientific journal.  

(22) What is the process by which the raw data is summarized for development and presentation of the indicator?   

Refer to USGS’s website for river input monitoring loads (http://va.water.usgs.gov/chesbay/RIMP/methods.html) CBP’s documentation of point source loads (http://www.chesapeakebay.net/pubs/114.pdf), delivery factors used to estimate delivered point source loads to the Bay (CBP HSPF watershed model phase 4.3).

(23) Are any tools required to generate the indicator data (e.g. - Interpolator, watershed model)

USGS LOADEST (Runkel et al. 2004)

(24) Are the computations widely accepted as a scientifically sound? 

(25) Have appropriate statistical methods been used to generalize or portray data beyond the time or spatial locations where measurements were made (e.g., statistical survey inference, no generalization is possible)? 

Every effort was made to minimize extrapolations beyond the available data. The only exception would be for unavailable 2009 point and non-point source data. (see 34)

(26) Are there established reference points, thresholds or ranges of values for this indicator that unambiguously reflect the desired state of the environment? (health/stressors only) 

CBP has set a long-term (10 year) average load target Chesapeake Bay for nitrogen and phosphorus at 175 and 12.8 million lbs per year, respectively. These load targets are based on modeled scenarios that meet water quality criteria (US EPA 2003). Direct comparisons of these targets to loads from individual years should be avoided since individual years are not directly comparable to modeled, average load conditions.

F.  Data Quality

(Please provide appropriate references and location of documentation if hard to find.)

(27) Were the data collected according to an EPA-approved Quality Assurance Plan?  

If no, complete questions 28a – 28d:

No

(28a) Are the sampling design, monitoring plan and/or tracking system used to collect the data over time and space based on sound scientific principles?

Yes

(28b) What documentation clearly and completely describes the underlying sampling and analytical procedures used?  

USGS river input monitoring-(Langland et al. 2005), U.S. EPA point source-http://www.chesapeakebay.net/pubs/114.pdf) and watershed modeling (Linker et al. 2000).

(28c) Are the sampling and analytical procedures widely accepted as scientifically and technically valid? 

Yes.  Most procedures are published in peer-reviewed or government publications. USGS river input monitoring-(Langland et al. 2005), U.S. EPA point source-http://www.chesapeakebay.net/pubs/114.pdf) and watershed modeling (Linker et al. 2000).

(28d) To what extent are the procedures for quality assurance and quality control of the data documented and accessible?

Each data provider has quality assurance protocols that they implement to ensure that high quality data are available for analysis. USGS river input monitoring VA (Moyer 2005) and MD (Tenbus 2006). U.S. EPA point source-http://www.chesapeakebay.net/pubs/114.pdf).

(29) Are the descriptions of the study or survey design clear, complete and sufficient to enable the study or survey to be reproduced?  

Forthcoming documents will describe the calculations in more detail.

(30) Were the sampling and analysis methods performed consistently throughout the data record?

No, water year 2009 used a different statistical model period.

(31) If datasets from two or more agencies are merged, are their sampling designs and methods comparable?

Yes

(32) Are uncertainty measurements or estimates available for the indicator and/or the underlying data set?

No, additional work on estimates is needed to more accurately assess uncertainty. Information regarding the statistical uncertainty for the river input monitoring loads does exist at http://va.water.usgs.gov/chesbay/RIMP/loads.html.

(33) (Do the uncertainty and variability impact the conclusions that can be inferred from the data and the utility of the indicator?

High uncertainly in the load estimates would make it difficult to assess status and trends as the estimate of the loads could range widely. This indicator’s uncertainty has not been fully assessed so generalizations regarding the utility of this indicator cannot be made with confidence.

(34) Are there noteworthy limitations or gaps in the data record?  Please explain.

No data for 2009 water-year below the fall-line non-point-source loads and 2009 point source were not available due to data reporting lag, so contributions were estimated by using the 2008 load value for both constituents.

G.  Additional Information

(optional)

(35) Please provide any other information about this indicator you believe is necessary to aid communication and any prevent potential miss-representation.

1.Loads that were estimated for the Below Fall Line areas (tidal nonpoint source loads) should be regarded as modeled. Although these data are calculated using monitoring and modeling derived data the values represent essentially modeled loads. While this approach is very powerful it is imperative to clearly label these data as estimated (modeled). This is the main justification for using the stacked bar in the indicator plots.

2.Water year river input loads for 2009 have not been finalized. Loads for river input and flow were estimated by the USGS using a model fit to the entire data period of record. This method differed from that used to estimate all other water year river input monitoring loads that fit the statistical model to rolling 9-year data windows. No data for 2009 water-year below the fall-line non-point-source loads and point source loads were available due to data reporting lag, so contributions were estimated by using the 2008 load value. Therefore, results for water year 2009 are of limited quantitative value. CBP will update the 2009 load estimate as the finalized data become available (late spring). The 2009 bar chart needs to be labeled as provisional or estimated and subject to revision.  It should be noted that because provisional data is reported each year, results from previous reports will be updated and printed data and analysis is subject to change.

3.The flows that are super imposed on these load figures include provisional data (2005, 2006, 2007,2008, 2009) that are subject to revision.

References

Langland, M. J., S. W. Phillips, J. P. Raffensperger, and D. L. Moyer. 2005. Changes in streamflow and water quality in selected nontidal sites in the Chesapeake Bay basin, 1985-2003, p. 50. Scientific Investigations Report. USGS.

Linker, L. C., G. W. Shenk, R. L. Dennis, and J. S. Sweeney. 2000. Cross-media models of the Chesapeake Bay watershed and airshed. Water Quality and Ecosystem Modeling 1: 91-122.

Moyer, D. L. 2005. Quality Assurance Project Plan for the Virginia River Input Monitoring Program. USGS Water Resources.

Runkel, R. L., C. G. Crawford, and T. A. Cohn. 2004. Load Estimator (LOADEST): A FORTRAN Program for Estimating Constituent Loads in Streams and Rivers, p. 69. U.S. Geological Survey Techniques and Methods Book 4, Chapter A5. USGS.

Tenbus, F. J. 2006. Quality Assurance Project Plan for the Maryland River Input Monitoring Program, river input nutrient and sediment loading trends component, p. 41. USGS Water Resources.

U.S. Environmental Protection Agency. 2003. Setting and allocating the Chesapeake Bay basin nutrient and sediment loads. US EPA Chesapeake Bay Program Office.

River Flow Survey 

A.  Category/Name/Source/Contact

(1) Category of Indicator

_x_ Factors Impacting Bay and Watershed Health

___ Restoration and Protection Efforts

___ Watershed Health

___ Bay Health

(2) Name of Indicator: Total Freshwater Flow to the Bay 

(3) Data Set Description:  

For what purpose(s) were the data collected? (e.g., tracking, research, or long-term monitoring.) These data are used to track conditions in the bay and the rivers draining to the Chesapeake.

Which parameters were measured directly? Flow at the River Input stations was measured.

Which were obtained by calculation? Flow from several areas not monitored by the River Input. Seehttp://md.water.usgs.gov/monthly/bay.html

(4) Source(s) of Data:

Is the complete data set accessible, including metadata, data-dictionaries and embedded definitions? The data set is available and a description of the methods can be found at http://md.water.usgs.gov/publications/ofr-68-Bue10/.   If yes, please indicate where complete dataset can be obtained. Data set can be obtained from Katie Foreman at CBPO.

(5) Custodian of Source Data (and Indicator, if different): Joel Blomquist USGS

(6) CBPO Contact: Katie Foreman (CBP/University of Maryland Center for Environmental Science 800 YOUR-BAY)

B.  Communication Questions

(complete either part 1, 2, or 3)

1.  Restoration and Protection Efforts indicators only

(7a) How much has been completed since 1985 (or baseline year)?  How much has been completed since 2000?

(8a) How much was done last year?

(9a) What is the current status in relation to a goal?

(10a) What is the key story told by this indicator?

(11a) Why is it important to report this information?

(12a) What detail and/or diagnostic indicators are related to this reporting level indicator? (Detail and diagnostic indicators can be spatially-specific, parameter-specific, temporally-specific information, etc.)

2.  Bay Health or Watershed Health indicators only

(7b) What is the long-term trend?  (since start of data collection)

(8b) What is the short-term trend? (3 to 5 year trend)

(9b) What is the current status in relation to a goal?

(10b) What is the key story told by this indicator?

(11b) Why is it important to report this information?

(12b) What detail and/or diagnostic indicators are related to this reporting level indicator?

3.  Factors Impacting Bay and Watershed Health indicators only

(7c) What is the long-term trend?  (since start of data collection)

This indicator tracks annual variation in flows and as such has not been analyzed statistically for trends.

(8c) What is the short-term trend? (3 to 5 year trend)

The last 5 years have shown considerable variation in flow. Water year 2001 and 2002 were dry years whereas 2003 and 2004 were wet years.

(9c) What is the current status?

Flow was 30.8 billion gallons per day in 2009, which is below the long term (1938-present) average of 46.9 billion gallons per day.

 (10c) What does this indicator tell us?

Flow to the Bay has fluctuated considerably in recent years. These changes in flow influence pollutant loading and alter the salinity and stratification of the Bay. 

(11c) Why is it important to report this information?

Flow is a fundamentally important force shaping the conditions in the Bay and thus influence the water quality and habitat conditions for most species living in the Bay. 

(12c) What detail and/or diagnostic indicators are related to this reporting level indicator?

Detailed diagnostic indicators exist for this indicator although these indicators have not been linked to the flow indicator at this time.

C.  Temporal Considerations

(13) Data Collection Date(s): Water year 1938-2009

(14) Planned Update Frequency (e.g. - annual, bi-annual):

(a) Source Data: Monthly

(b) Indicator: Annual (water year)

(15) For annual reporting, month spatial data is available for reporting: Provisional water year data usually available by beginning of March.

D.  Spatial Considerations

(16) Type of Geography of Source Data (point, line polygon, other):

(17) Acceptable Level of Spatial Aggregation (e.g. - county, state, major basin, tributary basin, HUC):

(18) Are there geographic areas with missing data?  If so, where?

(19) The spatial extent of this indicator best described as:

(a) Chesapeake Bay (estuary)

(b) Chesapeake Bay Watershed

(c) Other (please describe): _______________________

Please submit any appropriate examples of how this information has been mapped or otherwise portrayed geographically in the past.

(20) Can appropriate diagnostic indicators be represented geographically?

E.  Data Analysis and Interpretation

(Please provide appropriate references and location of documentation if hard to find.) Bue, C.D., 1968, Monthly surface-water inflow to Chesapeake Bay: U.S. Geological Survey Open-File Report, Arlington, Va., November 1968, 45 p.

(21) Is the conceptual model used to transform these measurements into an indicator widely accepted as a scientifically sound representation of the phenomenon it indicates?  (i.e., how well do the data represent the phenomenon?)  YES

(22) What is the process by which the raw data is summarized for development and presentation of the indicator?   Historical daily values of streamflow are summarized into annual and monthly indicators.

(23) Are any tools required to generate the indicator data (e.g. - Interpolator, watershed model)

(24) Are the computations widely accepted as a scientifically sound? YES

(25) Have appropriate statistical methods been used to generalize or portray data beyond the time or spatial locations where measurements were made (e.g., statistical survey inference, no generalization is possible)?  

(26) Are there established reference points, thresholds or ranges of values for this indicator that unambiguously reflect the desired state of the environment? (health/stressors only) 

F.  Data Quality

(Please provide appropriate references and location of documentation if hard to find.)

(27) Were the data collected according to an EPA-approved Quality Assurance Plan?  

If no, complete questions 28a – 28d: According to USGS documented methods and quality assurance practices

(28a) Are the sampling design, monitoring plan and/or tracking system used to collect the data over time and space based on sound scientific principles? YES

(28b) What documentation clearly and completely describes the underlying sampling and analytical procedures used?  

(28c) Are the sampling and analytical procedures widely accepted as scientifically and technically valid? YES

(28d) To what extent are the procedures for quality assurance and quality control of the data documented and accessible? Web available

(29) Are the descriptions of the study or survey design clear, complete and sufficient to enable the study or survey to be reproduced? YES

(30) Were the sampling and analysis methods performed consistently throughout the data record? YES

(31) If datasets from two or more agencies are merged, are their sampling designs and methods comparable?

(32) Are uncertainty measurements or estimates available for the indicator and/or the underlying data set? NO

(33) (Do the uncertainty and variability impact the conclusions that can be inferred from the data and the utility of the indicator?

(34) Are there noteworthy limitations or gaps in the data record?  Please explain.

G.  Additional Information

(optional)

(35) Please provide any other information about this indicator you believe is necessary to aid communication and any prevent potential miss-representation.

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