Watershed Rehabilitation Program in Texas 1
Dams Constructed by Year (nationwide) 700 600 500 PL-566 Pilot/RC&D PL-534 400 300 200 100 0 48 51 54 57 60 63 66 69 72 75 78 81 84 87 90 93 96 99 Year 2 Number of Dams
Watershed Construction in Texas First FRS Built in 1948 Construction Peaked During the 1960 s 2,000 Dams were constructed in Texas under the Small Watershed Program. Most were constructed in rural, agriculturally based areas. 3
Watershed Dams in Texas (as of 2007) 2,000 Dams constructed in Texas 208 Dams meet or exceed evaluated life 120 Dams in need of repair 4
Number of Floodwater Retarding Structures Surpassing Evaluated Life in Texas Cumulative No. of Dams 1200 1000 800 600 400 200 208 269 339 460 542 648 792 907 984 1066 1130 0 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Year 5
Number of Floodwater Retarding Structures Surpassing Evaluated Life in Zone 1 50 Cum ulative No. of Dam s 45 40 35 30 25 20 15 10 5 0 0 0 0 3 13 18 38 42 42 42 44 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Year 6
Number of Floodwater Retarding Structures Surpassing Evaluated Life in Zone 2 140 Cumulative No. of Dams 120 100 80 60 40 20 26 42 59 80 93 102 109 117 119 122 126 0 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Year 7
Number of Floodwater Retarding Structures Surpassing Evaluated Life in Zone 3 120 Cumulative No. of Dams 100 80 60 40 20 0 89 92 97 85 76 59 49 41 30 22 17 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Year 8
Number of Floodwater Retarding Structures Surpassing Evaluated Life in Zone 4 70 Cumulative No. of Dams 60 50 40 30 20 10 0 58 55 47 35 30 25 27 20 7 7 7 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Year 9
Number of Floodwater Retarding Structures Surpassing Evaluated Life in Zone 5 Cumulative No. of Dams 900 800 700 600 500 400 300 200 100 0 755 805 687 628 539 442 362 316 243 158 198 2007 2008 2009 2010 2011 2012 2013 2014 2015 2016 2017 Year 10
Hazard Classification (as of 2007) 218 - Number of High Hazard dams 122 - Number of currently High Hazard dams originally designed and built as Low or Significant Hazard. Primary reason for upgrade is urban development downstream within breach area. 11
Issues and Concerns Public safety and health Replacing or repairing failing components Sediment storage - 50 yr. minimum Urban development below or near dams Upgrades to current safety criteria 12
Urbanization and Floodplain Development 13
Slope Failures 14
Downstream Development 15
Principle Spillway Deterioration 16
Sediment Pool 17
Section of a Typical Floodwater Retarding Structure Storage in Pool Top of Embankment Sediment Storage Flood Storage Embankment Auxiliary Spillway Crest Principal Spillway Crest 18
Rehabilitation Amendment The Small Watershed Rehabilitation Amendments of 2000 (Section 313, Public Law 106-472) provides the authority for rehabilitation. It amends PL 83-566 "Watershed Protection and Flood Prevention Act" to add authority for rehabilitation 19
Authority Provides: Technical assistance in planning Technical assistance in application Federal cost share - 65% Sponsors (SLO) cost share - 35% (part of SLO cost share can be in-kind) 20
Eligible Watershed Projects Approaching 50 years old Have safety concern Hazard classification increased O&M must be adequate Application made through State Agency Applications ranked for priority 21
Rehab Process Sponsors make application NRCS develops Plan of Work NRCS develops Plan/EA Public review by State, Federal, interested individuals Publish FONSI in Federal Register (Finding Of No Significant Impact allows EA instead of EIS) Plan/EA approved by NRCS Chief 22
Planning Process Steps Identify problems and opportunities Inventory and forecast resource conditions Formulate alternative plans Evaluate alternative plans Compare alternative plans Select final plan 23
Typical Planning Process Scenarios No Action (Controlled Breach by SLO) Decommissioning of Dam (Controlled Breach by NRCS) Relocation of Properties at Risk, Repair Dam Dam Rehabilitation - several alternatives 24
No Action Without federal funding and/or sufficient local funding, rehabilitation will not be viable. To reduce liability and eliminate the potential hazard of dam failure, a controlled breach measure will be implemented. The stream channel will be reconnected. Minimal effort will be made to stabilize sediment. 25
No Action (cont.) The structure will no longer provide protection or flood damage reduction benefits for any level of storm event. Contingency plans for catastrophic storm events will need to be developed and implemented downstream. 26
No Action (cont.) Additional work to downstream infrastructure (roads and bridges) may be needed due to increased flooding. Upstream property values may be negatively affected. 27
Decommissioning of Dam The footprint of the dam and spillway will be removed. The stream channel will be reconnected. Sediment may need to be stabilized by a grade stabilization structure or other means. Upstream property values may be negatively affected. 28
Decommissioning of Dam (cont.) No flood damage reduction or protection will be provided. Contingency plans for catastrophic storm events will need to be developed and implemented downstream. Additional work to downstream infrastructure (roads and bridges) may be needed due to increased flooding. 29
Relocation of properties at risk, repair dam The dam will not be rehabilitated, but may be repaired and operation & maintenance of the structure will continue. Residences, utilities, roads, and railroads within the breach inundation area downstream of the dam may need to be altered or relocated. 30
Relocation of properties at risk, repair dam (cont.) Measures should be taken to insure that the dam will remain at a low hazard classification and future downstream development limited and/or restricted. 31
Dam Rehabilitation Update dam to current NRCS and state criteria for a high hazard dam, or initiate zoning requirements to maintain low hazard classification. Maintain upstream property values. Aesthetic value will remain. Retain existing benefits and protection. 32
Dam Rehabilitation Alternatives May Include Raising top of dam. Installing additional principal spillway pipe. Additional earthen auxiliary spillway or hardened surface auxiliary spillway. Installing a downstream impact basin. Installing hooded inlet structure. 33
Additional Hooded Inlet Principal Spillway 34
35
Impact Basin 36
Roller Compacted Concrete Auxiliary Spillway 37
Local Input Advisory Committee Concerned Citizens Sponsors Others Preferably smaller group, 12 or less total members 38
Advisory Committee Duties Committee has input on the project. Insures community concerns are considered. Liaison between project effort and public. Input is considered during the development of the alternatives. The final decision concerning alternatives is to be made by the NRCS with sponsors input. 39
Budgets Plan/EA IS NOT a fund obligating document. Funding comes from annual Congressional appropriations. 40
Cost Sharing Alternative SLO NRCS No Action 100% 0% Decommissioning 35% 65% Relocation/Repair 35% 65% Dam Rehabilitation 35% 65% 41
More information about dam rehabilitation available NRCS dam rehabilitation website www.nrcs.usda.gov/programs/ws_reinvent 42
The U.S. Department of Agriculture (USDA) prohibits discrimination in all its programs and activities on the basis of race, color, national origin, age, disability, and where applicable, sex, marital status, familial status, parental status, religion, sexual orientation, genetic information, political beliefs, reprisal, or because all or part of an individual s income is derived from any public assistance program. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA s TARGET Center at (202) 720-2600 (voice and TDD). To file a complaint of discrimination, write to USDA, Director, Office of Civil Rights, 1400 Independence Avenue, S.W., Washington, D.C. 20250-9410, or call (800) 795-3272 (voice) or (202) 795-6382 (TDD). USDA is an equal opportunity provider and employer. 43
Natural Resources Conservation Service Questions? Rehabilitation Program 44