From 2010 through the end of 2016, the Bay region had achieved only half of the nitrogen reductions it was to have accomplished by the end of this year, according to new figures from the state-federal Bay Program partnership.

Only three of the Bay watershed’s seven jurisdictions were on pace to achieve their 2017 pollution goals for the key nutrient, the data show. In several cases, states were only slightly off track, but for others, especially Pennsylvania and New York, the gaps remain large.

The numbers, stemming from annual reports from the states, were better for phosphorus, where all jurisdictions except New York were on pace to meet 2017 goals. The region as a whole is on track to meet the end-of-year goal for that nutrient.

The figures released in late June are estimates based on computer modeling looking at how actions taken by states from 2010 through 2016 should affect the amount of water-fouling nutrients reaching the Chesapeake.

A cleanup plan approved by the U.S. Environmental Protection Agency in 2010 requires the six states in the Bay watershed and the District of Columbia to reduce the amount of those pollutants to levels that would end the Chesapeake’s chronic oxygen-starved summertime dead zones, dramatically expand underwater grass beds and reduce algae blooms. The improved conditions are intended to help fish, shellfish and waterfowl thrive.

States are supposed to have enough practices in place by the end of 2017 to achieve 60 percent of the required reductions, with all needed actions implemented by 2025. But through the end of last year, practices were in place to achieve only about 30 percent of the ultimate nitrogen goal.

While the picture is better for phosphorus, it is likely to change — potentially significantly — when the Bay Program switches to a new computer model later this year to estimate nutrient control effectiveness.

The new model reflects a wealth of new scientific knowledge, including research showing that agricultural soils in many parts of the watershed have become so saturated with phosphorus that they are leaking more than previously thought.

For nitrogen, the data show that only Virginia, West Virginia and the District of Columbia were on pace to meet their 2017 goals. The shortfalls were greatest in New York and especially Pennsylvania — the largest nitrogen contributor — which has been struggling to “reboot” its lagging efforts to control runoff from agriculture and stormwater.

Across the watershed, about three-fourths of all the nitrogen reductions since 2010 have come from wastewater treatment plant upgrades, which are ahead of schedule in all states except New York.

Overall, wastewater plants have already achieved their 2017 goals, and have nearly reached their 2025 objective. That means most future reductions will have to come from agriculture and stormwater sources, where control efforts have proven to be more difficult. Indeed, nitrogen from stormwater is actually increasing.

The Chesapeake Bay Foundation, which did its own analysis of cleanup progress for Maryland, Virginia and Pennsylvania, commended state actions for contributing to improved water quality in the Bay in recent years, but warned that they need to ramp up efforts to rein in pollution from farms and urban areas alike.

“The success all three states have had in reducing pollution from sewage treatment plants is important, but it also masks shortfalls in each of the states’ efforts to reduce pollution from agriculture and urban/suburban runoff,” said CBF President Will Baker. “Continued federal and state investments will be key to success on the state level, and we know the payoff will be significant.”

The EPA’s annual evaluation of state efforts was not available when the Bay Journal went to press.