CAST FAQs

General

CAST Users

Who is eligible to receive a login and use CAST?

Anyone who wants to use CAST may register for a login and use the tool. There are no restrictions on public access, and no charge for access.

What might happen if I share my CAST login account with another person?

If you were to share your login, and more than one person was using the account at the same time, then the person could overwrite your inputs. Please consider not sharing your login. Other users of CAST can use the system to share scenarios with you, and vice versa.

I forgot my login username and/or password for CAST. What can I do to get it or reset it?

Your login is your email. If you no longer have access to that email address, you will need to create a new account. If you forget your password, click on Forgot Password to reset it.

How can I update the information in my CAST user profile?

You can edit your CAST user profile once you create a login and are logged in. Click on Manage Profile, located at top right of the page. This allows you to change your user password, first name, last name, organization, group, and email address.

How may I receive updates about changes to CAST?

By setting up a login account on CAST you will receive occasional email updates through the email address you used as your login. If your email address changes, please update it on the Manage Profile page. If you no longer wish to receive updates, you must close your account. We will never solicit you to purchase any goods or services, nor share your login profile with anyone else. You also may check the software updates page and look for changes in the help pages on this site that indicate new features.

Scenario

How are future scenarios projected?

The data used to project future scenarios include the items below. The projection methods for these data are determined by the Chesapeake Bay Program Partnerships source sector workgroups.

  • Animal Populations
  • Animal per Animal Unit and manure produced per animal daily
  • Biosolids and agricultural spray irrigation
  • Nitrogen and phosphorus amount to meet crop need
  • Crop acres
  • Crop yield, e.g. bushels per acre
  • Inorganic fertilizer available in the watershed
  • Land Use
  • Nutrient concentration per animal manure type and county
  • Septic systems 
  • Soil phosphorus
  • CSO connections
  • Septic systems, RIB, and urban spray irrigation
  • Wastewater data
  • Atmospheric deposition

Add Scenario

I am getting an error in uploading my file. Why?

Mac users should save files for uploads as "Windows Formatted Text (.txt)", not Tab Delimited Text. When you hit return in Windows the computer puts a code of CRLF (carriage return + line feed) at the end of the line. Apparently, Macs put CR only so in Windows text just wraps together. So by saving as Windows Formatted Text it forces a CR+LF at the end.

Other users should save files as .txt. If errors persist, check the headers and make sure an extra character was not inadvertently added.

I am still getting an error in uploading my file. What can I check?

Verify that the file headers match those that are in the sample file. Next verify that the data or text meet the length requirement. For example, the state abbreviation can be no longer than two characters. If you typed "Maryland" rather than "MD", you will not be able to upload the file. If you typed XX, the file will upload, but that BMP will show up as an invalid BMP. If you are unable to resolve the problem use the Contact Us link for more help.

When uploading a file, can I use the individual load sources, not just groups?

Yes. Use this table to verify you are using the correct load sources or load source groups.

What is the difference among base scenario selections?

There are two base scenarios. Historic Trends is available for years before 2013 and Current Zoning is available for years after 2012. Current zoning is used for the Bay TMDL Milestones, Phase 3 WIPs and post-2012 progress.

Rates of change are dictated by the county-level population and employment projections (provided to CBPO by state agencies or state contractors). Pattern of change (e.g., infill development, proportion of growth in urban vs rural areas, and fine-scale probabilities of growth) are dictated by Census and satellite observations between 2000 and 2010. Constraints on change (e.g., zoning, employment and population densities, protected lands, already developed areas, steep slopes, wetlands, water) are dictated by regional, state, and local data sets generally representing 2011 – 2013 conditions. Shapes of change (e.g., shapes of simulated patches of new development) are dictated by a gravity surface to all roads (circa 2013) emphasizing the need for road access to all new developments. Shapes are circular when located far from roads are oblong near and adjacent to roads.

How can I see the BMPs of the shared scenarios?

You can create a new scenario copying the shared scenario’s BMPs or generate a report from the shared scenario under the Results option.

At what scale are the load calculations done?

All loads are calculated for the land-river segments using the unit load (pollutant lbs per acre) for each load source in each land-river segment. The unit load varies by land-river segment. Animal manure application to load source is calculated by county only.

What are land segments, river segments and land-river segments?

Land segments are counties or portions of counties where there is a distinct difference within the county, like a change in physiographic region. River segments are the areas that drain to a stream reach. These are not comparable to HUCs. Land-river segments are intersections of the two and are the smallest area in the model.

Do the data for wastewater use consistent methods across the jurisdictions?

In CAST-19, all wastewater loads are reported for the progress reporting year of July 1 to June 30. The BMPs in the progress scenarios all use the progress reporting year.

What are the annual scenarios?

The scenarios named like 2017Progress are the scenarios that include BMPs reported by the states to the Chesapeake Bay Program office from July 1 to June 30 of that year. The base conditions, including land use, animals and septics, are for that year. The version of base conditions is Historic Trends through 2013. Post 2013, Current Zoning Base conditions are used. The time-variable version of the Watershed Model used the annual scenarios for calibration. Updates to base conditions make the CAST annual scenarios different than those used in the Phase 6 calibration.

Invalid BMPs

Why did my scenario previously validate and now there are invalid BMPs?

There are two reasons that new BMPs are now invalid. First, you added, copied, or uploaded BMPs that were not previously in your scenario. Second, updates to CAST resulted in changes to how certain BMPs are validated. For example, earlier versions of CAST allowed grass and forest buffers to be applied to pasture. With the update, those BMPs now will not validate on the pasture load source. In addition submitting the exclusion fencing BMP in units of percent is no longer available. If the exclusion fencing BMP was in your scenario as a percent, it now will show up on the invalid BMP page.

Compare Scenario

Why aren’t all or any of my scenarios showing up on the dropdown?

There are two reasons that a scenario may not appear on the dropdown. You must first select both a geographic scale and a geographic area. Only scenarios that are for the same geographic area that you selected will be in the drop down menu. If you are looking for a scenario that is not in the dropdown, it is likely in a different geographic area. Second, the scenario may have been created, but not run. Scenarios must be run to generate results. If there are no results, then the scenario will not be on the dropdown.

How can I sort the tables on the pages?

Tables occur in multiple pages throughout. The default sorting is indicated by the highlighted column, with an arrow pointing up for ascending and down for descending. Sorting may be changed by clicking on that and any other sortable column. Clicking once reverses the order. Clicking twice removes sorting from the column. Clicking on another column will move sorting to that column.

How is percent change calculated?

The formula used to calculate load changes from scenario 1 to scenario 2 is: ((scenario 1-scenario 2)/scenario 1) * -1 * 100. In this way, load increases are positive and load decreases are negative.

How do I know what changed from my previous version?

Use Compare Scenarios which allows you to compare among multiple scenarios. If you want to see a change between scenarios, you must add a new scenario and copy BMPs from an existing scenario. Otherwise, the changes you make will overwrite what was there before and you will not be able to compare.

Why can't I see the load reductions from a single BMP?

BMPs are calculated in a particular sequence. The combination of various BMPs in a scenario affects the loads. Since the BMPs work as a treatment train, it is not possible to quantify the load reduction from any one particular BMP. A load per BMP would change from scenario to scenario, depending on the land use acres and other BMPs present. The Scenario Results page shows the load reductions from all of the BMPs combined together within their load source category. The typical load per BMP and the cost per load reduced ($/lb) have been calculated for reference and are provided at the county and state scales on the CAST Home Page under Costs.

There are efficiencies for most BMPs and that provides a gross way to compare among BMPs. However, when combining BMPs in a scenario, that exact efficiency may not be matched because of other BMPs in a scenario. That is why the pound reduced per acre and the cost per pound reduced are available. These data were created by running a scenario and sequentially removing each BMP, then replacing it before removing another BMP. This provides the load reduction per BMP in that scenario. More information is available on the CAST Home Page under Costs.

What are the loads attributed to “water”?

The land use water represents water bodies like streams. The loads attributed to water bodies are solely from atmospheric deposition.

Why are there phosphorus loads attributed to septic in some scenarios, but not others?

Septic source sector loads of course include septic systems, but also include urban spray irrigation and rapid infiltration basins (RIBs). Urban spray irrigation and RIBs have both nitrogen and phosphorus loads. Septic systems always include only nitrogen loads. Earlier years did not have urban spray irrigation and RIBs, so phosphorus may not show up in early annual scenarios.

What is the difference between the pre- and post-BMP acres?

The pre-BMP and post-BMP acres represent the change in acres from land use change BMPs, like buffers. These BMPs typically change the acres from a higher loading land use to a lower loading land use.

What is the spatial scale of the calculated loads?

All loads are calculated at the land-river segment scale.

What are land segments, river segments and land-river segments?

Land segments are counties or portions of counties where there is a distinct difference within the county, like a change in physiographic region. River segments are the areas that drain to a fourth order stream reach. These are not comparable to HUCs. Land-river segments are intersections of the two and are the smallest area modeled.

Why are the costs zero for some sectors?

It is likely that you have no BMPs for that sector. Costs are only summed for the scenario where there was both a BMP and a cost per BMP entered on the Cost Profiles sheet. If no cost was entered for a BMP, or a BMP sector, then no cost will be shown.

Reports

Why aren’t all or any of my scenarios showing up on the dropdown?

There are two reasons that a scenario may not appear on the dropdown. You must first select both a geographic scale and a geographic area. Only scenarios that are for the same geographic area that you selected will be in the drop down menu. If you are looking for a scenario that is not in the dropdown, it is likely in a different geographic area. Second, the scenario may have been created, but not run. Scenarios must be run to generate results. If there are no results, then the scenario will not be on the dropdown.

Why can't I see the load reductions from a single BMP?

BMPs are calculated in a particular sequence. The combination of various BMPs in a scenario affects the loads. Since the BMPs work as a treatment train, it is not possible to quantify the load reduction from any one particular BMP. A load per BMP would change from scenario to scenario, depending on the land use acres and other BMPs present. The Scenario Results page shows the load reductions from all of the BMPs combined together within their load source category. The typical load per BMP and the cost per load reduced ($/lb) have been calculated for reference and are provided at the county and state scales on the CAST Home Page under Costs.

There are efficiencies for most BMPs and that provides a gross way to compare among BMPs. However, when combining BMPs in a scenario, that exact efficiency may not be matched because of other BMPs in a scenario. That is why the pound reduced per acre and the cost per pound reduced are available. These data were created by running a scenario and sequentially removing each BMP, then replacing it before removing another BMP. This provides the load reduction per BMP in that scenario. More information is available on the CAST Home Page under Costs.

What are the loads attributed to “water”?

The land use water represents water bodies like streams. The loads attributed to water bodies are solely from atmospheric deposition.

What is the difference between the pre and post-BMP acres?

The pre-BMP and post-BMP acres represent the change in acres from land use change BMPs, like buffers. These BMPs typically change the acres from a higher loading land use to a lower loading land use.

What is the spatial scale of the calculated loads?

All loads are calculated at the land-river segment scale.

What are land segments, river segments and land-river segments?

Land segments are counties or portions of counties where there is a distinct difference within the county, like a change in physiographic region. River segments are the areas that drain to a fourth order stream reach. These are not comparable to HUCs. Land-river segments are intersections of the two and are the smallest area modeled.

Why are the costs zero for some BMPs or sectors?

It is likely that you have no cost associated with that BMP, or no BMPs in a sector. Costs are only summed for the scenario where there was both a BMP and a cost per BMP entered on the Cost Profiles sheet. If no cost was entered for a BMP, or no BMPs in a sector, then no cost will be shown.

Do the data for wastewater use consistent methods across the jurisdictions?

Wastewater loads are reported for the progress reporting year of July 1 to June 30. The BMPs in the progress scenarios all use the progress reporting year.

Where can I find the Chesapeake Bay Program's Phase 5 tools and reports?

The Chesapeake Bay Program's Phase 5 tools (BayTAS and the TMDL Tracker) have been retired. Beginning with 2018 Progress, the CBP partnership has fully transitioned to the Phase 6 model. Phase 5.3.2 versions of Final Summary Loads and Summary BMPs reports (progress years 1985-2017) are available for download here.

Understanding Results

Why am I not receiving credit for all the BMP implementation in a HUC?

If the geography submitted for a report is HUC, then the data will show the amount credited for the area in the HUC. Calculations are performed for land-river segments and then the portion that falls within a HUC is attributed to that HUC. The difference in the acres credited between your input and the BMP report is simply due to scale. You are submitting for a HUC, and calculations in CAST are done on land-river segments (lrsegs). Consider a HUC that is equal to portions of two lrsegs as 50% of one lrseg and 100% of other lrseg and each segment had an equal area for that load source.

Lrseg 1 = 100 acres with 50% in HUC
Lrseg 2 = 100 acres with 100% in HUC
HUC acres = 150 acres

100 acres of BMP submitted in HUC
33 acres go to lrseg 1
66 acres go to lrseg 2 which is 100 % credited in the 2 lrsegs

Report geographic scale is by the HUC which has
33 acres in lrseg 1 (all of lrseg 1 not just the HUC portion because that is how BMPs are processed on the lrseg scale)
66 acres in lrseg 2

So credited for the HUC = 33 * 0.5 because only half of lrseg 1 is in the HUC + 66 = 16.6666 + 66 = 82.6666

When I look at the BMP Submitted vs. Credited report, I see that there are some BMPs that were not credited. Why not?

If you applied more implementation on a land use than there were acres available, then the excess is not credited. Even if the pre-BMP land use acres table indicates the land is there, it may not be by the time you added in buffers and other land use change BMPs. This table and the excess column are a good check to make sure you are getting the reductions you intended.

Why do I get different results for some shared or public scenarios?

The E3 scenario shared by CBP Admin was run with special conditions not available to CAST users. Creating a new scenario by copying the BMPs from those scenarios will produce different load results. The special conditions are the control of effects from land use differences.

Why are certain agricultural load sources increasing when I only put BMPs on other agricultural load sources?

If you put a nutrient reduction BMP, like Nutrient Management, on crop and hay, the pasture load will increase. The manure and fertilizer is applied to each crop type according to a curve. So restricting the amount on one crop moves the manure and fertilizer to another crop or to pasture. Details about the curves and how the load sources influence each other may be found in the CAST Model Documentation page, Section 3, found under the About header in the top navigation bar.

Why did my sediment load change when the BMP I added only impacts nitrogen?

The riparian pasture deposition sediment load is calculated as a ratio based on the nitrogen load. The sediment is 122.42 pounds per pound of total nitrogen. This ratio came from the watershed-wide sediment load from Phase 5.3.2 Watershed Model for the land use trampled riparian pasture. When a BMP changes nitrogen, then the sediment also changes.

Why did my nitrogen loads increase with Manure Treatment Technology or Manure Transport?

Removing manure without also controlling the amount of replacement inorganic fertilizer results in the same rate of inorganic fertilizer being applied as when manure was applied. While phosphorus will be reduced, nitrogen loads may increase. When using these manure BMPs, increase the amount of the Nutrient Management Rate BMP to control the amount of replacement inorganic fertilizer. Additionally, the runoff of inorganic fertilizer is higher than manure, which also contributes to the potential increase in nitrogen loads. These runoff rates are based on multiple peer-reviewed research articles. More documentation may be found in the CAST Model Documentation page found under the About header in the top navigation bar.

Why are changes in load on all agricultural load sources when I input BMPs that should only impact manured agricultural load sources?

One of the parameters used to calculate the phosphorus loads is the amount of phosphorus in the soil. That is calculated across all crop load sources together, following the decision of the Chesapeake Bay Program Partnership. When manure is changed, such as with the manure transport BMP, the impact will be on all crop load sources, not just those that have manure applications. The non-manured load sources that show this change are soybeans, grains without manure, and silage without manure.

Why is the stream bed and bank load changing in scenarios where I didn't change the BMPs on the stream load source?

The stream loads will vary in every scenario because other BMPs impacted the loads that are delivered to the stream load source. The stream load is calculated as a ratio to the total edge-of-stream (EOS) load from the non-stream load sources to the stream load source. Sediment also is adjusted as 4/3rds of the impervious load.

Why are there phosphorus loads attributed to septic in some scenarios, but not others?

Septic source sector loads of course include septic systems, but also include urban spray irrigation and rapid infiltration basins (RIBs). Urban spray irrigation and RIBs have both nitrogen and phosphorus loads. Septic systems always include only nitrogen loads. Earlier years did not have urban spray irrigation and RIBs, so phosphorus may not show up in early annual scenarios.

Why are the WIP wastewater loads higher than current years?

There are more people moving into the Chesapeake Bay Watershed and those people produce new demands on wastewater systems. There are even new plants scheduled to come on line. This will result in the overall wastewater load increasing. However, the efficacy of nutrient and sediment reductions from wastewater loads has increased substantially over time. The total load may increase even while the load per gallon decreases. To confound this, the WIP inputs were updated to account for new or different facilities. These same inputs may not have been updated for the annual scenarios.

How are BMPs and nutrients applied in scenarios for scenarios that are not official annual progress?

Scenario years after 2017 use projected data. The 2017 base conditions are the last year that all data are available to calculate animal manure and crop acres. Years after 2017 are projected. In scenarios you create for any year, only the land use change BMP implementation in excess of that in the base conditions for that year are credited. The land use change is already accounted for in the base condition land, and this ensures that change is not credited twice. Where there are no annual BMPs reported, such as with a future year like 2023, then 2017 is used to assess if land use change BMPs are greater than those reported.

The nitrogen and phosphorus nutrients are applied to agricultural load sources using the fraction of crop need met in that year's progress. The 2017 plant-available phosphorus available for application to the agricultural load sources is also used for years after 2017. For years up to and including 2017, the crop need and plant-available phosphorus is calculated based on nutrients available, location of nutrients after BMPs, and crop need and uptake for that year. If the amount of crop need met in 2017 was 110%, then 110% of crop need will be met in 2018. The application rate will be even higher if Manure Transport and/or the Nutrient Management BMP was implemented in 2017 but not in later years.

When selecting base conditions for years between 1984 and 2017, the amount of crop need calculated from the ratio of all nutrient inputs applied to meet crop need are defined by the official annual progress scenario for that year.

For phosphorus, the difference between the amount of manure transport in 2017 and later years is subtracted from the amount of manure nutrients applied after other nutrients are applied to meet the proportion of crop need met in 2017. The implication is that if more manure is transported out of a location than was transported out in the 2017 Progress, the phosphorus applied is effectively lowered. Conversely, if less manure is transported out of a location than was transported out in the 2017 Progress, the phosphorus applied increases.

What data are used in future scenarios?

The data used to project future scenarios include the items below. The projection methods for these data are determined by the Chesapeake Bay Program Partnerships source sector workgroups.

  • Animal Populations
  • Animal per Animal Unit and manure produced per animal daily
  • Biosolids and agricultural spray irrigation
  • Nitrogen and phosphorus amount to meet crop need
  • Crop acres
  • Crop yield, e.g. bushels per acre
  • Inorganic fertilizer available in the watershed
  • Land Use
  • Nutrient concentration per animal manure type and county
  • Septic systems 
  • Soil phosphorus
  • CSO connections
  • Septic systems, RIB, and urban spray irrigation
  • Wastewater data
  • Atmospheric deposition

Why are my EOT loads higher than EOS loads? Where did that sediment come from?

Delivery factors indicate how much of a load is delivered to the next scale. For example, an EOT delivery factor of one indicates that there were no river processes that changed the amount delivered. An EOT delivery factor of less than one indicates that the river was a sink for the load. A delivery factor greater than one indicates the river is a source for the load. Land-river segments outside of the Chesapeake Bay Watershed are zero. There are three land-river segments in the Chesapeake Bay Watershed (CBWS) with EOT delivery factors of zero: N51095JBO_7051_0001, N24005WM0_3881_3880, N24013WM0_3881_3880. The two in MD are Liberty Reservoir, which is used for water supply. The one in Virginia is the location of the Little Creek Reservoir.

Why are some of the loads negative?

The stream restoration BMP has no domain for the feet or loads. As such, the edge-of-stream (EOS) and edge-of-tide (EOT) loads can go negative for that load source.

Edge-of-tide (EOT) loads for shoreline and feeding space load sources can be lower than edge-of-stream (EOS) loads, or even negative. BMPs can drive nitrogen, phosphorus and sediment loads less than zero. The BMPs that may drive EOT TN loads less than zero include Manure Treatment Technologies and any of the ammonia reduction BMPs, all of which are applied at the EOT scale. These BMPs are reducing the volatilized ammonia. Without the ammonia reduction BMPs in place, the ammonia moves into the atmosphere and is reflected in the atmospheric deposition load. With the BMP, the land load is adjusted to show that the ammonia stays on the land. For example, a feeding operation may have perfect controls for runoff, but no volatilization controls. With the addition of a lagoon cover, the ammonia will no longer volatilize and be deposited elsewhere. Instead, the ammonia stays on the feeding operation. The oyster restoration BMP also is credited at EOT, and can make the EOT shoreline load negative. These BMPs are applied at the EOT scale.

This situation can occur in segments outside of the Chesapeake Bay Watershed where the EOT load without BMPs is zero, since delivery is to the ocean or another watershed. Those zero EOT loads can become negative with the addition of the Manure Treatment Technology and the ammonia reduction BMPs. A comparable situation is where there is a smokestack outside the CBWS emitting nitrogen that is deposited within the CBWS. Controls on that smokestack increase the load at the location of the smokestack. An animal operation outside the CBWS works the same way. The load that was volatilizing before the BMP was depositing ammonia some distance away in the CBWS. With the BMP, the load stays on the feeding space land and is shown as a negative load, offsetting the atmospheric load formerly deposited in the CBWS.

What features are different in Phase 6 compared with Phase 5.3.2?

Some changes include:

  1. Transition from having spatially defined federal land uses to agencies. Agency types include approximately a dozen different federal entities as well as some Maryland-specific stormwater designations.
  2. Land uses are now denoted as load sources. Load sources are a more appropriate designation since there are loads that do not have land areas associated with them. Examples are shoreline and stream bed and bank.
  3. BMPs must be input for an agency, load source and a geographic location. Geographic locations can be general like a state, or specific like a hydrologic unit code (HUC).
  4. Phase 5.3.2 had edge-of-stream (EOS) loads for big streams (approximately a 3rd order stream or larger) and the delivered (DEL) load to the Chesapeake Bay. Phase 6 has edge-of-small stream loads (EOS) and the delivered load to the tidal portion of the Chesapeake Bay (EOT).
  5. Non-point sources of nitrogen and phosphorus include: biosolids, animal manure, inorganic fertilizer, atmospheric deposition, septic systems, and rapid infiltration basins.
  6. Animals and their manure remain based on county-level estimates from the National Agricultural Statistics Service. The loads are apportioned within a county using the land use so that results can be at multiple scales. As with the previous model version, the specificity of manure loads is most accurate at the county-scale or larger.
  7. There have been a number of changes to manure calculations. All manure is shown as dry tons. Nutrient concentrations in animal manure increased based on the latest data. The feeding space load increased because the time in pasture generally decreased. The acres for feeding space areas decreased. The area is now defined using the acres per animal by animal type. Previously the acres were defined using the number of farms and acres per farm.
  8. Directly excreted manure is apportioned to Riparian Pasture Area (RPA) and Pasture. There is no more trampled riparian pasture (TRP). RPA has zero acres. Instead manure is distributed based on the amount of time animals spend stream-side. The stocking rate for pasture varies by state. Exclusion fencing moves the load out of RPA and is now reported as acres and animal units. If only acres are submitted, there is an assumed number of animal units.
  9. Fertilizer is now on a mass balance approach. In the previous version, it was distributed based on crop need. Now crop need informs where it is applied, but the total amount is constrained based on fertilizer sales data. CAST users will see a potential decrease in the benefit of the manure transport BMP as a result.
  10. The poultry phytase BMP is eliminated. That benefit is now assumed in the manure nutrient concentrations.

Which inputs are applied to each of the Phase 6 load sources?

The inputs do not apply to all of the Phase 6 load sources. For example, manure nitrogen and phosphorus are not attributed to developed lands. Only leguminous plants fix nitrogen, so the fixed nitrogen input only applies to load sources that contain crops or plants that are leguminous. Atmospheric deposition of nitrogen and phosphorus falls on all load sources with acres. This table of Loads by Load Source provides a ready reference of the inputs for each load source.

Inputs by Load Source

Cost Profiles

Are developed sector costs for new/redevelopment or retrofits?

Developed BMP costs average the costs of new/redevelopment and retrofits. 

Where is more detailed information on costs?

The detailed source data for costs are available on the CAST home page under Costs.

How can I see the shared cost profiles?

To see those configurations, select "Copy" located next to the name of the cost profile in the Cost Profiles Shared with Me table. You then may edit the costs in your copy of the profile. Additional help is available for using those options once you are on the Edit Costs page.

Why are my costs so high?

The costs in this tool are all those in a plan. They are not costs that are only incremental to the TMDL. The costs in this tool are all of the costs in a scenario and include BMPs already implemented as well as current commitments under existing regulatory requirements. It is possible that costs could be reduced substantially by selecting BMPs that require a lower investment. For example, instead of selecting filtering practices to control urban stormwater, bioswales could be used. Bioswales are more effective and less expensive than filtering practices.

Why didn’t my costs change when I added a BMP?

Check the cost page to make sure that there are amounts entered for that BMP. There are some BMPs that do not have costs, depending on the cost profile you copied from and the edits you made to your cost profiles.

Land Policy BMPs

Why are the land policy BMPs not showing up as an option?

Land Policy BMPs are available only when BMP type is "planning" and Base Year is "2025". Some Land Policy BMPs are eligible for only historic trends or current zoning base conditions.

What is the anticipated effect of each of the land policy BMPs by state and county?

This spreadsheet shows a comparison of absolute load and percent difference in load for nitrogen and phosphorus by state and county for the Chesapeake Bay-wide BMPs. Note that this was developed in CAST-17d and the current CAST version is CAST-19. The loads will be slightly different but the direction will be the same.

Developed BMPs

Why am I getting an error whenever I try to add this BMP?

If you get an error message that a BMP cannot be added, it is likely already added in units of percent. You may edit the amount of implementation in that table, or edit the BMP to change the amount or percent to avoid the conflict. BMPs entered as percents cannot be entered on the same or overlapping geographies and load sources, but BMPs entered as acres can overlap geographies and load sources. An example of an overlapping geography is a county and a state. An example of overlapping load sources are developed and impervious because developed includes impervious.

How can I sort the tables on the BMP pages?

Tables occur in multiple pages throughout. The default sorting is indicated by the highlighted column, with an arrow pointing up for ascending and down for descending. Sorting may be changed by clicking on that and any other column. Clicking once reverses the order. Clicking twice removes sorting from the column. Clicking on another column will move sorting to that column.

How do I filter tables on the BMP pages?

Records may be selected by using the filter option. There are multiple options for how to filter, and these options work the same as excel or most other applications with filtering capacity.

The BMP names we use don't match those used by the Chesapeake Bay Program. How do I know which BMP to select?

A cross-walk of commonly used BMP names to Chesapeake Bay Program BMP names is available on the Home page under Source Data. This cross walk includes NRCS practice names. Note that only one BMP should be entered where there are multiple BMPs treating the same area, such as occurs with a treatment train. Select the BMP that is dominant.

Why do I have to enter geographic scale on this BMP page when I defined it for the scenario? What if I pick state for a BMP, but defined the entire scenario as county?

The geographic scale may be different than the scale at which the scenario was created. Where a geographic area for a BMP is selected as larger than that of the scenario, then the load estimates will show only the loads for the area of the scenario, even though the BMP was applied to a larger area. That is, the user will not see the load reduction for the area outside of the scenario-defined boundary. The reduction will be parsed to the entire area specified by the BMP, even if your scenario was defined as something smaller.

Are the acres in the pre-BMP load source the entire county or just the Chesapeake Bay watershed? Why do the total acres in my county seem incorrect?

Some counties have only a portion of the county in the Chesapeake Bay Watershed. The user selects the geography for the scenario and each BMP. This geography may include the entire county or just the portion that drains to the Chesapeake Bay Watershed, denoted as CBWS-only. Acres shown in the pre-BMP load source table are those in the geography selected when the scenario was created. The pre-BMP animal table shows the number of animals in the entire county--data are not available at a finer scale. The assumption made in the model is that animals are equally distributed in the county.

Why can't I edit the BMP cost?

Cost components may be edited in the Cost Profile. The BMP pages and results pages will update with the new cost once you reselect it under scenario details.

Why doesn't the cost change when I change the total amount implemented?

The cost shown is the annualized cost per unit. That means that the cost is for one year of implementation (annualized) and is for a single unit of implementation, commonly acres or acres treated.

What if I have more than one BMP treating the same area, such as with a treatment train?

Where BMPs are used in a treatment train (multiple BMPs treating the same area of land), then select the one BMP that is dominant. The BMP effectiveness values account for the typical treatment train effects.

What is CSS?

CSS in the load source name is the abbreviation for combined sewer systems. The CSS areas are not credited with reductions from nonpoint source BMPs that are entered on this page. Those areas are credited with reductions from point sources, which have the measured outflow.

What is the difference between MS4, regulated and nonregulated load sources and why would I put a BMP on one versus the other?

Municipal Separate Stormwater and Sewer (MS4) load sources are those developed areas that fall within the MS4 areas. The MS4 load sources exclude agricultural load sources. The MS4 GIS layers are available on the CAST Home page under Map Tools and Spatial Data. Regulated is used only for the construction load source. There are CSS and regulated construction, but no non-regulated construction. The MS4, regulated, and nonregulated load sources are all modeled with the same load. Those load sources are separated solely for the convenience of planners.

Why doesn’t the Pre-BMP Load Source table change when I input load source change BMPs?

The Pre-BMP Load Source table is the amount before any BMPs are implemented. That means that those BMPs that change the load source, like forest and grass buffers, are not credited yet in the Pre-BMP Load Source table. Because the BMPs are calculated in a specific sequence, but you can add them in any sequence, this table is static. Go to the Results page to see the post-BMP load source.

Why does the list of load sources change depending on the BMP? Why does the list of BMPs change when I have a load source selected?

Users may find it more convenient to add BMPs beginning with the load source or with the BMP. Users may begin with either selection, and the other restricts the dropdown to only the eligible options.

How can I tell the difference between groups of load sources and the individual load sources?

Load sources and load source groups are listed in the dropdown. A cross-walk of load sources to load source groups is available in the Source Data, which may be accessed from the CAST Home page. The tab "Load source group components" lists the Chesapeake Bay Program modeled load sources along with the groups of those load sources. It is usually more convenient to apply BMPs to load source groups that encompasses multiple load sources, since that is the scale at which planning generally occurs.

How are total and impervious acres used in the Stormwater Performance Standard BMPs?

The impervious acres are used to calculate inches treated which is used to determine the efficiency. Total acres are the acres treated with that efficiency. Impervious acres are not used for the total impervious acres treated. Meaning if you submit 100 acres and 50 impervious it does not mean that 50 impervious acres are treated. The makeup of the 100 acres is done like any other BMP - proportionally.

What is the equation for calculating the Stormwater Performance Standard - Runoff Reduction (RR) removal amount?

Inches treated = RunoffStorageVolume*12 ) / ImperviousAcres   If this is below .05 then it is set to .05, if above 2.5 then its set to 2.5.

Nitrogen = 0.0308*InchesTreated^5 - 0.2562*InchesTreated^4 + 0.8634*InchesTreated^3 - 1.5285*InchesTreated^2 + 1.5010*InchesTreated - 0.0130

Phosphorus = 0.0304*InchesTreated^5 - 0.2619*InchesTreated^4 + 0.9161*InchesTreated^3 - 1.6837*InchesTreated^2 + 1.7072*InchesTreated - 0.0091

Sediment = 0.0326*InchesTreated^5 - 0.2806*InchesTreated^4 + 0.9816*InchesTreated^3 - 1.8039*InchesTreated^2 + 1.8292*InchesTreated - 0.0098

What is the equation for calculating the Stormwater Performance Standard - Stormwater Treatment (ST) removal amount?

Inches treated = RunoffStorageVolume*12 ) / ImperviousAcres If this is below.05 then it is set to.05, if above 2.5 then its set to 2.5.

Nitrogen = 0.0152*InchesTreated^5 - 0.1310*InchesTreated^4 + 0.4581*InchesTreated^3 - 0.8418*InchesTreated^2 + 0.8536*InchesTreated - 0.0046

Phosphorus = 0.0239*InchesTreated^5 - 0.2058*InchesTreated^4 + 0.7198*InchesTreated^3 - 1.3229*InchesTreated^2 + 1.3414*InchesTreated - 0.0072

Sediment = 0.0304*InchesTreated^5 - 0.2619*InchesTreated^4 + 0.9161*InchesTreated^3 - 1.6837*InchesTreated^2 + 1.7072*InchesTreated - 0.0091

Stormwater performance standards ask for input in acre-feet. I only know inches treated. What should I input?

The Expert Panel that developed this BMP issued guidance that required input as acre-feet. The basic formula for this conversion is:

acre-feet = (Impervious Area* inches treated) / 12

Download the Expert Panel report from the CAST Home page under BMPs. Each state has different engineering parameters for determining the inches treated. If the engineering parameter is in acre-feet, you can use the above formula. Otherwise, use the engineering parameter in the equation. The engineering parameters are summarized below.

Specific Engineering Parameter (EP) Defining Runoff Volume CapturedSource
DCDivide SWRv (stormwater retention volume, cubic feet) by 43,560 and insert into Equation XCell C-30 in 2012 DDOE Compliance Spreadsheet
DERunoff Reduction Depth (inches)Directly from DE DURMM v. 2 Model Output
FEDD (95% rainfall depth, inches) less initial abstraction for predevelopment conditionEPA, 2009 and DOD, 2010
MDDivide ESD Runoff Volume (cubic feet) by 43,560 and insert into Equation XCell C-66 in MD ESD TO MEP Spreadsheet (2012)
NYInsert WQv (water quality volume, acre-feet) into Equation XSee 2010 Design Manual
PADivide 2-year Volume Increase of Runoff Volume between the proposed conditions and the existing conditions (cubic feet) by 43,560 and insert into Equation XCell C-51 in Tab WS4 of 2012 CSN PA Stormwater Spreadsheet
VAPost Development treatment volume (acre-feet) inserted into Equation XCell B-49 on Site Data page (tab 1) in 2012 VA DCR Compliance Spreadsheet
WVTarget Tv (treatment volume, acre- feet) inserted into Equation XCell A-80 in 2011 WVDEP Compliance Spreadsheet

Equation X is a site specific conversion factor equation: (12 * EP) / IA Where: EP = State-Specific Engineering Parameter (in acre-feet) and IA = Impervious Area (acres)

My stormwater project uses a mix of practices. Which should I use?

Where a mix of stormwater treatment and runoff reduction practices are used within the same development project, the designer should use the curve based on either the largest single practice used in the project or the one(s) that provide the majority of the runoff capture volume.

Why are there so many protocols for Stream Restoration and Shoreline Management? What do they all mean?

The protocols were defined by the Expert Panel and are extensively documented in the reports. The reports are available for download from the CAST Home page under BMPs.

Septic BMPs

Why am I getting an error whenever I try to add this BMP?

If you get an error message that a BMP cannot be added, it is likely already added in units of percent. You may edit the amount of implementation in that table, or edit the BMP to change the amount or percent to avoid the conflict. BMPs entered as percents cannot be entered on the same or overlapping geographies and load sources, but BMPs entered as acres can overlap geographies and load sources. An example of an overlapping geography is a county and a state.

How can I sort the tables on the BMP pages?

Tables occur in multiple pages throughout. The default sorting is indicated by the highlighted column, with an arrow pointing up for ascending and down for descending. Sorting may be changed by clicking on that and any other column. Clicking once reverses the order. Clicking twice removes sorting from the column. Clicking on another column will move sorting to that column.

How do I filter tables on the BMP pages?

Records may be selected by using the filter option. There are multiple options for how to filter, and these options work the same as excel or most other applications with filtering capacity.

The BMP names we use don't match those used by the Chesapeake Bay Program. How do I know which BMP to select?

A cross-walk of commonly used BMP names to Chesapeake Bay Program BMP names is available on the Home page under BMPs. This cross walk includes NRCS practice names. Note that only one BMP should be entered where there are multiple BMPs treating the same area, such as occurs with a treatment train. Select the BMP that is dominant.

Why can't I edit the BMP cost?

Cost components may be edited on the costs page. The BMP pages and results pages will update with the new cost once you reselect it under scenario details.

Why doesn't the cost change when I change the total amount implemented?

The cost shown is the annualized cost per unit. That means that the cost is for one year of implementation (annualized) and is for a single unit of implementation, commonly acres or acres treated.

Does the load for wastewater treatment plants increase when I connect septics?

The septic connection BMP eliminates the septic load for the number of systems selected. The load is assumed to be captured in the wastewater data. Wastewater loads are measured, and the measured load is reported. This measured load will include the loads from the newly-connected septic areas.

Natural BMPs

Why am I getting an error whenever I try to add this BMP?

If you get an error message that a BMP cannot be added, it is likely already added in units of percent. You may edit the amount of implementation in that table, or edit the BMP to change the amount or percent to avoid the conflict. BMPs entered as percents cannot be entered on the same or overlapping geographies and load sources, but BMPs entered as acres can overlap geographies and load sources. An example of an overlapping geography is a county and a state. An example of overlapping load sources are natural and wetlands because natural includes wetlands.

How can I sort the tables on the BMP pages?

Tables occur in multiple pages throughout. The default sorting is indicated by the highlighted column, with an arrow pointing up for ascending and down for descending. Sorting may be changed by clicking on that and any other column. Clicking once reverses the order. Clicking twice removes sorting from the column. Clicking on another column will move sorting to that column.

How do I filter tables on the BMP pages?

Records may be selected by using the filter option. There are multiple options for how to filter, and these options work the same as excel or most other applications with filtering capacity.

The BMP names we use don't match those used by the Chesapeake Bay Program. How do I know which BMP to select?

A cross-walk of commonly used BMP names to Chesapeake Bay Program BMP names is available on the Home page under BMPs. This cross walk includes NRCS practice names. Note that only one BMP should be entered where there are multiple BMPs treating the same area, such as occurs with a treatment train. Select the BMP that is dominant.

Why do I have to enter geographic scale on this BMP page when I defined it for the scenario? What if I pick state for a BMP, but defined the entire scenario as county?

The geographic scale may be different than the scale at which the scenario was created. Where a geographic area for a BMP is selected as larger than that of the scenario, then the load estimates will show only the loads for the area of the scenario, even though the BMP was applied to a larger area. That is, the user will not see the load reduction for the area outside of the scenario-defined boundary. The reduction will be parsed to the entire area specified by the BMP, even if your scenario was defined as something smaller.

Are the acres in the pre-BMP load source the entire county or just the Chesapeake Bay watershed? Why do the total acres in my county seem incorrect?

Some counties have only a portion of the county in the Chesapeake Bay Watershed. The user selects the geography for the scenario and each BMP. This geography may include the entire county or just the portion that drains to the Chesapeake Bay Watershed, denoted as CBWS-only. Acres shown in the pre-BMP load source table are those in the geography selected when the scenario was created.

Why can't I edit the BMP cost?

Cost components may be edited on the costs page. The BMP pages and results pages will update with the new cost once you reselect it under scenario details.

Why doesn't the cost change when I change the total amount implemented?

The cost shown is the annualized cost per unit. That means that the cost is for one year of implementation (annualized) and is for a single unit of implementation, commonly acres or acres treated.

How should I enter BMPs on the shoreline load source?

Shoreline BMPs are assumed to be in the scenario for years earlier than 2008. Only enter shoreline BMPs implemented in 2008 or later.

How does stream restoration work?

Streambank restoration reduces the load from the stream bed and bank and also changes the amount of deposition. Floodplain deposition is characterized as a stream delivery ratio that affects both the edge-of-stream and streambank loads. This ratio also changes the delivered load reduction from the streambank restoration BMP. When entering the BMP, any amount may be reduced. That is, the BMP can reduce more load than exists driving the load for this load source negative.

Agriculture BMPs

Why am I getting an error whenever I try to add this BMP?

If you get an error message that a BMP cannot be added, it is likely already added in units of percent. You may edit the amount of implementation in that table, or edit the BMP to change the amount or percent to avoid the conflict. BMPs entered as percents cannot be entered on the same or overlapping geographies and load sources, but BMPs entered as acres can overlap geographies and load sources. An example of an overlapping geography is a county and a state. An example of overlapping load sources are natural and wetlands because natural includes wetlands.

How can I sort the tables on the BMP pages?

Tables occur in multiple pages throughout. The default sorting is indicated by the highlighted column, with an arrow pointing up for ascending and down for descending. Sorting may be changed by clicking on that and any other column. Clicking once reverses the order. Clicking twice removes sorting from the column. Clicking on another column will move sorting to that column.

How do I filter tables on the BMP pages?

Records may be selected by using the filter option. There are multiple options for how to filter, and these options work the same as excel or most other applications with filtering capacity.

The BMP names we use don't match those used by the Chesapeake Bay Program. How do I know which BMP to select?

A cross-walk of commonly used BMP names to Chesapeake Bay Program BMP names is available on the Home page under BMPs. This cross walk includes NRCS practice names. Note that only one BMP should be entered where there are multiple BMPs treating the same area, such as occurs with a treatment train. Select the BMP that is dominant.

Why do I have to enter geographic scale on this BMP page when I defined it for the scenario? What if I pick state for a BMP, but defined the entire scenario as county?

The geographic scale may be different than the scale at which the scenario was created. Where a geographic area for a BMP is selected as larger than that of the scenario, then the load estimates will show only the loads for the area of the scenario, even though the BMP was applied to a larger area. That is, the user will not see the load reduction for the area outside of the scenario-defined boundary. The reduction will be parsed to the entire area specified by the BMP, even if your scenario was defined as something smaller.

Are the acres in the pre-BMP load source the entire county or just the Chesapeake Bay watershed? Why do the total acres in my county seem incorrect?

Some counties have only a portion of the county in the Chesapeake Bay Watershed. The user selects the geography for the scenario and each BMP. This geography may include the entire county or just the portion that drains to the Chesapeake Bay Watershed, denoted as CBWS-only. Acres shown in the pre-BMP load source table are those in the geography selected when the scenario was created.

Why can't I edit the BMP cost?

Cost components may be edited on the costs page. The BMP pages and results pages will update with the new cost once you reselect it under scenario details.

Why doesn't the cost change when I change the total amount implemented?

The cost shown is the annualized cost per unit. That means that the cost is for one year of implementation (annualized) and is for a single unit of implementation, commonly acres or acres treated.

Why can't I add enhanced Nutrient Management, decision agriculture or Tier 1, 2, and 3 Nutrient Management BMPs? What happened to poultry litter injection?

The nutrient management suite of BMPs was revised from nutrient management efficiency, enhanced nutrient management, and decision agriculture to the Tier BMPs and then to the current version that is available from the dropdown. The new suite of nutrient management BMPs includes core, placement, rate and timing. These nutrient management BMPs are not equivalent to the previous versions of nutrient management BMPs. Poultry litter injection and liquid injection are considered a component of the new Nutrient Management BMPs, and are no longer available.

How are all of the input amounts for exclusion fencing used?

Once the buffer with exclusion fencing is selected, three measurement boxes become available. The primary measure includes a drop down list to choose area in acres or length in feet. One of the two is required. If you report area in acres, those are converted to width and length. If you report length in feet, then those are used directly. Type in width in units of feet. This is not required. If no width is reported, the default of 10 feet for narrow buffers and 35 feet for standard buffers is used to determine length. Type in animal units fenced. This is not required. If you report animal units, then the manure from those animals is removed from direct application to the stream. If left blank, the default is 17.6 animal units per 1,000 feet. Where acres and width are entered, the width is used to calculate a length using a default width (10 feet for narrow buffers and 35 feet for standard buffers). Where a width is entered that is less than 35 feet for a standard buffer, a message alerts you to use a narrow buffer BMP. Where a width greater than 10 feet is entered for a narrow buffer, a message alerts you to use the standard buffer BMP.

Animal BMPs

Why am I getting an error whenever I try to add this BMP?

If you get an error message that a BMP cannot be added, it is likely already added in units of percent. You may edit the amount of implementation in that table, or edit the BMP to change the amount or percent to avoid the conflict. BMPs entered as percents cannot be entered on the same or overlapping geographies and animal types, but BMPs entered as number of animals can overlap geographies and load sources. An example of an overlapping geography is a county and a state. An example of overlapping animal types are poultry and broilers because poultry includes broilers.

How can I sort the tables on the BMP pages?

Tables occur in multiple pages throughout. The default sorting is indicated by the highlighted column, with an arrow pointing up for ascending and down for descending. Sorting may be changed by clicking on that and any other column. Clicking once reverses the order. Clicking twice removes sorting from the column. Clicking on another column will move sorting to that column.

How do I filter tables on the BMP pages?

Records may be selected by using the filter option. There are multiple options for how to filter, and these options work the same as excel or most other applications with filtering capacity.

The BMP names we use don't match those used by the Chesapeake Bay Program. How do I know which BMP to select?

A cross-walk of commonly used BMP names to Chesapeake Bay Program BMP names is available on the Home page under BMPs. This cross walk includes NRCS practice names. Note that only one BMP should be entered where there are multiple BMPs treating the same area, such as occurs with a treatment train. Select the BMP that is dominant.

Why do I have to enter geographic scale on this BMP page when I defined it for the scenario? What if I pick state for a BMP, but defined the entire scenario as county?

The geographic scale may be different than the scale at which the scenario was created. Where a geographic area for a BMP is selected as larger than that of the scenario, then the load estimates will show only the loads for the area of the scenario, even though the BMP was applied to a larger area. That is, the user will not see the load reduction for the area outside of the scenario-defined boundary. The reduction will be parsed to the entire area specified by the BMP, even if your scenario was defined as something smaller.

Are the acres in the pre-BMP load source the entire county or just the Chesapeake Bay watershed? Why do the total acres in my county seem incorrect?

Some counties have only a portion of the county in the Chesapeake Bay Watershed. The user selects the geography for the scenario and each BMP. This geography may include the entire county or just the portion that drains to the Chesapeake Bay Watershed, denoted as CBWS-only. Acres shown in the pre-BMP load source table are those in the geography selected when the scenario was created.

Why doesn’t the cost change when I change the total amount implemented?

The cost shown is the annualized cost per unit. That means that the cost is for one year of implementation (annualized) and is for a single unit of implementation, commonly acres or acres treated.

Manure Treatment BMPs

Why am I getting an error whenever I try to add this BMP?

If you get an error message that a BMP cannot be added, it is likely already added in units of percent. You may edit the amount of implementation in that table, or edit the BMP to change the amount or percent to avoid the conflict. BMPs entered as percents cannot be entered on the same or overlapping geographies and animal types, but BMPs entered as number of animals can overlap geographies and load sources. An example of an overlapping geography is a county and a state. An example of overlapping animal types are poultry and broilers because poultry includes broilers.

How can I sort the tables on the BMP pages?

Tables occur in multiple pages throughout. The default sorting is indicated by the highlighted column, with an arrow pointing up for ascending and down for descending. Sorting may be changed by clicking on that and any other column. Clicking once reverses the order. Clicking twice removes sorting from the column. Clicking on another column will move sorting to that column.

How do I filter tables on the BMP pages?

Records may be selected by using the filter option. There are multiple options for how to filter, and these options work the same as excel or most other applications with filtering capacity.

The BMP names we use don't match those used by the Chesapeake Bay Program. How do I know which BMP to select?

A cross-walk of commonly used BMP names to Chesapeake Bay Program BMP names is available on the Home page under BMPs. This cross walk includes NRCS practice names. Note that only one BMP should be entered where there are multiple BMPs treating the same area, such as occurs with a treatment train. Select the BMP that is dominant.

Why do I have to enter geographic scale on this BMP page when I defined it for the scenario? What if I pick state for a BMP, but defined the entire scenario as county?

The geographic scale may be different than the scale at which the scenario was created. Where a geographic area for a BMP is selected as larger than that of the scenario, then the load estimates will show only the loads for the area of the scenario, even though the BMP was applied to a larger area. That is, the user will not see the load reduction for the area outside of the scenario-defined boundary. The reduction will be parsed to the entire area specified by the BMP, even if your scenario was defined as something smaller.

Why can't I edit the BMP cost?

Cost components may be edited on the costs page. The BMP pages and results pages will update with the new cost once you reselect it under scenario details.

Why doesn't the cost change when I change the total amount implemented?

The cost shown is the annualized cost per unit. That means that the cost is for one year of implementation (annualized) and is for a single unit of implementation, commonly acres or acres treated.

What do I do if I don't know the destination of manure transported?

Manure transport requires a source location and a destination location. Either the source or destination of the manure may be out of the Chesapeake Bay watershed.

Why can't I enter the amount of manure transported for anything but the county scale?

Manure transport is only at the scale of the entire county. It is not possible to transport manure from a smaller area. This is because manure data is only available for the county and estimates of loading rates are not available at a scale smaller than a county.

How is Manure Treatment Technology credited differently than Manure Transport? What is the difference between all 19 different types of Manure Treatment Technology?

Manure transport simply moves the manure from one location to another and then the replacement nutrients are applied in the source location. Manure Treatment Technology works the same way but also includes a reduction based on the treatment and an added load due to ammonia volatilization. A reference guide is available that discusses the types of Manure Treatment Technology. It may be downloaded from the CAST home page under BMPs, Models and Geography. The direct link is: https://www.chesapeakebay.net/documents/BMP-Guide_Full.pdf. The information for this BMP is on pages 68 to 75.

What level of N and P load reductions are achieved for removing a ton of manure from the watershed?

This amount is highly variable and depends on the number and type of animals in a county, crop need, and acres of manure-receiving land uses. For nitrogen, the load is likely to increase with additional implementation of Manure Transport and Manure Treatment Technologies. An estimate of the load reduction by BMP is available for all counties for nitrogen as well as phosphorus by downloading the spreadsheet named BMP Pounds Reduced and Costs under the heading Cost Effectiveness of BMPs at: http://cast.chesapeakebay.net/Documentation/DevelopPlans. An average for PA is 0.43 pounds of phosphorus per dry ton of manure.

The difference in nutrient concentrations by animal types may be found in the manure source data file that can be downloaded from: http://cast.chesapeakebay.net/Home/SourceData. It varies by year, county and animal type.

What is the different effect of transporting manure between counties compared to moving manure out of the watershed?

Manure transport between counties reduces the manure in the source county and increases it in the destination county. The biggest load reduction comes from reducing crop need with the Nutrient Management Core BMP. If your area of interest is only the source county, then moving to another county or out of the watershed accomplishes the same goal. If you are looking at managing a larger area, like a state, then phosphorus reductions can be seen from manure transport. The impact depends on multiple factors like crop need, amount of manure, acres of cropland, and other BMPs in the scenario.

How can I determine which counties have manure in excess of crop need?

Login to CAST and navigate to Results>Reports. Select the report type of Nutrients Applied. You can request the report for multiple counties for a scenario. This report includes the amount of manure and fertilizer applied to meet the crop need. There are columns with the amount of crop need, manure and fertilizer. Note that eliminating manure does not bring the loads down. You also must reduce the crop need using the Nutrient Management Core BMP. You can see the amount of crop need met in this same report in the column named Total N App to Crop Need. Implementing 100% of Nutrient Management Core will produce the lowest crop need.

Is there a reduction in N and P for eliminating manure from a county that does not have excess manure nutrients?

There is likely to be a phosphorus reduction since manure is applied to meet the nitrogen crop need. It is less likely that there is a nitrogen reduction since the replacement nutrients are applied at the same application rate as before the manure was eliminated.

Why did my nitrogen loads increase with Manure Treatment Technology or Manure Transport?

While phosphorus will be reduced after applying the Manure Treatment Technology or Manure Transport BMP, nitrogen loads may increase. Removing manure without also controlling the amount of replacement inorganic fertilizer results in the same rate of inorganic fertilizer being applied as when manure was applied. When using these manure BMPs, increase the amount of the Nutrient Management Core BMP (accessed in the Agriculture BMPs tab) to control the amount of replacement inorganic fertilizer. Additionally, the runoff of inorganic fertilizer is higher than manure, which also contributes to the potential increase in nitrogen loads.

The Nutrient Management Core BMP will lower the application to the crops. It is recommended that this be implemented on most, if not all, of the acres. The other Nutrient Management BMPs for Rate, Placement, and Timing reduce the amount of runoff loads but do not affect the crop need or application rate.

Here is more detail on how the application rate is determined. The amount of nitrogen and phosphorus crop need met is defined by the amount met in 2014. The nitrogen and phosphorus nutrients are applied to agricultural load sources using the fraction of crop need met in that year's progress. If the amount of crop need met in 2014 was 110%, then 110% of crop need will be met in 2015 and later years. When selecting base conditions for years between 1984 and 2014, the amount of crop need calculated from the ratio of all nutrient inputs applied to meet crop need are defined by the official annual progress scenario for that year.

Why are there changes in N and P loads on non-manured load sources when I implement Manure Treatment Technology or Manure Transport? Shouldn’t this only change the agricultural load sources that receive manure?

One of the parameters used to calculate the phosphorus loads is the amount of phosphorus in the soil. That is calculated across all crop load sources together, following the decision of the Chesapeake Bay Program Partnership. When manure is changed, such as with the manure transport BMP, the impact will be on all crop load sources, not just those that have manure applications. The non-manured load sources that show this change are soybeans, grains without manure, and silage without manure.

When comparing the phosphorus loads among years, I am seeing the loads change in an unexpected direction. Why?

This can happen for several reasons related to BMP implementation levels. Phosphorus loads can be amplified when Manure Treatment Technology or Manure Transport are decreased in later years than in the prior year. The amount of manure available in 2014 was part of the calculation of crop need that is met. Decreasing Manure Treatment Technology and/or Manure Transport BMPs will increase the amount of manure. The manure that previously was transported will be applied in addition to the manure and fertilizer application that meets crop need. Put another way, for phosphorus, the difference between the amount of Manure Transport in 2014 and later years is subtracted from the amount of manure nutrients applied after other nutrients are applied to meet the proportion of crop need met in 2014. The implication is that if more manure is transported into a location than was transported out in the 2014 Progress, the phosphorus applied is effectively lowered. Conversely, if less manure is transported out of a location than was transported in for the 2014 Progress, the phosphorus applied increases.

What level of N and P load reductions are achieved for removing a ton of manure from the watershed?

This amount is highly variable and depends on the number and type of animals in a county, crop need, and acres of manure-receiving land uses. For nitrogen, the load is likely to increase with additional implementation of Manure Transport and Manure Treatment Technologies. An estimate of the load reduction by BMP is available for all counties for nitrogen as well as phosphorus by downloading the spreadsheet named BMP Pounds Reduced and Costs under the heading Cost Effectiveness of BMPs at: http://cast.chesapeakebay.net/Documentation/DevelopPlans. An average for PA is 0.43 pounds of phosphorus per dry ton of manure. The biggest load reduction comes from reducing crop need with the Nutrient Management Core BMP. 

Where can I find information on the difference in nutrient concentrations by animal types?

The difference in nutrient concentrations by animal types may be found in the manure source data file that can be downloaded from: http://cast.chesapeakebay.net/Home/SourceData. It varies by year, county and animal type.

What is crop need?

Crop need is the amount of nutrients a crop is designated to need to produce a typical crop yield.

How is the nutrient application rate determined for the crop need?

The amount of nitrogen and phosphorus crop need met is defined by the amount met in 2014. The nitrogen and phosphorus nutrients are applied to agricultural load sources using the fraction of crop need met in that year's progress. If the amount of crop need met in 2014 was 110%, then 110% of crop need will be met in 2015 and later years. When selecting base conditions for years between 1984 and 2014, the amount of crop need calculated from the ratio of all nutrient inputs applied to meet crop need are defined by the official annual progress scenario for that year.

How do I lower the nutrient application rate?

The Nutrient Management Core BMP will lower the application to the crops. It is recommended that this be implemented on most, if not all, of the acres. The other Nutrient Management BMPs for Rate, Placement, and Timing reduce the amount of runoff loads but do not affect the crop need or application rate.

Why are there changes in N and P loads on non-manured load sources when I implement Manure Treatment Technology or Manure Transport? Shouldn't this only change the agricultural load sources that receive manure?

One of the parameters used to calculate the phosphorus loads is the amount of phosphorus in the soil. That is calculated across all crop load sources together, following the decision of the Chesapeake Bay Program Partnership. When manure is changed, such as with the manure transport BMP, the impact will be on all crop load sources, not just those that have manure applications. The non-manured load sources that show this change are soybeans, grains without manure, and silage without manure.