River Pollution Mapping Software

Dear Friends, We have collected data from a river and we are trying to map the findings and calculate the level of pollution for the river. We collected and analysed water samples from fixed small interval (20km) for the river. Now we have data like BOD, COD, DO, water Colouration, heavy metals and some other physical properties. Can someone suggest model to map the river pollution and also to evaluate the level of pollution using the data we have?