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It is envisaged that these data will allow the quinquennial review process to answer<br />

the following questions (Anon, 2005a):<br />

1. Are the Bay and the tributaries progressing toward TMDL targets <strong>as</strong> expected? If<br />

progress is unclear, how should monitoring efforts be modified to detect trends?<br />

If there h<strong>as</strong> not been adequate progress, how might the implementation actions<br />

or allocations be modified?<br />

2. What are the pollutant loads for the various source categories (including naturally<br />

occurring background pathogen contributions and the contribution from open<br />

space lands), how have these loads changed over time, how do they vary<br />

se<strong>as</strong>onally, and how might source control me<strong>as</strong>ures be modified to improve load<br />

reduction?<br />

3. Is there new, reliable, and widely accepted scientific information that suggests<br />

modifications to targets, allocations, or implementation actions? If so, how<br />

should the TMDL be modified?<br />

4. The allocations <strong>as</strong>sume a conservative bacterial die-off rate of 0.02 per hour.<br />

This value is b<strong>as</strong>ed on rates reported for San Francisco Bay in 1970. If bacterial<br />

die-off is found to be higher, higher allocations may be considered. What are<br />

bacterial die-off rates in the water column and stream sediments? Do they vary<br />

by se<strong>as</strong>on? What are bacteria transport times from sources to the Bay?<br />

5. How does estuarine mixing and dilution of tributary waters vary by flow and<br />

se<strong>as</strong>on?<br />

6. What is the relationship between precipitation, run-off, tributary loads, Bay coliform<br />

levels, and water quality exceedances and shellfish harvesting closures?<br />

7. Are there bacteria in Tomales Bay sediments that enter the water column during<br />

storm events? If yes, how should this process be accounted for?<br />

A b<strong>as</strong>eline faecal coliform tributary and Bay water quality monitoring programme<br />

is also planned from January 2006 with weekly sampling intervals for five weeks,<br />

thence monthly, sampling from March to December. Clearly, this programme would<br />

not be adequate to address the questions above and further investigations would be<br />

required to address the detailed scientific issues implied in these questions.<br />

Parallels with WFD<br />

There are many parallels between TMDLs and WFD ‘programmes of me<strong>as</strong>ures’,<br />

both require significant stakeholder engagement, they operate at the catchment or<br />

drainage b<strong>as</strong>in scale and commence by defining the ‘pressures and impacts (WFD)’<br />

or ‘problem statement’ (TMDL).<br />

The existing TMDL studies are clearly ahead of the implementation of WFD<br />

‘programmes of me<strong>as</strong>ures’ in the area of faecal indicator flux modelling and control<br />

but they do not appear to have, at this early stage, to have developed a set of<br />

operational tools to <strong>as</strong>sist UK authorities with implementation of WFD principles at<br />

‘protected are<strong>as</strong>’ where compliance with FIO standards is to be achieved via WFD<br />

implementation.<br />

28

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