APPROACHES to the ALLOCATION OF LOADS in TMDLS

The TMDL program has likely generated as much controversy as any program in EPA's history. To help water quality professionals navigate the TMDL process, the Water Environment Research Foundation funded a project to address some of the technical and policy issues associated with conducting TMDL studies. The project is a collaborative effort among four firms, each focusing on specific issues or elements of the TMDL process that that firm is uniquely qualified to address.As opposed to many other TMDL issues that are technically based, load allocation “is first and foremost a policy decision on how to distribute costs in order to achieve a water quality goal.” (NAS, 2001) Existing federal TMDL rules provide no specific criteria for allocating loads. Existing guidance on the subject describes a wide range of possible methods for determining allocations, but gives no significant direction on how or why to choose any particular allocation method. A review of 176 approved TMDLs, together with interviews of state TMDL staff, revealed a large majority of documents described only the allocation result, and did not document any method or criteria used for determining the allocation. Very few states were found with any specific guidance for allocation criteria or methodologies, and most TMDL allocations are done on a purely case-by-case basis. Furthermore, although the allocation decision is, in theory, a policy decision, such decisions frequently emerged from the technical analysis of trial-and-error model runs, without explicit documentation of policy considerationsThis research describes a range of approaches to load allocation that have been taken by states. Florida has the most specific allocation criteria of the states reviewed. Several states prescribe a process for developing allocations without specifying any particular allocation methodology. Several states also use technical methods that are used to help inform the allocation decision.In spite of policies favoring the use of effluent trading as a way to generate a market-based allocation outcome, this research found that trading has been looked at only sporadically and still has a very limited track record in relation to TMDLs. We outline a range of factors for a TMDL writer to consider in order to maximize the chance that subsequent trading can be done.Finally, a partial compilation of possible allocation criteria is presented together with factors the TDML professional should consider when deciding which criteria to use.