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. District Court in Pitkin County rejected the same arguments. The applicant contends that the 4 cfs survival flow is adequate and that the studies conducted during the 1990's do not refute this contention, They supply their own consultant's report that they claim supports the theory that the 4 cfs survival flow will not impact the fishery over the period of days that the SWSD may deplete the stream to that level. The Permittee's contentions that we do not have a legal justification to modify the permit are inaccurate. The regulations at 33 CFR 325.7(a) state clearly the reasons and justification for modifying a permit. This action we are considering is in accordance with those regulations. . 7. Evaluation of Technical Reports: The salient point for this petition is whether or not the permit issued to the SWSD will create significant degradation to the aquatic environment in Snowmass Creek, and if that impact violates the legal standards the Corps must abide by, primarily the Section 404 (b )(1) Guidelines, and whether the impact is contrary to the public interest. The arguments concerning the 1978 agreements and our reliance on those agreements in issuing the permit are difficult to understand with certainty. In reading the District Court judge's opinion, all that can be determined in relation to our permit decision is that the Caucus was not represented by counsel when they signed the agreement, as the judge points out, and that they signed a rather tenuous agreement at best. With the exception of the survival flow determination, the SWSD only agreed to assess possible alternatives for water sources and additional storage, and initiate conservation measures. They did evaluate other alternative sources and storage, deciding those alternatives were too expensive. There was nothing binding in the agreement concerning costs of alternatives or criteria allowing for the rejection of an alternative. It is important to note that the Corps of Engineers has not made any determinations regarding the validity of the SWSD's claims that storage alternatives are too expensive. Fortunately, we have a wealth of scientific information on Snowmass Creek; in fact, we may have more technical information on the impacts of minimum flows for this stream than for most other streams of similar size in Colorado. We have several types of information: 1) Hydraulic criteria including both the Instream Flow Incremental Method (IFIM) and R2CROSS reports that use computer models generated from hydraulic data collected at stream cross- sections, 2) habitat evaluations based on habitat preferences of trout, 3) reports on the effects of anchor ice at low flows, and 4) one report that provides empirical data collected on spawning habitat and winter habitat in Snowmass Creek. a) Hydraulic Criteria: The IFIMiPHABSIM models were developed to assess sa1monid fishery habitats in streams. They use data collected from a series of stream cross-sections taken in habitat types in a given reach. The data collected includes velocity profiles, streambed profiles, water surface elevations and discharges. The model generates available trout habitat at different discharges through the use of habitat suitability curves, which represent known habitat requirements for the different life stages of each trout species. The available habitat generated by the model is in square feet of habitat per 1000-foot length of stream, termed Weighted Useable Area (WUA). We have IFIM reports from two authors, W, 1. Miller & Associates, working for Pitkin County (Miller 1992 and Miller 1993) and Chadwick Ecological Consultants, working for the Aspen Skiing Company (Chadwick 1992, Chadwick 1993, and Chadwick 1996). We also have reports from the Colorado Division of Wildlife (CDOW) using their R2CROSS . method while assisting the CWCB on the in-stream flow determinations. The R2CROSS method 5