Karl Blankenship, Editor of the Chesapeake Bay Journal, recently did a comprehensive article examining the issues related to the Chesapeake Bay Program’s midpoint assessment and whether states are meeting their sediment and nutrient reduction targets.
Here is just a small part of the article. Click Here to read the entire article.
Take one Conowingo Dam, sprinkle it with a bit of climate change, mix in an unhealthy amount of phosphorus-saturated soil and you could have the recipe for a big Bay headache.
Those are some of the major science and policy issues that local, state and federal officials are grappling with as they take stock of where Chesapeake Bay cleanup efforts stand with the halfway mark approaching in the agreed-upon timetable for reaching restoration goals.
For several years now, officials have been preparing for what’s known as the “midpoint assessment,” mulling over new science, monitoring data, land use and other local information to gauge the effectiveness of actions taken to date.
And perhaps even more importantly, they’re trying to understand what’s changed since the latest Bay cleanup goal was set in 2010.
The goal of the assessment, slated for completion next year, is to use all available new information to make whatever adjustments are needed to complete the multi-billion dollar restoration effort by its 2025 deadline.
Based on the results, states and the federal agencies will need to revise their strategies for delivering a healthy Bay for the public — as well as for the crabs, fish, underwater grasses and even bottom-dwelling worms that depend on it.
The good news is that a wealth of new information is providing a clearer-then-ever picture of where pollution is coming from and how it’s affecting the nation’s largest estuary.
On the other hand, that information, when melded together, is likely to show that meeting nitrogen, phosphorus and sediment reduction goals by 2025 will be a more daunting task than what was envisioned just a few years ago.
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The assessment’s outcome will set the stage for tough policy debates among the EPA and the states. New information could make the cleanup job substantially more difficult — perhaps impossible — for some agricultural areas with phosphorus-saturated soils. Pennsylvania, which is already significantly lagging in its efforts, could face additional burdens related to the Conowingo issue.
Among the questions that could arise: Would other areas, sectors or states be able or willing to take on more of the pollution-reduction burden? Conversely, would states or federal agencies be willing to send more money or resources to problematic areas?
“I think they would be tough conversations to have, but I think we are going to have to have them,” said Beth McGee, senior water quality scientist with the Chesapeake Bay Foundation.
An even more difficult question: If the changes show the cleanup effort is more difficult, will Bay water quality goals actually be attainable?
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Key Issues In The Midpoint Assessment
Here’s a look at some of the key issues in the midpoint assessment:
-- Conowingo Dam: Scientists have long warned that one day the reservoir behind the Conowingo Dam on the Susquehanna River was filling with sediment, and as that happens, more nutrients and sediment pass through the dam and enter the Bay. But when the Chesapeake Bay Total Maximum Daily Load was completed in 2010, it wasn’t recognized that the reservoir had essentially already reached its storage capacity and the flow of nutrients had already increased.
A recent U.S. Army Corps of Engineers report said that offsetting the lost pollution-trapping impact of Conowingo Dam could require 2.4 million additional pounds of nitrogen reductions and 270,000 pounds of additional phosphorus reductions from the Susquehanna River.
Those are reductions that were not factored into the TMDL. Not only are they extra nutrients that have to be controlled, but they are coming from the worst possible place: the Susquehanna. Pound-for-pound, nutrients from the river have a greater impact on dissolved oxygen levels in the deep-water areas of the upper Bay — the area which has the greatest problem meeting water quality standards — than nutrients from other rivers.
Computer modeling shows that if those nutrient reductions don’t come from the Susquehanna, other portions of the Bay watershed would have to cut back by nearly twice as much — 4.4 million pounds of nitrogen and 410,000 pounds of phosphorus — to achieve the same water quality benefit.
Factor in that Pennsylvania, which contributes the lion’s share of the Susquehanna’s nutrients, is already tasked with the greatest reduction burden of any state and is far behind schedule in meeting its goals, and the stage is set for a difficult policy debate, probably next year.
-- Climate Change: Water in the Bay and its tributary rivers is warming; Chesapeake water levels are rising; and the frequency and severity of storms have been increasing. All of that can affect the amount of nutrients and sediment washing off the land and how they affect water quality.
The interactions are complex: Higher sea levels can draw more ocean water into the Bay and cause more water mixing — which is generally a good thing — but they can also erode shorelines and buffering marshes. Warmer water tends to hold less oxygen than cooler water and threatens the survival of ecologically vital eelgrass in the Lower Bay.
On balance, scientists and officials believe such changes will ultimately make the Bay cleanup more difficult. Key questions: How rapidly will they occur, and will they have an impact by 2025, or sometime later?
At the least, the issue could force a re-examination of some of the best management practices being installed, as well as how to maintain their effectiveness in decades to come. For instance, stormwater and some farm runoff controls may need to be designed to withstand larger, more frequent storms. Building so-called “living shorelines” may become more important in managing erosion and protecting marshes.
-- Phosphorus: In the past, the Bay Program’s watershed model assumed that the amount of phosphorus that runs off farmland was related to the amount that is applied. But research has shown that in areas where phosphorus levels have built up in soils over many decades, the nutrient continues to leak out even if little or none is spread on fields.
That may help explain why the model shows phosphorus levels going down in some places where water quality monitoring shows worsening trends. A new sub-model is being developed in cooperation with land grant universities and the U.S. Department of Agriculture to better account for the phosphorus buildup in soils. Once completed, it’s likely to discount at least some of the phosphorus reductions previously estimated by the model.
The EPA last year warned states of that likely change, saying the agency “believes that the level of effort to manage phosphorus may increase” and states should “consider additional actions to manage phosphorus” in the future.
-- Best Management Practices: In the past, the Bay Program only counted a few dozen best management practices, or BMPs, toward meeting nutrient and sediment reduction goals. In the last few years, scores of expert panels have been convened to examine the benefits of new practices — urban tree canopies, oyster aquaculture, street sweeping, manure-to-energy technologies and many more.
But the panels in some cases have recommended changes in the amount of nutrient reductions associated with various BMPs. Further, as they interact with new, fine-scale modeling, the effectiveness of BMPs could be increased or decreased in specific places.
Meanwhile, states have been making efforts to identify conservation practices already adopted by farmers — usually those without cost-share funding from conservation agencies — that haven’t been factored into the cleanup effort yet.
On the other hand, the EPA has also been pressing states to clean up their historic BMP data going back to 1985 and removing from their records those that no longer exist, or those that might have been double-counted.
Also, after 2018, the states must begin periodically inspecting BMPs to ensure that they are maintained and functioning. Those not verified will not be counted toward pollution reduction goals.
-- New Models: The Bay Program partnership relies on a series of computer models that have been developed and refined over three decades to estimate the nutrients and sediment reaching the Bay and how they will impact water quality. There is an air quality model, for instance, that estimates atmospheric deposition on the Bay and its watershed; a watershed model that estimates the movement of nutrients from the land to the Bay; and an estuarine model that simulates water quality in the mainstem of the Chesapeake. In addition, there are a variety of sub-models that cover land uses, the effectiveness of best management practices, underwater grass habitats, oyster filter feeding and more.
The models have undergone significant refinements since they were used to establish TMDL goals in 2010. Changes have focused on the better handling of local movements of nutrients in the watershed — especially phosphorus — and local water quality conditions in shallow parts of the Bay.
The refinements should provide a clearer picture of how nutrients move across the landscape; how that movement may vary regionally; and how the Bay’s water quality is ultimately affected. Because the models are calibrated against decades of historical water-quality monitoring data, their updating should not yield major changes in the overall estimates of nutrients reaching the Bay. It may revise tallies of where nutrients are coming from, though it is too early to say by how much.
Another change: Many of the nutrient reduction actions on the landscape take years before they actually affect the amount reaching the Bay. For the first time, the updated watershed model will be able to give an idea of the time lag— and therefore when the Chesapeake might be cleaned up.
-- Monitoring: The Bay Program has long been criticized for being overly reliant on computer models as its primary tool for assessing pollution reduction efforts.
Over the last decade and a half, beefed-up monitoring in tributaries has provided better information about trends in nutrient and sediment pollution and their sources. Those data are expected to give the midpoint assessment a better picture of real-world conditions, and what’s driving those trends. Improved monitoring also could play a bigger role in tracking cleanup progress.
EPA officials are already experimenting, for the first time, with translating nutrient reduction goals — now spelled out in pounds removed from wastewater and runoff per year — into predicted loads of nitrogen and phosphorus in some local waterways. Cleanup efforts could then be tracked with real-world water quality monitoring, rather than by relying on simulations of virtual stream conditions generated by computer models.
-- Land Use: Very little affects nutrient pollution more than land use. For the watershed model, all land in the 64,000-square-mile watershed is given a use, such as impervious surface or pavement, turf grass, pasture, degraded riparian pasture, forest, disturbed forest and so on. Each of these land uses is assigned a different nutrient loading rate by teams of experts based on a variety of factors.
Land use designations in the model have sometimes been highly contentious because in many cases they did not accurately reflect local conditions. For the midpoint assessment, land use information has been overhauled. It’s been revised based on new satellite imagery that provides 1-meter-square detail for the entire watershed, incorporating roads, buildings — even stream forest buffers — that previously went unseen.
In addition, local governments have been invited to provide information on their communities and to review what’s been put together by the Bay Program. So far, local governments representing about 80 percent of the watershed population have provided local land use, land cover, zoning or other information.
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-- Sediment: Agriculture, the largest source of nutrients, is not on the trajectory to meet 2017 goals in most states, though the most significant shortfall is in Pennsylvania. Agricultural nitrogen was reduced from 113.8 million pounds in 2009 to 99.2 million pounds in 2015, but needs to reach 88.7 million pounds in 2017 and 71.9 million in 2025.
Click Here to read the entire article.
For more on Chesapeake Bay-related issues in Pennsylvania, visit the CBF-PA webpage. Click Here to sign up for Pennsylvania updates (bottom of left column).
For more on Chesapeake Bay-related issues in Pennsylvania, visit the CBF-PA webpage. Click Here to sign up for Pennsylvania updates (bottom of left column).
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