California Agriculture

We examined the efficacy of using transparency-tube measurements to estimate turbidity, total suspended solids (TSS) and particulate nitrogen and phosphorus concentrations in several California waterways. Just as lowering a black-and-white disk (Secchi disk) into a lake provides a convenient way to measure its water clarity, a transparency tube offers a practical alternative for measuring water clarity and suspended solids concentrations in California streams and waterways. While transparency relationships with turbidity and TSS are strongest within a given sampling location, these relationships are relatively robust across a wide range of water bodies displaying contrasting conditions. However, transparency-tube measurements appear to have limited value in predicting particulate nutrient concentrations, even at a given sampling site. The low cost, ease of use and excellent repeatability of measurement make the transparency tube a potentially valuable tool for anyone interested in monitoring water quality, including farmers, ranchers, citizen volunteer groups, schools and local governments seeking to get involved in watershed monitoring programs.