"Sec. 1   RCW 46.61.415 and 1977 ex.s. c 151 s 36 are each amended to read as follows:
     (1) Whenever local authorities in their respective jurisdictions determine on the basis of an engineering and traffic investigation that the maximum speed permitted under RCW 46.61.400 or 46.61.440 is greater or less than is reasonable and safe under the conditions found to exist upon a highway or part of a highway, the local authority may determine and declare a reasonable and safe maximum limit thereon which
     (a) Decreases the limit at intersections; or
     (b) Increases the limit but not to more than sixty miles per hour; or
     (c) Decreases the limit but not to less than twenty miles per hour.
     (2) Local authorities in their respective jurisdictions shall determine by an engineering and traffic investigation the proper maximum speed for all arterial streets and shall declare a reasonable and safe maximum limit thereon which may be greater or less than the maximum speed permitted under RCW 46.61.400(2) but shall not exceed sixty miles per hour.
     (3)(a) Cities and towns in their respective jurisdictions may establish a maximum speed limit of twenty miles per hour on a nonarterial highway, or part of a nonarterial highway, that is within a residence district or business district. A city or town must hold a public hearing on lowering the speed limit and must hold such hearing at a time when the people most impacted by the lower speed limit would be able to attend. A city or town legislative action to lower a speed limit under this section is subject to any applicable referendum procedure in place in the city or town.
     (b) Counties, with a state university extension office located on a state highway within their respective jurisdictions, may decrease the maximum speed limit on the state highway on which the extension office is located. The speed on such state highway may be less than the maximum speed permitted under RCW 46.61.400(2).
     (c) A speed limit established under this subsection by a city, town, or county does not need to be determined on the basis of an engineering and traffic investigation if the city, town, or county has developed procedures regarding establishing a maximum speed limit under this subsection. Any speed limit established under this subsection may be canceled within one year of its establishment, and the previous speed limit reestablished, without an engineering and traffic investigation. This subsection does not otherwise affect the requirement that cities, towns, and counties conduct an engineering and traffic investigation to determine whether to increase speed limits.
     (d) When establishing speed limits under this subsection, cities, towns, and counties shall consult the manual on uniform traffic control devices as adopted by the Washington state department of transportation.
     (e) Any reduction in a speed limit enacted by a local authority on a nonarterial highway or state highway under this subsection may not be targeted by law enforcement for repetitive, overzealous speed enforcement for the sole purpose of generating a higher than average number of citations.
     (4) The secretary of transportation is authorized to establish speed limits on county roads and city and town streets as shall be necessary to conform with any federal requirements which are a prescribed condition for the allocation of federal funds to the state.
     (((4))) (5) Any altered limit established as hereinbefore authorized shall be effective when appropriate signs giving notice thereof are erected. Such maximum speed limit may be declared to be effective at all times or at such times as are indicated upon such signs; and differing limits may be established for different times of day, different types of vehicles, varying weather conditions, and other factors bearing on safe speeds, which shall be effective when posted upon appropriate fixed or variable signs.
     (((5))) (6) Except as provided in subsection (3)(b) of this section, any alteration of maximum limits on state highways within incorporated cities or towns by local authorities shall not be effective until such alteration has been approved by the secretary of transportation."