Posting Language
Title
Authorize negotiation and execution of an interlocal agreement with the Texas Water Development Board for sedimentation and bathymetric surveys of Lake Austin and Lady Bird Lake for a total contract amount not to exceed $107,038. Funding: $107,038 is available in the Fiscal year 2024-2025 Operating Budget of Austin Water.
De
Lead Department
Austin Water.
Fiscal Note
Funding in the amount of $107,038 is available in the Operating Budget of Austin Water.
Prior Council Action:
August 7, 2008 - Council approved Resolution No. 20080807-046 authorizing negotiation and execution of an interlocal cooperation agreement with the Texas Water Development Board (TWDB) for a volumetric survey of Lake Austin in an amount not to exceed $20,628.
August 7, 2008 - Council approved Resolution No. 20080807-047 authorizing negotiation and execution of an interlocal cooperation agreement with the TWDB for a volumetric survey of Lady Bird Lake in an amount not to exceed $19,981.
February 25, 2010 - Council approved Resolution No. 20100225-055 authorizing negotiation and execution of an interlocal cooperation agreement with the TWDB for a volumetric survey of Lake Austin, in an amount not to exceed $5,157.
February 25, 2010 - Council approved Resolution No. 20100225-054 authorizing negotiation and execution of an interlocal cooperation agreement with the TWDB for a volumetric survey of Lady Bird Lake in an amount not to exceed $4,995.25.
For More Information:
Heather Cooke, Austin Water Chief Administrative Officer, 512-972-0083 or heather.cooke@austintexas.gov.
Council Committee, Boards and Commission Action:
May 21, 2025 - Recommended by the Water and Wastewater Commission on an 8-0 vote with three vacancies.
Additional Backup Information:
The TWDB will perform sedimentation and bathymetric surveys of Lake Austin and Lady Bird Lake. A bathymetric survey will entail collection of bathymetric or depth measurements to develop an updated elevation-area-capacity table and associated contour maps. While a bathymetric survey only identifies the current bottom surface of a reservoir, a TWDB sedimentation survey identifies the pre-impoundment surface of the reservoir as well. Sediment core samples are collected throughout the reservoir and correlated with multi-frequency acoustic data signal returns to aid in the identification of the pre-impoundment surface. A sedimentation survey report includes updated elevation-area-capacity tables, a bathymetric contour map, a sediment volume and annual average sedimentation rates, and a map of sediment thicknesses throughout the reservoir. These surveys will also include three dimensional scans of Austin water intake structures at Ulrich Water Treatment Plant, Davis Water Treatment Plant, and the abandoned intake structure at the decommissioned Green Water Treatment Plant. The last bathymetric survey of these lakes was completed in 2008. An updated survey will provide information relating to accumulation and loss of sediment in creek deltas and along the lakeshore and to changes in lake volume. The most recent survey did not include a sedimentation survey or scans of water treatment plant intakes. This data will help water resource projects meet the needs outlined in Water Forward, Austin Water’s 100-year integrated water resource plan, and in other water resources planning efforts.