High levels of nutrients and sediment have been plaguing the Chesapeake Bay for several years, leading to many problems. Some measures have been taken and efforts have been made to try to lower pollutant loadings to the Bay, but they have not been very successful and these efforts were partially cancelled by the population boom and a rapid development in the Bay. The Total Maximum Daily Load (TMDL) for the Chesapeake Bay and its tributaries was finalized by the USA EPA on December 29, 2010 and came out in April 2011 with the aim of ambitiously reducing nutrients, sediment and total suspended solids (TSS) entering the waterways. The TMDL is seen as a positive step to improve the condition of the Bay.
The reduction will be achieved in different steps:
- Point and non point sources will reduce pollutant loadings in the next several years
- Implementation measures will be instituted by 2025
- A series of intermediate deadlines to ensure continual progress in the implementation of the TMDL in the next 15 years will be imposed. The ‘’milestones’’, for example, are part of these deadlines. Jurisdictions will start the milestones in 2012.
The TMDL sets also ambitious goals for WWTPs within the Bay’s watershed. Many wonder how the TMDL can impose pollution reductions from non point sources that are not addressed by existing regulatory programs related to clean water. Aggressive efforts have already been made over the years to reduce nutrient discharges from WWTPs and it led to significant decreases in pollutant loadings from non point sources and agriculture. The TMDL requires even better results. Large WWTPs are required to decrease discharges of nitrogen by 27% and phosphorus by 26% from 2009 levels. Agriculture must cut its loadings of nitrogen by 38% and phosphorus by 31%.
HISTORY AND CONSEQUENCES
Over the years, different agreements have been reached to reduce pollutant loads and this effort provided good results. However, it has not been enough because of the presence of nutrients and sediment, water quality and water clarity have consequently decreased since the 1970s. Excessive algal growth and low concentrations of dissolved oxygens are part of the chronic problems of the Bay as well.
MAJOR CUTS EXPECTED BY THE TMDL
- Total nitrogen : a reduction of 25 % compared to the 2009 level
- Total phosphorus : 24% less than in 2009
- TSS : a decrease of 20% compared to 2009
The pollution limits are designed to ensure compliance with state water quality standards.
PROCESS TO ELABORATE THE TMDL
The six states within the Chesapeake Bay watershed: Delaware, Maryland, New York, Pennsylvania, Virginia and West Virginia, and the District of Columbia, worked together to help develop the TMDL. They prepared a Phase I Watershed Implementation Plan (WIP), which gives the outlines to each jurisdiction to meet its allocated pollutant loads. Then, each jurisdiction has until early 2012 to develop its Phase 2 WIPs. The WIPs will include additional detail about nitrogen, phosphorus, and sediment controls at the local level.
The role of EPA is to ensure pollution reductions and to ensure that the jurisdictions enforce the measures. If a plan is inadequate or the progress is insufficient, the EPA may take the appropriate contingency actions and require additional reductions pollution reductions from non point sources such as WWTP. Point sources have achieved enormous reductions of nutrients in the bay, but it would be too expensive and unproductive to rely ultimately on further reductions from WWTPs.
The TMDL is a promising step in the field of pollutants reductions. However, issues like funding, legal and legislative challenges could delay or affect its implementation.
If you have any questions about pollutants, non point sources or WWTPs, please contact John McAllister at firstname.lastname@example.org or at (508) 747 - 7900 x 117.
Information in this article taken from April 2011, article ‘Chesapeake Bay TMDL calls for steep cuts in nutrient, sediment loads‘’ by Jay Landers, published in WE&T.