§ 30-5-92. CRITICAL WATER QUALITY ZONES ESTABLISHED.

(A)

In the water supply rural watersheds, water supply suburban watersheds, and Barton Springs zone, a critical water quality zone is established along each waterway classified under Section 30-5-91 ( Waterway Classifications ).

(1)

The boundaries of a critical water quality zone coincide with the boundaries of the 100 year flood plain calculated under fully developed conditions as prescribed by the Drainage Criteria Manual, except:

(a)

for a minor waterway, the boundaries of the critical water quality zone are located not less than 50 feet and not more than 100 feet from the centerline of the waterway;

(b)

for an intermediate waterway, the boundaries of the critical water quality zone are located not less than 100 feet and not more than 200 feet from the centerline of the waterway;

(c)

for a major waterway, the boundaries of the critical water quality zone are located not less than 200 feet and not more than 400 feet from the centerline of the waterway; and

(d)

for the main channel of Barton Creek, the boundaries of the critical water quality zone are located 400 feet from the centerline of the creek.

(2)

Notwithstanding the provisions of Subsections (A)(1)(a), (b), and (c), a critical water quality zone does not apply to a previously modified drainage feature serving a railroad or public roadway right-of-way that does not possess any natural and traditional character and cannot reasonably be restored to a natural condition, as prescribed in the Environmental Criteria Manual.

(B)

In the suburban watersheds, a critical water quality zone is established along each waterway classified under Section 30-5-91 ( Waterway Classifications ).

(1)

for a minor waterway, the boundaries of the critical water quality zone are located 100 feet from the centerline of the waterway;

(2)

for an intermediate waterway, the boundaries of the critical water quality zone are located 200 feet from the centerline of the waterway;

(3)

for a major waterway, the boundaries of the critical water quality zone are located 300 feet from the centerline of the waterway;

(4)

the critical water quality zone boundaries may be reduced to not less than 50 feet from the centerline of a minor waterway, 100 feet from the centerline of an intermediate waterway, and 150 feet from the centerline of a major waterway if the overall surface area of the critical water quality zone is the same or greater than the surface area that would be provided without the reduction, as prescribed in the Environmental Criteria Manual; and

(5)

notwithstanding the provisions of Subsections (B)(1), (2), and (3), a critical water quality zone does not apply to a previously modified drainage feature serving a railroad or public roadway right-of-way that does not possess any natural and traditional character and cannot reasonably be restored to a natural condition.

(C)

In an urban watershed, a critical water quality zone is established along each waterway with a drainage area of at least 64 acres. This does not apply in the area bounded by IH-35, Riverside Drive, Barton Springs Road, Lamar Boulevard, and 15th Street.

(1)

The boundaries of the critical water quality zone coincide with the boundaries of the 100-year floodplain calculated under fully developed conditions as prescribed by the Drainage Criteria Manual; provided that the boundary is not less than 50 feet and not more than 400 feet from the centerline of the waterway.

(2)

Notwithstanding the provisions of Subsection (C)(1), a critical water quality zone does not apply to a previously modified drainage feature serving a railroad or public roadway right-of-way that does not possess any natural and traditional character and cannot reasonably be restored to a natural condition.

(D)

Critical water quality zones are established to include the inundated areas that constitute Lake Walter E. Long, Lake Austin, Lady Bird Lake, and the Colorado River downstream of Lady Bird Lake.

(E)

Critical water quality zones are established along and parallel to the shorelines of Lake Travis, Lake Austin, Lady Bird Lake, and Lake Walter E. Long.

(1)

The shoreline boundary of a critical water quality zone:

(a)

for Lake Travis, coincides with the 681.0 foot contour line;

(b)

for Lake Austin, coincides with the 492.8 foot contour line;

(c)

for Lady Bird Lake, coincides with the 429.0 foot contour line; and

(d)

for Lake Walter E. Long, coincides with the 554.5 foot contour line.

(2)

The width of a critical water quality zone, measured horizontally inland, is:

(a)

100 feet; or

(b)

for a detached single-family residential use, 75 feet.

(F)

Critical water quality zones are established along and parallel to the shorelines of the Colorado River downstream of Lady Bird Lake.

(1)

The shoreline boundary of a critical water quality zone coincides with the river's ordinary high water mark, as defined by Code of Federal Regulations Title 33, Section 328.3 ( Definitions ).

(2)

The inland boundary of a critical water quality zone coincides with the boundary of the 100-year floodplain as delineated by the Federal Emergency Management Agency, except that the width of the critical water quality zone, measured horizontally inland, is not less than 200 feet and not more than 400 feet.

Source: City Code Section 25-8-92; Ord. 031211-11; Ord. 031211-42; Ord. 20080228-116; Ord. 20131017-046; Ord. No. 20170615-102 , Pt. 41, 6-15-17.