Many folks believe that the greatest challenge to improving water quality is eliminating hypoxic zones, often termed “dead zones,” which are areas in lakes and oceans of such low oxygen concentration that aquatic life dies. These hypoxic zones are fueled by the presence of excessive amounts of nutrients – mainly phosphorus and nitrogen. The consequences of last year’s hypoxic zone in Lake Erie exemplify the negative impacts excess nutrients can have on these waterbodies and the human and aquatic life that depend on them. Regional partnership programs, states and the U.S. EPA have taken steps to reduce the size of hypoxic zones in the Chesapeake Bay and the Mississippi River Basin. EPA established a total maximum daily load (TMDL), or a pollution budget, for the Chesapeake Bay in 2010 and the Mississippi River Basin states are developing nutrient management strategies to deal with the challenge in the Gulf of Mexico.
There are glimmers of hope beginning to emerge indicating that progress is slowly being made, though they may be fleeting. This year’s predicted smaller than average dead zone in the Chesapeake Bay is attributed, in part, to the significant nutrient reduction by clean water utilities. In fact, publicly owned treatment works (POTWs) reached their 2025 Chesapeake Bay TMDL goal in 2015, ten years ahead of schedule. According to EPA, wastewater dischargers account for 41% of the estimated Bay-wide nitrogen reductions, and 38% of the estimated Bay-wide phosphorus reductions that took place between 2014 and 2015.1 Clean water utilities are investing in nutrient removal to lower the amount of nutrients they discharge into the Bay. From 1985 to 2015, wastewater cut their total nitrogen and phosphorus loading to the Bay by 43% and 59% respectively.2 Since the 2010 Bay TMDL was established, the wastewater sector has cut nitrogen discharge levels from 52 million pounds to 38 million pounds annually which achieves the 38 million pound 2025 Bay TMDL target ten years ahead of schedule.4 Utilities are embracing their vital role in the community. Their desire to restore the Bay and their hard work and investments are making a difference. Scientists expect this year’s hypoxic zone to be smaller than average.
In contrast, agricultural contributions of nitrogen to the Bay have remained the same and phosphorus contributions have increased over the same 30-year span. The Bay TMDL will continue to be implemented but the agricultural community, though it has load reduction allocations under the TMDL, is not held to mandatory reductions under the federal program. Instead, the states are responsible for finding ways to meet the load targets for agriculture. Despite investment in conservation measures over the past several decades, current approaches to addressing agricultural contributions do not appear to be enough to address the nutrient problem.5 So despite the remarkable strides made by the POTW community, many believe that progress will stall without the ability to hold agricultural dischargers accountable.
The Bay’s success thus far derives from the $7 billion in investments made in advanced wastewater treatment that began with the first Chesapeake Bay cleanup agreement signed in 1983.7 Maryland’s Bay Restoration Fund, which was created to help pay for upgrades to wastewater treatment plants to reduce the levels of the nutrients entering the Bay and its tributaries, has provided more than $1.25 billion.9 In Washington, DC, the single largest discharger in the watershed, Blue Plains operated by DC Water, invested $1 billion in treatment upgrades to reduce their nitrogen output.
As we look westward, however, there is disappointing news from the Mississippi River Basin. The 2015 nitrogen levels in the Gulf of Mexico were the highest they have been since monitoring began in 1997.6 The latest water quality measurements are unfortunate on many levels, but are especially troubling considering the $46 billion that has been spent since 1997 to encourage farmers to reduce farm pollution voluntarily. The Hypoxia Task Force, a state-federal partnership convened by the EPA, is working diligently to shrink the size of the Gulf of Mexico’s dead zone. The question is whether there are lessons to be learned from the Chesapeake Bay that can help turn the tide in the Mississippi River Basin. The Bay is benefiting from aggressive action by the public wastewater community, but agricultural discharges have not improved. The Mississippi River Basin’s challenges are compounded by the fact that wastewater utilities are a small part of the program – less than 10% of the contribution of the overall nutrient load to the Gulf of Mexico.
So while clean water utilities’ investments and nutrient reductions in the Chesapeake Bay are something to celebrate, more work is needed in other vulnerable watersheds, including the Mississippi River Basin, and we need to redouble our efforts to ensure that all contributors, including agriculture, are doing their respective part to solve the nutrient problem.
- Images: https://www.epa.gov/sites/production/files/2016-06/documents/wastewater_progress_report_06142016.pdf