The most recent meeting of the Potomac Watershed Roundtable was in Warrenton, VA at Lord Fairfax Community College and had a series of speakers on the Chesapeake Bay strict pollution diet, the Total Maximum Daily Load (TMDL) mandated by the EPA to the six Chesapeake Bay Watershed states and the District of the Columbia. The TMDLs were assigned by the EPA to each segment of the Chesapeake Bay Watershed. For the TMDL, the Chesapeake Bay’s tidal waters have been divided into 92 tidal water segments. There are 35 segments controlled by Virginia and another five Maryland owned segments that include Virginia drainage areas. The different water segments are determined by their varying degrees of salinity, recalling that the Chesapeake Bay Watershed is an estuary. Finally, the TMDLs address only pollution from excess nitrogen, phosphorus and sediment. No action has been taken on other pollutants that might be present in the Chesapeake Bay and its tributaries.
On November 29th 2010 Virginia, submitted the final version of the Virginia Chesapeake Bay Watershed Implementation Plan (WIP) to the U.S. Environmental Protection Agency and December 29th the EPA accepted the revised version of Virginia’s WIP and issued the “final” TMDL, but with “enhanced oversight.” (Doesn’t that sound like fun.) The TMDLs were created by a series of models of the Chesapeake Bay Watershed that include various land use models, water quality models and watershed models. These computer models are mathematical representations of the real world that estimate environmental events and conditions. The models are at best imperfect, but they are nonetheless the best tool available to view the 64,000 square miles of the watershed. The Chesapeake Bay and its watershed are so large and complex, that scientists and regulators rely on computer models for critical information about the ecosystem’s characteristics and the impact of various environmental actions to reduce pollution. It is possible that they have been spending a wee bit too much time looking at computer output and missed the big picture.
Mike Rolband, President of Wetland Studies and Solutions, Inc. had an interesting presentation pointing out poor model behavior, mistakes and injustices of the current TMDL, what EPA has called the strict pollution diet, but really is an excess nutrient diet. When Mike showed the group his slides, several aspects of the Chesapeake Bay Watershed, the EPA’s models, the mandated TMDLs became very clear for me. First of all, the level of excess nutrients in each of the major tributaries to the Chesapeake Bay is fairly well known and well predicted and calibrated by the models. Second, this is indeed a diet, the Chesapeake Bay is overwhelmed with excess nutrients and sediment, and like an obese person, less nutrients will improve the situation. Thirdly, land use and population density matter, but generally the higher the population the more total nutrients are released. Waste water treatment plants and urban runoff and septic contribute a larger load of nitrogen than the agricultural sector. Finally, the EPA mandated TMDL and the approved WIPs to implement them require a percentage reduction in nutrient load from each sector.
This turns out to be vastly inequitable. Eliminating the agricultural sector, Northern Virginia with 46% of the watershed population is required to obtain a total nitrogen load for the waste water treatment plants, urban and septic of 2.52 pounds of nitrogen/person/year while the James River Basin is only required to obtain 6.38 pounds of nitrogen/person/year and the state target average is 4.43 pounds of nitrogen/person/year. This is the equivalent of mandating a diet for everyone in Virginia to lose 1/3 of their body weight. This might be just fine and actually beneficial for the 300 pound people who will be forced to lose 100 pounds, but it is lethal for the 150 pound Potomac Watershed that will have to loose 50 pounds each. We in northern Virginia are trapped in some Kafka version of a diet where slow death by starvation (stopping population growth and potentially reducing population) may be the unintended consequences of the EPA mandated pollution diet.
Showing posts with label Potomac Watershed Roundtable. Show all posts
Showing posts with label Potomac Watershed Roundtable. Show all posts
Monday, January 31, 2011
Monday, January 17, 2011
The Chesapeake Bay Model
The most recent meeting of the Potomac Watershed Roundtable was in Warrenton, VA at Lord Fairfax Community College and had a series of speakers on the Chesapeake Bay strict pollution diet, the Total Maximum Daily Load (TMDL) mandated by the EPA to the six Chesapeake Bay Watershed states and the District of the Columbia. The TMDL addresses only pollution from excess nitrogen, phosphorus and sediment. No action has been taken or at this time is intended on other pollutants that might be present in the Chesapeake Bay and its tributaries. Two of the speakers, walked the Roundtable audience through some of the issues and uncertainties will impact implementing a plan to achieve the TMDLs on the local level.
Clifton Bell of Malcolm Pirnie, Inc. and Mike Rolband of Wetland Studies and Solutions, Inc. walked the group through some of the issues with the EPA “final” TMDL loading levels and how they were obtained. The TMDLs were created by a series of models of the Chesapeake Bay Watershed that include various land use models, water quality models and watershed models. These computer models are mathematical representations of the real world that estimate environmental events and conditions. The models are at best imperfect, but they are nonetheless the best tool available to view the 64,000 square miles of the watershed. The Chesapeake Bay and its watershed are so large and complex, that scientists and regulators rely on computer models for critical information about the ecosystem’s characteristics and the impact of various environmental actions to reduce pollution. Mr. Bell lifted the curtain to point out some aspects of the models.
Although model simulations are an important part of the Chesapeake Bay regulatory mandate, they are not considered by the EPA to be perfect forecasts. Rather, model simulations are the current best estimates. The Chesapeake Bay Model is really made up of several models that are added together to create the whole: the Watershed Model, the Estuary Model, the Scenario Builder, the Airshed Model, the Land Change Model and the Land Use Models.
The Watershed Model incorporates information about land use, fertilizer applications, wastewater plant discharges, septic systems, air pollution, farm animal populations, weather and other variables to estimate the amount of nutrients and sediment reaching the Chesapeake Bay and which of the major land uses produce these pollutants. This is the most robust and calibrated portion of the model sequence because it is calibrated and validated on the major tributary basin levels where there is decades of measured water quality data available. The Watershed Model divides the 64,000-square-mile Chesapeake Bay watershed into more than 2,000 segments.
The Estuary Model examines the effects that pollution loads generated by the Watershed Model have on water quality. In the Estuary Model, the Chesapeake Bay is further divided into more than 57,000 computational cells and is built on two sub-models: The hydrodynamic sub-model and the water quality sub-model. The water quality sub-model is well calibrated for dissolved oxygen.. However, it is unclear that dividing up the world in ever smaller pieces gives you better resolution when there are not enough hard data points in the cells. Zooming in on a picture without adequate pixels does not increase the resolution.
The Scenario Builder can generate simulations of the past, present or future state of the Chesapeake Bay watershed to explore potential impacts of regulation and management actions and evaluate alternatives. This model creates the assumptions in the regulated community much like Sims game.
The Airshed Model uses information about nitrogen emissions from power plants, vehicles and other sources to estimate the amount of and location where these pollutants are deposited on the Chesapeake Bay and its watershed using information from vehicle registrations and DOT and weather.
The Land Change Model analyzes and forecasts the effects of urban land use and population on sewer and septic systems in the Chesapeake Bay watershed based on: population trends and forecasts, migration, satellite imagery, and waste water treatment plant service area and data. Finally, the Land Use model estimates the types and amounts of pollution that run off a particular land use are based on comprehensive reviews of the latest scientific literature.
Since most of the models were built and calibrated on the data that has been collected over the years they are well calibrated on the major tributaries and basins where most of the sampling and research has been done. The models are designed conservatively; all waste water treatment plants are assumed to discharge their maximum load simultaneously. The best management practices, BMPs, used to manage stormwater and runoff are assumed to be effective only at the low end of their effectiveness range.
In addition, according to Mr. Bell, the model was never designed to be accurate on the local level and this was confirmed in 2008 when the Scientific and Technical Advisory Committee, STAC, Peer Review recommended that the model not be used for local TMDLs. Nonetheless, that is exactly what the EPA did. The models reportedly produce some non-intuitive trends, poorly calibrated results and poor model behavior raising the question of whether the regulatory scheme relies too heavily on the model and will distort desired behavior. They have created a situation where base assumptions are based on the model’s presentation of reality and management practices are not selected for the cost and measured improvement on water quality or ease to maintain, but rather the impact these steps have on model results.
Clifton Bell of Malcolm Pirnie, Inc. and Mike Rolband of Wetland Studies and Solutions, Inc. walked the group through some of the issues with the EPA “final” TMDL loading levels and how they were obtained. The TMDLs were created by a series of models of the Chesapeake Bay Watershed that include various land use models, water quality models and watershed models. These computer models are mathematical representations of the real world that estimate environmental events and conditions. The models are at best imperfect, but they are nonetheless the best tool available to view the 64,000 square miles of the watershed. The Chesapeake Bay and its watershed are so large and complex, that scientists and regulators rely on computer models for critical information about the ecosystem’s characteristics and the impact of various environmental actions to reduce pollution. Mr. Bell lifted the curtain to point out some aspects of the models.
Although model simulations are an important part of the Chesapeake Bay regulatory mandate, they are not considered by the EPA to be perfect forecasts. Rather, model simulations are the current best estimates. The Chesapeake Bay Model is really made up of several models that are added together to create the whole: the Watershed Model, the Estuary Model, the Scenario Builder, the Airshed Model, the Land Change Model and the Land Use Models.
The Watershed Model incorporates information about land use, fertilizer applications, wastewater plant discharges, septic systems, air pollution, farm animal populations, weather and other variables to estimate the amount of nutrients and sediment reaching the Chesapeake Bay and which of the major land uses produce these pollutants. This is the most robust and calibrated portion of the model sequence because it is calibrated and validated on the major tributary basin levels where there is decades of measured water quality data available. The Watershed Model divides the 64,000-square-mile Chesapeake Bay watershed into more than 2,000 segments.
The Estuary Model examines the effects that pollution loads generated by the Watershed Model have on water quality. In the Estuary Model, the Chesapeake Bay is further divided into more than 57,000 computational cells and is built on two sub-models: The hydrodynamic sub-model and the water quality sub-model. The water quality sub-model is well calibrated for dissolved oxygen.. However, it is unclear that dividing up the world in ever smaller pieces gives you better resolution when there are not enough hard data points in the cells. Zooming in on a picture without adequate pixels does not increase the resolution.
The Scenario Builder can generate simulations of the past, present or future state of the Chesapeake Bay watershed to explore potential impacts of regulation and management actions and evaluate alternatives. This model creates the assumptions in the regulated community much like Sims game.
The Airshed Model uses information about nitrogen emissions from power plants, vehicles and other sources to estimate the amount of and location where these pollutants are deposited on the Chesapeake Bay and its watershed using information from vehicle registrations and DOT and weather.
The Land Change Model analyzes and forecasts the effects of urban land use and population on sewer and septic systems in the Chesapeake Bay watershed based on: population trends and forecasts, migration, satellite imagery, and waste water treatment plant service area and data. Finally, the Land Use model estimates the types and amounts of pollution that run off a particular land use are based on comprehensive reviews of the latest scientific literature.
Since most of the models were built and calibrated on the data that has been collected over the years they are well calibrated on the major tributaries and basins where most of the sampling and research has been done. The models are designed conservatively; all waste water treatment plants are assumed to discharge their maximum load simultaneously. The best management practices, BMPs, used to manage stormwater and runoff are assumed to be effective only at the low end of their effectiveness range.
In addition, according to Mr. Bell, the model was never designed to be accurate on the local level and this was confirmed in 2008 when the Scientific and Technical Advisory Committee, STAC, Peer Review recommended that the model not be used for local TMDLs. Nonetheless, that is exactly what the EPA did. The models reportedly produce some non-intuitive trends, poorly calibrated results and poor model behavior raising the question of whether the regulatory scheme relies too heavily on the model and will distort desired behavior. They have created a situation where base assumptions are based on the model’s presentation of reality and management practices are not selected for the cost and measured improvement on water quality or ease to maintain, but rather the impact these steps have on model results.
Thursday, January 13, 2011
Potomac Watershed Roundtable Meeting:The Chesapeake Bay, the Virginia Watershed Implementation Plan, and the EPA mandated TMDL
The most recent meeting of the Potomac Watershed Roundtable was in Warrenton, VA at Lord Fairfax Community College and had a series of speakers on the Chesapeake Bay strict pollution diet, the Total Maximum Daily Load (TMDL) mandated by the EPA to the six Chesapeake Bay Watershed states and the District of the Columbia. The TMDL addresses only pollution from excess nitrogen, phosphorus and sediment. No action has been taken on other pollutants that might be present in the Chesapeake Bay and its tributaries.
On November 29th 2010 Virginia, submitted the final version of the Virginia Chesapeake Bay Watershed Implementation Plan (WIP) to the U.S. Environmental Protection Agency. The introduction to the revised plan states that full implementation of the plan would cost more than $7 billion dollars the WIP went on to state that “In these austere times, we cannot guarantee what additional funding will be provided by our General Assembly. It is our position that the success of the WIP may be subject to the provision of sufficient federal funding to assist in covering these massive new unfunded mandates.”
If you recall the first version of the Virginia WIP the plan did not meet the TMDL loading levels with “reasonable assurance.” On December 29th the EPA accepted the revised version of Virginia’s WIP and issued the “final” TMDL, but Virginia will have enhanced oversight. The January 7th 2011 meeting of the Potomac Roundtable addressed the next steps for the counties and towns in the Potomac Watershed. Russ Baxter, from the Virginia Department of Environment Quality, DEQ, closed the meeting with the State’s perspective and issues facing the state and local governments in implementing the WIP. I found Mr. Baxter’s perspective to be very enlightening and so I share some of his points.
Mr. Baxter was emphatic that the WIP is a living document intended to attain the TMDL and contains proposed management action among the sectors of the Chesapeake Bay Watershed that are the source of nutrient contamination to the Bay. The WIP is designed not only to satisfy the demands of the Federal regulators but to allow flexibility to the local governments in implementation to allow them to use the most cost effective approach to achieve the TMDL goals. Also, Mr. Baxter acknowledged that the septic portion of the WIP read like a limitation on developing new housing in the region, but that was not intended to happen.
When the Chesapeake Bay Model is revised to correct know deficiencies in the near future the TMDLs mandated to Virginia and the other states and DC will be revised and the Phase II of the WIP will have to be developed to reflect these changes. Though, the Phase II WIPs are supposed to be due in 2011, EPA has yet to notify the states and DC of the changes and in reality it is unlikely that the changes will be available before the annual Virginia Legislative session. Mr. Baxter pointed out that the WIP is intended to achieve the current 2017 check points with “reasonable assurances” and achieve a restored Bay by 2025. We know what direction we are heading in and can start this leg of the journey, making course corrections as we go.
The Potomac Watershed Roundtable was founded in 2000 and serves as a regional government-citizen forum to collaborate and cooperate on environmental issues among the various local government and stakeholder groups of nine counties, six towns and cities, the six soil and water conservation districts and various stakeholders including interested citizens.
On November 29th 2010 Virginia, submitted the final version of the Virginia Chesapeake Bay Watershed Implementation Plan (WIP) to the U.S. Environmental Protection Agency. The introduction to the revised plan states that full implementation of the plan would cost more than $7 billion dollars the WIP went on to state that “In these austere times, we cannot guarantee what additional funding will be provided by our General Assembly. It is our position that the success of the WIP may be subject to the provision of sufficient federal funding to assist in covering these massive new unfunded mandates.”
If you recall the first version of the Virginia WIP the plan did not meet the TMDL loading levels with “reasonable assurance.” On December 29th the EPA accepted the revised version of Virginia’s WIP and issued the “final” TMDL, but Virginia will have enhanced oversight. The January 7th 2011 meeting of the Potomac Roundtable addressed the next steps for the counties and towns in the Potomac Watershed. Russ Baxter, from the Virginia Department of Environment Quality, DEQ, closed the meeting with the State’s perspective and issues facing the state and local governments in implementing the WIP. I found Mr. Baxter’s perspective to be very enlightening and so I share some of his points.
Mr. Baxter was emphatic that the WIP is a living document intended to attain the TMDL and contains proposed management action among the sectors of the Chesapeake Bay Watershed that are the source of nutrient contamination to the Bay. The WIP is designed not only to satisfy the demands of the Federal regulators but to allow flexibility to the local governments in implementation to allow them to use the most cost effective approach to achieve the TMDL goals. Also, Mr. Baxter acknowledged that the septic portion of the WIP read like a limitation on developing new housing in the region, but that was not intended to happen.
When the Chesapeake Bay Model is revised to correct know deficiencies in the near future the TMDLs mandated to Virginia and the other states and DC will be revised and the Phase II of the WIP will have to be developed to reflect these changes. Though, the Phase II WIPs are supposed to be due in 2011, EPA has yet to notify the states and DC of the changes and in reality it is unlikely that the changes will be available before the annual Virginia Legislative session. Mr. Baxter pointed out that the WIP is intended to achieve the current 2017 check points with “reasonable assurances” and achieve a restored Bay by 2025. We know what direction we are heading in and can start this leg of the journey, making course corrections as we go.
The Potomac Watershed Roundtable was founded in 2000 and serves as a regional government-citizen forum to collaborate and cooperate on environmental issues among the various local government and stakeholder groups of nine counties, six towns and cities, the six soil and water conservation districts and various stakeholders including interested citizens.
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