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Chapter Item -by -item guidance small increase in impervious surface and would add only minor amounts of any potential pollutants, it would be sufficient to qualitatively describe the extent of increase and give a general identification of the types of pollutants involved such as fertilizer and herbicides from suburban lawns or pollutants typical of park- ing lot runoff. On the other hand, if significant increase in runoff or significant amounts or kinds of pollutants would result, a more detailed and quantitative assessment would be necessary to adequately characterize the impacts. Similarly, the amount of detail provided about management or treatment methods should befit the significance of the quantities and quality of the runoff. Where it is dear or suspected that the runoff would pose water quality problems if not adequately man- aged or treated, sufficient detail is needed so that reviewers can judge the adequacy of the proposed system. Locations, dimen- sions and design capacities of detention or retention basins should be given if they will be used to manage runoff. The EAW should discuss the conformance of the proposed system with any applicable requirements of the local municipality and any watershed district with jurisdiction over the area. If the project is subject to a stormwater pollution prevention plan, it should be discussed. • b. The first part of this answer should identify the point(s) of discharge of the stormwater system into receiving waters and also indicate any downstream receiving waters that may be influenced by the stormwater discharge, in terms of volumes or quality. This should include any downstream waters that may be noticeably influenced by the discharge, especially those more sensitive or more valuable than the waters receiving the direct discharge. An estimate of the stormwater impact on the quality of receiving waters should be made. The level of sophistication of this analysis must be guided by the likely magnitude of the impact and the importance of the water body(ies) affected. Where it is clear that only a minor degradation of water quality and no noticeable impairment of water use would result, only a general qualitative discussion is needed. Where noticeable impairment may occur, however, more quantitative assessment methods should be em- ployed, and predictions should be made about whether any water quality standards will be violated. A stormwater discharge that may affect a lake is an example of a situation in which the RGU must exercise judgement about the extent of analysis needed. Generally regarded as sensitive and valued resources, the lake may require a numerical nutrient bud- get analysis to adequately characterize the extent of the potential impact. Any nutrient budget analysis performed should be based on a generally accepted model of a lake's response to increase in phosphorus loading or other critical nutrients if phosphorus is not limiting. The choice of a model should be based on available data, and its expected accuracy based on the likely magnitude of the impact, in addition to the time and costs of using the model. In other words, the greater the likely impact, the greater the need for a more sophisticated model. If insufficient data is available to allow the use of any numerical model, it is necessary to gather the minimally needed data unless the EAW can establish through other analysis that there is no reason to expect noticeable degra- dation. If the matter is left in doubt in the EAW, it may result in calls for an EIS and a more in -depth analysis. 18. Water quality: wastewaters • a. For any project that generates wastewater, details of the sources, composition and amounts need to be given in the EAW. For normal domestic sewage generation such as toilet wastes or wash water from human occupancy, only the amounts need be given, calculated from the number of occupants at a rate of 100 gallons per person per day unless another figure is justified in the particular case. For industrial processes, the sources of all wastewater streams should be identified and a description should be given of how the various potential pollutants enter the stream or are generated within the stream. The anticipated chemical analysis of the vari- ous waste streams should be estimated, and the basis for the estimate should be indicated, such as measurements made at an existing similar plant. • b. Provide sufficient information about the nature of any pro- posed wastewater treatment system to demonstrate that it will be adequate to treat the wastewaters generated. The level of detail needed will depend on the nature of the wastewaters and the proposed system and the degree of treatment that must be achieved; where wastewaters or proposed treatment methods are non - routine, a higher level of detail demonstrating that the sys- tem will work will be necessary. For industrial wastewaters, it is advisable to consult with PCA early in the EAW preparation pro- cess. The second part of this question calls for identification of receiv- ing waters for discharges. This should include any downstream waters that may be noticeably influenced by the discharge, espe- cially those more sensitive or more valuable than the waters receiving the direct discharge. An estimate of the impact of the discharge(s) on the quality of the receiving waters should be made. The level of sophistication of this analysis must be guided by the likely magnitude of the impact and the importance of the water body(ies) affected. Where it is clear on the basis of the amounts and quality of the discharge compared to the volume, quality and assimilative capacity of the receiving waters that only a minor degradation of water quality will occur, and no noticeable impairment of uses of the water would result, only a qualitative discussion is generally needed. Where noticeable impairment may occur, however, more quantitative assessment methods should be employed, and predictions should be made about whether any water quality standards will be violated. 10 EAW Guidelines