Wastewaters derived from the use of geothermals occurring in Ayaş county (Ankara) where these are later discharged to İlhan stream, which is used for irrigation. Pollution potential of the geothermal wastewaters on local agricultural products and pollution with impact on the water quality of the stream after the discharge was the main subject of this project.

Analyses carried out on the water samples representing geothermal waters, streamwaters, geothermal discharge waters, ground waters and drinking waters were assessed according to the threshold values stated by Technical Principles Statement of Water Pollution Control Regulation and to various international standards. Analyses data of wheat, tomatoes, sugar beet, carrot, and clover samples were evaluated with respect to the bioconcentration index values.

In the water samples collected in two phases, before and after the irrigation season, heavy metal and trace elements including arsenic (As); 26.93-234.57 μg L^-1, molibdenum (Mo); 17.3-67.4 μg L^-1, boron (B); 2.58-8.74 mg l^-1 were measured along with water quality parameters including Ec; 3120- 7970 μS cm^-1, pH; 8.6-9.3, chloride (Cl); 40.64-1140.47 mg l^-1, sulfate (SO4); 675.34-5622.91 mg L^-1 and total salt concentration 1210.24-5676,8 mg l^-1. For the samples taken from various parts of the plants, bioconcentration index values revealing pollution potential with respect to the macro-micro nutrition elements with heavy metal and trace elements were calculated. As a result of evaluations of the subject area waters, these are classified as V. Class (unsafe) water quality and it is concluded that their usability rate as irrigation water is 33.3%.