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In addition to historic districts and individual historic landmarks, there are additional zoning overlays that the Office of Historic Preservation has review authority over including the River Improvement Overlays (RIO) districts and viewshed districts. These zoning layers are authorized by the City's Unified Development Code and place standards for urban design and development.

River Improvement Overlay (RIO) Districts


RIO is a zoning overlay. Its purpose is to establish regulations to protect, preserve and enhance the San Antonio River and its improvements by establishing design standards and guidelines for properties located near the river. The San Antonio River is a unique and precious natural, cultural and historic resource that provides a physical connection through San Antonio by linking a variety of neighborhoods, cultural sites, public parks and destinations. The districts cover a total of six geographic areas spanning the river from its northern boundary, near Hildebrand Avenue, to a southern boundary near Mission Espada and the southern City Limits. The RIO design objectives were developed through an intensive public input process and were adopted as part of the enabling ordinance approved by City Council on February 21, 2002.

RIO Guidelines

In reviewing an application for a certificate of appropriateness for properties in the six (6) River Improvement Overlay districts, the HDRC and the Office of Historic Preservation (OHP) consider the character and design objectives for each river improvement overlay district, as well as the design standards set forth in the UDC. There are also specific design standards for the Riverwalk specified in the UDC. For additional information, please refer to section 35-670 of the City of San Antonio's Unified Development Code (UDC) and the recent amendments at the link above or contact OHP staff for assistance.


Extending from Hildebrand Avenue south to US Highway 281 North, the northernmost of the six (6) RIO districts includes a mix of residential, commercial, and recreational uses.

The design objectives for RIO-1 are: to maintain the character of existing residential neighborhoods and redevelop commercial nodes; to encourage mixed use redevelopment of the urban character along Broadway and Avenue B; and to maintain scenic open space and the natural character of the river, particularly through Brackenridge Park.

RIO-1 Map


Extending south from US Highway 281 North to Lexington in the northern portion of downtown San Antonio, the area encompassed by RIO-2 includes small single-family residential pockets surrounded by a variety of higher-density and commercial uses.

The design objectives for RIO-2 are: to encourage high-density, mixed-use developments as extensions of the downtown core; to encourage neighborhood and cultural tourism oriented uses as well as those that provide additional housing for downtown workers; to enhance the pedestrian experience with high quality streetscape designs and links to the public Riverwalk; and to enhance the pedestrian experience with high-quality building designs that include balconies facing the river and primary entrances facing the street.

RIO-2 Map


Extending from Lexington south to West Durango Boulevard, RIO-3 includes the traditional Riverwalk "horseshoe" that still maintains many of the original features designed by architect Robert H. H. Hugman.

The design objectives for RIO-3 are: the historic work of Robert Hugman, CCC and WPA construction work, Ethel Harris tile work, and work of the National Youth Administration shall be respected and preserved in all construction efforts, and adherence to the intent and spirit of those plans is essential in all construction; traditional, formal street level design precedents shall be respected, but at the river level, the more informal, handcrafted style shall be maintained; the integrity of historic properties shall be preserved, and historic differences between street level designs and river level designs shall be respected; the traditional design context of the area shall be respected at two levels: the broader downtown context and the immediate block as it faces the river; the microclimate of the river walk level shall be maintained and, during construction, shall be given extra protection, and River operations staff will be consulted to provide specific instructions for construction procedures.

RIO-3 Map


Extending from West Durango Boulevard south to Mission Road, RIO-4 meanders along the Arsenal, through the King William Historic District, and south through a portion of the Mission Historic District.

The design objectives for RIO-4 are: to encourage urban quality mixed-use developments; to preserve and enhance the historic character as well as emphasize the street scene; to construct new development that complements the nearby historic King William area but does not mimic its style; and to encourage new development in clustered nodes.

RIO-4 Map


Extending from Mission Road south to Southeast Military Drive, RIO-5 skirts the San Jose Mission complex.

The RIO-5 design objectives are: to maintain the residential character of the area while encouraging development of new mixed-use nodes that offer neighborhood shopping and services; and to respect established neighborhoods in new top-of-bank riverscape designs, particularly recreational opportunities that require parking or transport of recreational equipment.

RIO-5 Map


Extending from Southeast Military Drive south beyond Southeast Loop 410 that includes the Mission Espada complex, RIO-6 has a distinctly rural character, consisting of rolling riparian prairie.

The design objectives for RIO-6 are: to maintain the historic rural Texas character while encouraging development of new and mixed-use nodes; and to maintain the natural quality at the top of the riverbank using native plants and minimizing formally landscaped areas to preserve the natural character of the river.

RIO-6 Map

RIO-7 DISTRICT for San Pedro Creek

In 2016, City Council adopted UDC amendments which established a new overlay district specific to San Pedro Creek (RIO-7). The overlay places requirements for design review which will ensure quality public and private development within the vicinity of the San Pedro Creek Public Improvements Project.


Map of currently-proposed boundaries (PDF)

The proposed RIO-7 zoning overlay received unanimous approval from the City's Zoning Commission on December 20, 2016. The zoning case will receive final consideration from City Council on January 19, 2017.

The RIO-7 overlay only affects new construction projects and does not require changes to existing buildings or uses that are currently permitted. Properties zoned for single-family residential use are exempt from the RIO-7 overlay.

For more information, please contact us at 210-207-1496 or info@sapreservation.com.

Rendering of San Pedro Creek Improvements, Courtesy of San Antonio River Authority.


The purpose of a Viewshed Protection district is to establish regulations to protect, preserve, and enhance views and vistas. The City of San Antonio has many views and vistas of historic places, landmark buildings, and other sites of cultural importance which have always been important to the city. These views will continue to be amenities and assets of great value to the city, its people, and its economy. Viewshed Protection districts are overlay districts that will be used primarily for unique situations regarding views and vistas that are not adequately covered by the standard zoning districts. No part of a new structure, sign, tower, roof top equipment, or other appurtenance shall be permitted to encroach into any designated viewshed as set forth in this ordinance unless an encroachment was approved legally before the effective date of the Viewshed Protection ordinance. If the maximum height allowed in any zoning district within the city differs from the height permitted by a protection district, the more restrictive height limitation shall apply.

Alamo Viewshed

San Antonio currently has one (1) Viewshed Protection district: Alamo Viewshed (VP-1). This Viewshed Protection district lies behind the main entrance to the front door of the Mission San Antonio de Valero (The Alamo), a local Exceptional Landmark and a National Historic Landmark. A brass disc monument named VP-1, Alamo Viewshed, has been set to mark the viewpoint origination in Alamo Plaza in front of the Alamo Chapel.

The area above a plane described by the following boundary is designated as the Alamo Viewshed Protection District (VP-1): beginning at a point at elevation 663.22 feet above disk VP-1, Alamo Viewshed, and extending through a point of the plane of the façade that is level with and six inches northwest from the topmost northern corner of the Alamo façade at a vertical angle of 9°34’38" and at a distance of 109.23 feet to the east right of way line of Interstate Highway 37 for the northern boundary of the viewshed (see Ch. 35-337 of the Unified Development Code for full boundary description). The images below display the geometry of VP-1.


Mission Protection Overlay Districts (MPOD)

Similar to a Viewshed Protection District, the Mission Protection Overlay Districts were developed specifically for the four southern missions in consideration of the pending World Heritage Status for the sites. In order to protect these important community treasures, the City of San Antonio Office of Historic Preservation developed the MPODs through public feedback. The MPODs regulate building height within a 1,500-foot buffer area of Mission Concepcion, Mission San Jose, Mission San Juan, and Mission Espada.