根据之前对成品水隐孢子虫的监测研究，以及在检测到的暴发期间和之后进行的测量，确定了隐孢子虫卵囊的作用水平。当成品水中的卵囊浓度在10-30个/100 L以内或以上时，似乎存在暴发的可能性。在该地区及以下的较低范围内，可能会发生疫情，但可能无法检测到。如果单个样本的计数达到或高于该水平，则应快速进行进一步采样，或考虑补充性能数据以支持决策。包括13个参考文献、表格、图表。

From consideration of prior monitoring studies on finished water Cryptosporidium and measurements made during and after detected outbreaks, an action level for Cryptosporidium oocysts is defined. At concentrations within and above 10-30 oocysts/100 L in finished water, the possibility of an outbreak would appear to exist. In the lower range of this region and below, outbreaks may occur but may not be detectable. If a single sample exhibits counts at or above this level, further sampling on an expedited basis or consideration of supplemental performance data to support a decision should be undertaken. Includes 13 references, table, figure.