Find answers to your questions regarding the transition to Phase 6 of the Chesapeake Bay Partnership's Modeling Tools.

Transition To Phase 6 FAQs

Why will CAST and BayFAST be transitioning to Phase 6?

The Models are used to assess progress toward the 2010 Chesapeake Bay Total Maximum Daily Load (Bay TMDL) for nitrogen, phosphorus and sediment. The Bay TMDL calls for an assessment in 2017 to review our progress toward meeting the nutrient and sediment pollutant load reductions identified in the 2010 Bay TMDL, Phase I and Phase II Watershed Implementation Plans (WIPs) and two-year milestones. Incorporating the new scientific findings and data will improve the midpoint assessment progress tracking. While the CAST suite of models were developed primarily for the WIPs and Milestones, it is recognized that they serve to help planners achieve water quality Improvements for a multitude of purposes, including local TMDLs. The updates will improve all planning efforts.

How will CAST and BayFAST change to conform to Phase 6?

There are several changes planned in the structure of the models between Phase 5.3.2 and Phase 6. In Phase 6, all of the loads will be identical between CAST, Scenario Builder and the Watershed Model because the calculation engine will be the same-only the interfaces will be different. With this unification of all the modeling tools, MAST and VAST will be replaced by CAST. There will be no loss in functionality. BayFAST will continue as the site-specific planning tool.

What new features will be in the Phase 6 versions of the tools?

New functionality will include uploading BMP files as a batch, editing all data directly in tables on the screen as well as adding through the web form. More information about lowest cost pollution reduction strategies also will be available. Plans are underway to develop an optimization module. This module will allow the user to input objectives, then loads and the optimal set of BMPs will be returned. BMP co-benefits, such as those related to habitat, are planned to be returned as well. Data visualization is added so users can see the differences among scenarios in graphs and maps. Data available through CAST and BayFAST includes nitrogen, phosphorus, and sediment loads from official scenarios as well as user-defined scenarios. Initial conditions by year for load sources, animals, and septics also will continue to be available. Reference data including land use definitions, BMP definitions, BMP effectiveness, geographic references, and delivery factors also are available. As with the current version, this information is available without a log in.

Download Source Data

What other features will be different in Phase 6 compared with Phase 5.3.2?

Other 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. The new version will have 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 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.

When will CAST and BayFAST be transitioning to Phase 6?

CAST was available in draft final form June 15, 2017 for review along with calibration model output, which was available June 1, 2017. The transition to CAST 2017, the final Phase 6 version, is expected to occur in the fall of 2017. This is in advance of Phase III WIP development and after the Phase 6 models are reviewed and released by the Partnership. BayFAST development will occur once the final version of CAST is released in the fall.

How will online access to CAST and BayFAST change?

The site addresses are changing. There will be a link to the new address on the current CAST and BayFAST sites. Once redirected to the Phase 6 tools, users will need to create new login information. Password requirements will follow Federal Information Security Management Act (FISMA) Standards. This will require more secure password requirements such as updating your password every 60 days with no reuse within 24 passwords. User names automatically will be the email you used to register your account. As with the current version of CAST and BayFAST, assistance is available if you have forgotten logins, passwords or the email used to create the account.

What will happen to the current versions of the tools?

The old version of CAST and BayFAST will accept no new facilities, scenarios or changes to inputs after Spring 2018. Users can download facility and scenario data, then upload it to the Phase 6 CAST or BayFAST. Differences in the model versions require users to modify BMPs and the load sources to which they are applied. Modifications can vary depending on your intention. Each user has to determine what makes sense in the context of their scenarios. Guidance on assigning new land uses and substituting BMPs will be provided. These data can then be uploaded in batch form to Phase 6 tools.

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 is 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

What is the file format for uploading BMPs?

The Phase 6 version of CAST allows BMPs to be uploaded from a file. Uploaded BMPs are tab-delimited text files. Tables below show the list of required columns and sample data for the files. More information is available in the word document.

Uploading BMPs to CAST

Sample Land BMPs

Sample Animal BMPs

Sample Manure BMPs

How do I transition scenarios from to  CAST-2017?

CAST users who want to use prior CAST scenarios in the new CAST-2017 will need to transition their scenarios. Differences in the model versions require users to modify BMP data. Modifications can vary depending on your intention. The downloadable document and spreadsheet provides suggestions on how to relate the old BMP data to valid CAST-2017 data. The suggestions are provided only as a starting point or example for CAST users.

Tips for transitioning Phase 5 scenarios to CAST

CAST Version Relationship Tables