Biofouling control in ground-water systems depends upon early detection as part of a maintenance program. However, standard methods of analysis for biofouling components have not provided reliable detection in operational use. Improved methods have been useful in evaluating and predicting biofouling in ground water systems. Filtration and flowcell methods improve sample quality collection, enhancing the usefulness of microscopy. Time-series sampling improves the usefulness of culture analysis of biofouling waters. Prepackaged cultural methods provide practical on-site culture analysis. Used together, such methods provide early warning of biofouling, permitting timely judgments on relative severity, type, and location of the problem. These improvements in methods are being incorporated into standard practices. Although fully quantitative methods of assessing biofouling are not currently available, present methods can be useful to monitor ground water systems for operational purposes. Method development is at the point where a standard guide for biofouling monitoring in operational practice is possible.