Determination of Water Quality Indices for Surface Water Sources in Cross River National Park, Cross River State

Protected forest ecosystems such as Cross River National Park provide critical water regulation services, but their surface water quality may be affected by agricultural encroachment, logging, and community activities in surrounding buffer zones. This study determined water quality indices for surface water sources within and adjacent to Cross River National Park in Cross River State, South South Nigeria. Water samples were collected from eight sampling points representing streams within the park interior, streams at the park boundary, and streams downstream of adjacent agricultural communities. Twenty parameters were measured including pH, dissolved oxygen, biochemical oxygen demand, total coliform, total suspended solids, nitrate, phosphate, turbidity, and selected heavy metals. The National Sanitation Foundation Water Quality Index and the Canadian Water Quality Index were calculated for each sampling point. Streams within the park interior showed high-quality scores of 87 to 92 on the NSF-WQI scale. Boundary streams showed moderate quality scores of 64 to 76. Downstream community streams had the lowest scores of 41 to 58, classified as poor to bad quality. Total coliform counts were highest in downstream samples, indicating faecal contamination from agricultural activities. Nitrate and phosphate concentrations increased markedly in downstream samples. Heavy metals were below detection limits in interior park streams but measurable in downstream locations. These results demonstrate the water quality protection function of the national park and the degrading impact of surrounding human activities, informing buffer zone management policy in Cross River State.

Keywords: water quality index, surface water, Cross River National Park, protected forest, Cross River State