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Missisquoi Bay Basin CSA Maps and Data
Under contract from LCBP, Stone Environmental, Inc. conducted complex computer modeling to develop detailed information about the distribution of potential Critical Source Areas (CSAs) of phosphorus to Missisquoi Bay. The project was conducted to address a 2008 reference to the International Joint Commission (IJC) by the governments of the United States and Canada to coordinate initiatives in both countries to reduce phosphorus loading to the bay. Critical Source Areas are areas of the landscape that, absent proper management, are likely to produce disproportionate amount of phosphorus and sediment pollution. Areas shown as potential CSAs were identified primarily by their soils, landscape features, proximity and connectivity to streams, and the land use or farm crop practices that are in place or are likely to be in place.
Current and detailed information about existing agricultural Best Management Practices (BMPs) was not available to the study, and so is not included in the analysis. Because management practices are constantly changing and old or outdated information could inadvertently bias model results, it is not practical to account for BMPs in the modeling process. It is important to note that many farmers have already established BMPs in these areas, controlling or reducing the export of phosphorus to adjacent streams.
In addition, all models generalize, and include a small percentage of errors. That is why even with a very high level of accuracy, there still will be areas shown as potential CSAs in error.
What the CSA map is not good for:
This CSA map is not suitable for use in any way as an enforcement tool because of the possibility of errors and the likelihood that many areas identified already have had best management practices applied to reduce phosphorus export.
What the CSA map is good for:
This CSA map is a useful tool for:
- Informing landowners about the locations on their property with a high likelihood of excess phosphorus in the soil, and an apparently easy route for that phosphorus to be discharged into a tributary stream.
- Identifying likely Critical Areas so that property owners know where to plan (or maintain existing) best management practices to protect water quality.
- Guiding resource allocations by management agencies to those critical areas in need of financial and technical assistance, to reduce the movement of phosphorus into adjacent waterways.
The LCBP thanks the many farmers in the Missisquoi Bay watershed who volunteered information about their farming practices and contributed to the accuracy of this phosphorus Critical Source Area study.
Stone Environmental’s Final Report (LCBP Technical Report #63b) provides important information about how the Phosphorus Critical Source Area maps were developed and how to interpret them.