ACTION 5: TMDL DEVELOPMENT

ATLANTIS Consulting ltd will be responsible for undertaking this action in collaboration with Frederick University.

This Action aims to develop TMDLs for selected pollutants applicable to the selected pilot river basin. It is initially proposed that TMDLs will be developed for the following pollutants (pathogens, BOD, Nutrients, pesticides and particulate matter). Modifications or additions to the list of pollutants may occur if during the course of the project other pollutants with significant impact are identified. TMDLs will be applicable for the whole river basin and will be based on ensuring that water quality criteria are met at all significant water bodies located within the basin.

TMDLs are designed to provide a scientific and fully quantitative basis for defining maximum acceptable pollutant release rates into receiving water bodies. In principle they represent the amount of pollution the water is capable of assimilating while maintaining its beneficial functions. It thus can provide the basis for designing and implementing policies and measures concerning pollutant source allocations, for example via the effluent permit system. It is noted that in Cyprus, rivers and streams for the most part have non-permanent flows as is the case also in the Kalo Horio catchment. This creates added difficulties in developing TMDLs as water quality impacts become more difficult to model or predict.

Defining TMDLs will be achieved through the implementation of realistic scenarios which will consider existing and forecasted meteorological scenarios and theoretical total pollutant releases. In defining point source pollutant release rates, the results of the PRTR will be utilised. The definition of non-point release rates will be attained with the use of emission factors and will be facilitate through the HSPF model available in the BASINS System (See Action 3).

Various scenarios of Pollutant Source allocations will subsequently be studied for each pollutant. Scenarios will introduce various realistic combinations of pollutant loads released to the system in order to determine the maximum pollutant release rates that the water bodies can receive without causing the exceedances of criteria concentrations at the receiving waters. Total release rates will be allocated to specific sources as identified and introduced in the model during Actions 2 and 3. Additional fictitious sources will be introduced where the development of such sources may be easily predicted from existing development trends or plans. Views and opinions from Competent Authorities on this matter will be collected through the stakeholder consultation process.

It is noted at this stage that allocating pollutants to the various existing and potential future sources can be a serious cause of controversy and disagreement as it can influence decisions regarding the type and locations of pollutant sources that can be granted permits or which will be required to implement costly pollution control technologies. Defining source allocations therefore constitutes a major part of policy making. Source allocations used at this Action are theoretical and contribute solely to defining TMDLs. For the purposes of defining management measures and selecting BMPs, a stakeholder consultation process is proposed which will aim to define key constraints and requirements on water use as well as well as to determine the key development pressures that can have an impact on pollutant release rates. This Task will be undertaken in Action 6.

TMDL building scenarios will include two options of meteorological / hydrological conditions. Each scenario will be represented in terms of daily time series for a one year period and will represent:

  1. An average meteorological year based on data for the last five years prior to the project.
  2. A worst case scenario which will represent the year with the least rainfall recorded over the last 10 years prior to the project. Two independent sets of TMDLs will thus be produced.

It is noted that a third meteorological scenario based on future climate change scenarios from General Circulation models may be applied provided that a consensus between Competent Authorities can be reached regarding which scenario may be realistically applied and considered during the development of Water Quality Management Measures. Results of TMDLs will be reviewed by the Partners and Competent Authorities such that a consensus on suitable TMDLs is reached. The review process foresees the dissemination of results for examination and meetings between all partners.