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Section 816.44 Continued. <br />(b) When streamflow is allowed to be diverted, the stream channel <br />diversion shall be designed, constructed, and removed, in accordance <br />with the following: <br />(1) The longitudinal profile of the stream, the channel, and the flood- <br />plain shall be designed and constructed to remain stable and to prevent, <br />to the extent possible using the best technology currently available, <br />additional contributions of suspended solids to streamflow or to runoff <br />outside the permit area. These contributions shall not be in excess of <br />requirements of State or Federal law. Erosion control structures such <br />as channel lining structures, retention basins, and artificial channel <br />roughness structures shall be used in diversions only when approved by <br />the regulatory authority as being necessary to control erosion. These <br />structures shall be approved for permanent diversions only where they <br />are stable and will require infrequent maintenance. <br /> (2) The combination of channel, bank, and flood-plain configurations <br /> shall be adequate to pass safely the peak runoff of a 10-year, 24-hour <br /> precipitation event for temporary diversions, 100-year, 24-hour precipi- <br /> tation event for permanent diversions, or larger events specified <br /> by the regulatory authority. However, the capacity of the channel <br /> itself should be at least equal to the capacity of the unmodified stream <br /> channel immediately upstream and downstream of the diversion. <br /> (c) When no longer needed to achieve the purpose for which they were <br /> authorized, all temporary stream channel diversions shall be removed and <br /> the affected land regraded and revegetated, in accordance Sections <br /> 816.24, 816.25, 816.101-816.105, and 816.111-816.117. At the time <br /> diversions are removed, downstream water treatment facilities previously <br /> protected by the diversion shall be modified or removed to prevent over- <br /> topping or failure of the facilities. This requirement shall not re- <br /> lieve the person who conducts the surface mining activities from mainte- <br /> nance of a water treatment facility otherwise required under this Part <br />• or the permit. <br />816-43 <br />