In
2001, I chaired the National Academy of Sciences review of the USEPA TMDL
program (Assessing the TMDL Approach to Water Quality Management, NRC 2001). At
that time, I was an enthusiastic supporter of TMDLs based on watershed analysis
and improvement of surface water quality based on pollutant load reduction. Two
issues have caused me to reconsider my perspective:
·
My colleagues’
endorsement of in-lake management strategies, such as artificial aeration and
biomanipulation
·
My view that current
water quality criteria may not be good indicators of designated use, resulting
in unnecessary and exorbitant costs of compliance
In the past few years my
colleagues, Dick Osgood and Ken Wagner, have made a compelling case for the ineffectiveness
of watershed pollutant load reductions to achieve compliance with surface water
quality standards in many water bodies; instead they have proposed that in-lake
treatment is often a better management alternative. Their examples are hard to
argue against. So what does this mean for the TMDL Program? Should we
acknowledge the limitations of watershed pollutant load reduction and embrace
in-waterbody treatment processes?
The 1972 Clean Water Act (CWA) was
monumental in its positive effect on our Nation’s water quality. At the same
time, the environmental euphoria of the CWA has sometimes resulted in well-meaning
but non-attainable water quality standards in a number of situations. The
result, in the Chesapeake Bay and in my home state of North Carolina, is water
quality criteria that are not really reflective of underlying designated use.
This is an important point because designated use (e.g., swimmable,
recreational fishery) is what we protect with our water quality standards;
water quality criteria, such as chlorophyll a and dissolved oxygen, are just easily-measurable
(and inexact) surrogates for designated use.
I believe that many surface
water quality criteria that have been established by the States are not adequately
representative of designated use. Further, I believe that in many situations we
have set water quality criteria that have resulted in TMDLs that have associated
costs of compliance that are way beyond expected water quality benefits. At the
same time, I am not a proponent of in-lake treatment processes as an
alternative to watershed pollutant load reduction except in small waterbodies
where studies have demonstrated the effectiveness of in-lake techniques. My
bottom-line perspective on the two issues that I raise – we should revisit the
TMDL program and the underlying surface water quality standards, yet we should not
be taken in by the low-cost, but ineffective in-lake treatment technologies (as
recently employed in North Carolina at a waste of $2 million) unless there is compelling
scientific evidence of their effectiveness.
TMDL approach, of course has its fallacy in theory and implementation, in view of setting use-specific WQ parameters. Cost is obviously another criterion against it. But in-lake treatment in larger watersheds has its limitations but still can be resorted to particularly free from mercury and lead load deficient watersheds. TMDL implementation vis-a-vis new 303 d demands greater vigil and user intervention. I think it requires a revisit of parameters and treatment technologies. I am not sure how North Carolina TMDL program is a waste and would like more light on it by Mr. Ken.
ReplyDeleteKen, Please forgive me for my ignorance and questions.
ReplyDelete1. Are you saying demonstrated preventive storm-water management systems should be implemented concerning effective reduction of TMDL loads and not in-lake treatment? I am not sure I understand what in-lake treatment is but I would like to learn more please. In my laymen terms are you saying we are better off reducing pollution at the source and not managing pollution at the water intake treatment plant? Thanks
In small lakes and ponds, in-lake treatment (e.g., aeration) may work, but it will not be effective in large lakes unless the problems are localized. Watershed pollutant load reductions (TMDLs) can be effective; my concern about TMDLs is that they may be based on water quality criteria that are poor indicators of designated use. I'm not really saying anything about a (drinking) water treatment plant.
DeleteMy strongest reason for disliking the TMDL program is it either based upon, or it seems to always lead regulators to act as if, "bad chemistry" is the reason water resources are limited. The resulting policy is that if we crank down on chemistry or divvy up the pie better everything will work out.
ReplyDeleteThe reality is that habitat alteration is the primary driver in most all situations in Illinois. So are misallocating billions in resources, including thousands of hours of very earnest effort by activists, regulators, and dischargers advocating for various results in permit discussions. This is essentially a diversion from the real problem which is bad habitat, and that is not getting better by being ignored.
Ohio is similar to Illinois in that habitat issues are clearly among the most limiting to attainment of designated uses in streams and rivers. Water chemistry parameters contribute (e.g., nutrients such as TP and nitrate), however the role that instream habitat and floodprone areas contribute to nutrients is under-appreciated. The result is that the toxic algae and nutrient conditions in downstream depositional waters (Lake Erie, Gulf, Grand Lake St Marys) are treated as upland applications problems with lipservice to the influence of floodplains and habitat. The result is that proposed "solutions" focus almost entirely on upland application and management. What we need to do is to re-engineer drainage systems, perhaps with the addition of biofuel crops in lowered floodplains, to remove nutrients in headwater areas before they reach the streams. Biofuel crops may make it economically more feasible and, for phosphorus, work to take it out of the system. In any the case the politically expedient "upland" solutions may not be sufficient to alter the export of nutrient to these waters. There have been efforts to excise aquatic life use protections for small headwater streams (< 3 sq mi) in Ohio with TMDLs focused only on downstream of such reaches. This to avoid the "inconvenient truth" that the ability to remove or keep nutrients out of streams is most effective in very small headwater streams. It is example of too much of a focus on chemistry alone to the detriment of designated uses partly drive by the pressure to develop acceptable TMDLs.
ReplyDelete