(1) In-stream structures are those structures placed by humans within a stream or river waterward of the OHWM that either cause or have the potential to cause water impoundment or the diversion, obstruction, or modification of water flow. In-stream structures may include those for hydroelectric generation, irrigation, water supply, flood control, transportation, utility service transmission, structures primarily intended for fisheries management, or other purposes. Docks, piers, and marinas are not regulated as in-stream structures in this section. See PMC 29.20.150, Transportation – Trails, roads, and parking, and PMC 29.20.160, Utilities, for regulations governing road and utility crossings of streams.
(a) The location, planning, and design of in-stream structures shall be compatible with the following:
(i) The full range of public interests; existing agricultural activities; water diversion operations, maintenance, and facility upgrade activities; and providing for public access to shoreline waters, desire for protection from floods, and need for preservation of historic and cultural resources.
(ii) Protection and preservation of ecosystem-wide processes and ecological functions, including, but not limited to, fish and wildlife, with special emphasis on protecting and restoring priority habitats and species and water resources and hydrogeological processes within the context of the hydrology and water management effects of the Columbia and Snake river operations and McNary Pool conditions, as applicable.
(b) New structures shall be designed, located, and constructed consistent with mitigation sequencing principles in PMC 29.15.040, Environmental protection, and as otherwise limited by floodplain regulations found in PMC 29.15.080, Flood hazard reduction, and PMC 29.25.060, Flood hazard areas.
(c) New structures shall be designed and located to minimize removal of riparian vegetation and, if applicable, to return flow to the stream in as short a distance as possible.
(d) In-stream structures shall provide for adequate upstream and downstream migration of resident fish, as applicable, and shall not adversely affect salmonid fish species or adversely modify salmonid fish habitat, as applicable.
(e) Utilities and transmission lines shall be located so as to minimize obstruction or degradation of views and comply with applicable provisions of PMC 29.20.160, Utilities.
(f) Mitigation shall be required of the proponent for the loss of ecological functions and processes pursuant to PMC 29.15.040, Environmental protection, and Chapter 29.25 PMC, Critical Areas. No net loss in function, value, or acreage shall occur from such development.
(3) Submittal Requirements. In addition to the standard requirements listed in PMC 29.35.040, Application requirements, all permit applications for in-stream structures shall contain, at a minimum, the following additional information:
(a) A site suitability analysis, which provides sufficient justification for the proposed site; the analysis must fully address alternative sites for the proposed development.
(b) Proposed location and design of primary and accessory structures, transmission equipment, utility corridors, and access/service roads.
(c) A plan that describes the extent and location of vegetation which is proposed to be removed to accommodate the proposed facility, and any site revegetation plans required by this SMP.
(d) A hydraulic analysis prepared by a licensed professional engineer that sufficiently describes the project’s effects on streamway hydraulics, including potential increases in base flood elevation, changes in stream velocity, and the potential for redirection of the normal flow of the affected stream.
(e) A hydrologic analysis that analyzes the project’s effects on ecological processes, including delivery and rate of water and sediment, geomorphology, and recruitment of organic material.
(f) Biological resource inventory and analysis that sufficiently describes the project’s effects on fish and wildlife resources, prepared by a qualified professional as defined in Chapter 29.25 PMC, Critical Areas.
(g) Provision for erosion control, protection of water quality, and protection of fish and wildlife resources during construction.
(h) Long-term management plans that describe in sufficient detail the provisions for protection of in-stream resources during construction and operation; the plan shall include means for monitoring its success.