Mansfield Dam

{{Short description|Dam on the Colorado River near Austin, Texas, United States}}

{{Use mdy dates|date=April 2025}}

{{Use American English|date=January 2025}}

{{Infobox dam

| name = Mansfield Dam

| image = MansfieldDam2018.jpg

| image_size = 250px

| image_caption = Mansfield Dam, November 2018

| name_official = Mansfield Dam

| dam_crosses = Colorado River

| res_name = Lake Travis

| location = Travis County, Texas, USA

| operator = Lower Colorado River Authority

| dam_length = {{convert|7089|ft|m|0}}

| dam_height = {{convert|278|ft|m|0}}

| dam_width_base = {{convert|213|ft|m|0}}

| spillway_type = 24 controlled (paradox and jet-flow gates)

| spillway_capacity = {{convert|abbr=on|130,000|ft3/s|m3/s}} (23 floodgates at 5,250 cfs; 1 variable discharge gate at 2,285 cfs 2 turbines at 4,100 cfs, 1 turbine at 2,400 cfs)

| construction_began = 1937

| opening = 1941

| demolished =

| cost =

| res_capacity_total =

| res_catchment =

| res_surface =

| plant_turbines =

| plant_capacity = 108 MW

| plant_annual_gen =

| coordinates = {{coord|30|23|32|N|97|54|26|W|type:landmark|display=inline,title}}

| extra =

| website =

}}

Mansfield Dam (formerly Marshall Ford Dam) is a dam located across a canyon at Marshall Ford on the Colorado River, {{convert|13|mi|km|0}} northwest of Austin, Texas. The groundbreaking ceremony occurred on February 19, 1937, with United States Secretary of the Interior Harold L. Ickes attending. The dam was a joint project by the Lower Colorado River Authority (LCRA) and the United States Bureau of Reclamation, with partial funding provided by the Public Works Administration. Brown and Root, headed by James E. Walters, Sr., was the prime contractor.{{Cite web|url=https://www.lib.utexas.edu/taro/ricewrc/00054/rice-00054.html|title=Guide to the Brown & Root / George R. Brown Executive Files, 1937-1978 MS 488|website=www.lib.utexas.edu|language=en|access-date=2017-03-22}} The dam was completed in 1941. Originally called Marshall Ford Dam, the name was changed in 1941 in honor of United States Representative J.J. Mansfield. The reservoir behind Mansfield Dam is named Lake Travis. The dam is owned and operated by the LCRA.

File:Dedication monument Mansfield Dam.jpg

Mansfield Dam is {{convert|278|ft|m|0}} high, {{convert|7089|ft|km|0}} long, and {{convert|213|ft|m|0}} thick at the base. The concrete gravity dam with embankment wings and saddle dikes was designed to control flooding; to store 1.4 km³ (369 billion US gallons) of water; and to generate hydroelectric power (108 megawatts). The Spillway Elevation is {{convert|714|feet}} above Mean Sea Level (MSL). LCRA begins to open floods gates when water reaches 681 feet above MSL. At {{convert|681|feet}} above MSL, discharge capacity exceeds {{convert|130,000|ft3/s}} as the lake rises.

The two lanes of Mansfield Dam Road, formerly RM 620, traverse the top of the dam, but traffic other than service vehicles are now prohibited. 620 was rerouted in 1995 to a four-lane highway bridge on the downstream side of the dam built for increase in traffic due to the popularity in Austin of recreating at Lake Travis.{{Cite web|url=https://bridgestunnels.com/location/mansfield-dam-road-formerly-tx-ranch-to-market-road-620/|title=Mansfield Dam Road (Formerly TX Ranch to Market Road 620) - Bridges and Tunnels |website=bridgestunnels.com|date=6 February 2020 |language=en|access-date=2022-06-08}}