Analysis of Irrigation Water Quality in Rice Fields in North Tanoyan Village, Lolayan District, Bolaang Mongondow Regency

Analisis Kualitas Air Irigasi Areal Persawahan Desa Tanoyan Utara Kecamatan Lolayan Kabupaten Bolaang Mongondow

Abstract

Irrigation water quality plays a vital role in supporting paddy productivity in North Tanoyan Village, Bolaang Mongondow Regency, an area situated near artisanal gold mining sites. This study aimed to analyze irrigation water quality based on Government Regulation Number 22 of 2021 (Appendix VI, Classes III and IV) and to evaluate the Sodium Adsorption Ratio (SAR) according to Ayers and Westcot (1985). Composite samples were collected from three points along tertiary irrigation canals using a purposive sampling technique. The parameters tested included temperature, TSS, pH, cyanide, mercury, and Na, Ca, and Mg ions. Test results indicated that temperature (30–30.1°C), TSS (2.6–7.1 mg/L), pH (6), and mercury concentrations (0.0002–0.0003 mg/L) remained within national water quality standards for Classes III and IV. However, cyanide levels were detected at 0.0298–0.0318 mg/L, exceeding the Class III threshold (0.02 mg/L). Meanwhile, SAR values ​​were recorded at < 10 (0.48–0.55 mEq/L), classifying the irrigation water as "excellent." These findings indicate cyanide contamination resulting from nearby gold processing activities, which poses a potential threat to the paddy field ecosystem.

Keywords: irrigation, North Tanoyan Village, paddy fields, water quality