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Mr. Michael Jewell 12 waterways outside the project area that are part of critical habitat. These effects would be considered offset by the purchase of 120 credits at a delta smelt conservation bank. To: Implementation of the proposed project will affect PCE ##1 Physical Habitat as described under —the-environmental-baselin&-section-above—Construction-of-the- gat"tructures will -result -in the -- permanent loss of shallow water habitat of about 1.52 acre and temporarily affect 3 acres. These effects will be offset through the purchase of 4.56 credits at a delta smelt conservation bank. Operation of the gate structures will result in partial effects primarily on 238 acres of habitat east of the closure structures (Effects of the Action - Delta Smelt). There would also be some increment of effect of gate structure operation on tidal functions and values in connected waterways outside the project area that are part of critical habitat. These effects would be considered offset by the purchase of 26.56 credits at a delta smelt conservation bank. 11. CHANGE the following in Amount or Extent of Take, Delta Smelt, on p. 31, as follows: From: The Service expects that incidental take of delta smelt will be difficult to detect or quantify for the following reasons: the small size of adults and larvae, the difficulty of detecting delta smelt in their turbid aquatic habitat, and the low likelihood of finding dead or impaired specimens. The Service anticipates that the extent of incidental take will be minimized due to the proposed conservation measures and low relative abundance. Due to the difficulty in quantifying the number of delta smelt that will be taken as a result of the proposed action, the number of acres of affected habitat becomes a surrogate for the species that will be taken. The Service anticipates that all individual adult delta smelt in 4 acres of the action area may be subject to incidental take in the form of harm as described in this biological opinion (1 acre of fill in the footprints of the closure structures; 3 acres of temporary lass in the construction area of the closure structures). As for the effect of tidal gate operations on the 233 acres of SWH east of the closure structures that would be seasonally and diurnally affected by gate operation, incidental take of delta smelt will be difficult to evaluate directly. Because of the extremely low population of the species, sampling is unlikely to detect smelt even if they were present. Any such detections will mean that take is occurring and our analysis requires re-evaluation. Initially, the Corps will develop and conduct a fixed term of focused pre- and post -project sampling within the affected sloughs required as a term and condition of this biological opinion. We acknowledge that the effects are partial, and would be offset by purchase of credits. We anticipate incidental take of two (2) adult or juvenile delta smelt for the area affected by the closure structures. Detection of two adult or juvenile delta smelt in Smith Canal or Fourteenmile Slough during the focused sampling by the Corps, or within these waters by other independent sampling after the project has been completed, will mean that the smelt is being or could be affected by the project in excess of the expected effects in these locations.