(a) This section applies only to a municipality:
(1) with a population of less than 3,000;
(2) through which the Blanco River flows; and
(3) that is located in a county that:
(A) is adjacent to the county in which the State Capitol is located; and
(B) has a population of at least 250,000.
(b) Notwithstanding any other provision of this chapter, a municipality to which this section applies may use revenue from the municipal hotel occupancy tax for the promotion and preservation of dark skies through construction and maintenance of infrastructure and the purchase and installation of hardware that reduces light pollution and sky glow.

(c) Notwithstanding any other provision of this chapter, a municipality to which this section applies may use revenue from the municipal hotel occupancy tax for promotional and event expenses for an ecological tourism event, including an event for which the primary attraction is traveling to an area of natural or ecological interest for the purpose of observing and learning about wildlife and the area’s natural environment, if:
(1) a majority of the event’s participants are tourists; and
(2) the event substantially increases economic activity at hotels and motels within or in the vicinity of the municipality.
(d) A municipality that uses revenue from the municipal hotel occupancy tax for a purpose described by Subsection (b) or (c):
(1) shall determine the amount of area hotel revenue attributable to events and activities related to those purposes for five years after the date the municipality first uses hotel occupancy tax revenue for a purpose described by Subsection (b) or (c); and
(2) may not spend municipal hotel occupancy tax revenue for the purposes described by Subsections (b) and (c) in a total amount that exceeds the amount determined under Subdivision (1).
(e) A municipality may not spend more than 25 percent of the municipality’s annual hotel occupancy tax revenue for the purposes described by Subsections (b) and (c).
(f) A municipality to which this section applies may not reduce the amount of revenue that the municipality uses for a purpose described by § 351.101(a)(3) to an amount that is less than the average amount of revenue used by the municipality for that purpose during the 36-month period that precedes the municipality’s use of revenue under Subsection (b) or (c).