National Water Act, 1998 (Act No. 36 of 1998)NoticesReserve Determination of Water Resources for the Catchments of the Olifants-Doorn in terms of section 16(1) and (2)6. Estuary component |
Geographical boundaries of the Olifants Estuary
Downstream boundary: |
Estuary mouth (31o 42.00'S; 18o 11.34'E). |
Upstream boundary: |
Extent of tidal influence, i.e. the causeway at Lutzville - about 36km from the mouth (31o 33.80'S; 18o 19.78'E). |
Lateral boundaries: |
5m contour above Mean Sea Level (MSL) along each bank. |
QUANTIFICATION OF ESTUARINE ECOLOGICAL RESERVE
RECOMMENDED ECOLOGICAL FLOW REQUIREMENT
The Olifants Estuary has been targeted as a Desired Protected Area (DWAF, 2004). According to the guidelines for assigning a recommended REC the estuary, therefore needs to be in a Category A or the Best Attainable State (BAS). However, with large dam developments already existing in the catchment (e.g Clanwilliam Dam) it will be difficult to improve the Olifants Estuary to a Category A. It is therefore recommended that the Olifants Estuary be improved to the minimum REC for a 'Highly Important estuary', namely a Category B. Scenario 2, i.e. the Present inflow scenario plus the Ecological Water Requirement releases of the River (MAR= 800.3 X 106 M3) is selected as the recommended Ecological Flow Requirement Scenario for the Olifants Estuary. The flow distributions are summarised below:
ECOLOGICAL SPECIFICATIONS
Ecological Specifications are clear and measurable specifications of ecological attributes (in the case of estuaries - hydrodynamics, sediment dynamics, water quality and different biotic components) that define a specific ecological reserve category, in the case of the Olifants Estuary for a Category B. Thresholds of potential concern (TPC) are defined as measurable end points related to specific abiotic or biotic indicators that if reached (or when modelling predicts that such points will be reached) prompts management action.
