May 22, 2012 ASFPM - San Antonio Mike Moya, PE – Halff Associates Brian Reis, PE – RPS Espey Brian Wells, PE – MWM Design Group

 Purpose is to determine what Texas communities are doing above the minimum FEMA standards  Developed by members of TFMA & ASCE/EWRI  On-line survey from Aug ‘11 to Feb ‘12  Workshop was held Sept. ‘11 at TFMA’s fall conference

 Activities that could adversely impact another property or community will be allowed only to the extent that the impacts are mitigated or have been accounted for within an adopted community-based plan 3

4  Principle developed  NAI Toolkit  Legal Aspects of NAI  Coastal NAI funded by NOAA

 Physical increases ◦ Peak flow rates ◦ Frequency of bank full conditions ◦ Stormwater pollution ◦ Sediment transport (aggradation) ◦ Etc.  Physical reductions ◦ Base flow ◦ Infiltration ◦ Sediment transport (degradation) ◦ Etc.

 The NFIP Regulations mandate that participating communities adopt and enforce at least the minimum standards of 44 CFR 60.3 Reference: 44 CFR 59.2(c)  Communities may exceed the minimum standards and are encouraged to do so Reference: 44 CFR 60.1(d)

 When the NFIP was established in 1968, it was decided that minimum development standards would be required for participation  They were considered sufficient to establish a balance between an acceptable level of flood risk versus difficulty in conducting the local program Goal: Keep the program as simple as possible so more communities will enroll

 Even with the minimum FEMA standards, flood damages in the United States have continued to increase  “No Adverse Impact floodplain management is where the action of one property owner does not adversely impact the rights of other property owners, as measured by increased flood peaks, flood stage, flood velocity, and erosion and sedimentation.”

 Located between Austin and San Antonio  Population 45,000  Home of Texas State University  San Marcos River ◦ Popular recreation area ◦ Home to several threatened or endangered species  Texas Blind Salamander  Fountain Darter  Texas Wild Rice  Will be subject to EPA MS 4 regulations

Houston FW D SA Austin Amarillo El Paso Brownsville Laredo San Marcos

 25-year and 100-year are to be conveyed / contained within ROW or drainage easements  Peak flow shall not cause increased inundation of any building or roadway for the 2-, 5, 10-, 25-, 50- or 100-year storm frequencies.  Fully developed conditions upstream.  Detention is required for the 2- and 25-year frequency storm events.

 Development within the floodplain shall not increase the base flood elevation by more than 1 foot.  Development within the floodway shall not result in any increase in the base flood.  Floodplain alterations shall not create an erosive water velocity (> 6 fps) on- or off- site.

San Marcos

 Limits on impervious cover ◦ Slopes (i.e. 25%) ◦ Special areas: Edwards Aquifer, SM River Corridor ◦ Additional restrictions: water quality and buffer zones  Permanent BMPs ◦ Edwards Aquifer - limits increase in TSS to 20% ◦ SM River Corridor - capture first ½ inch

 San Marcos Comprehensive Planning ◦ In progress ◦ Land use suitability analysis ◦ Identification of environmental metrics ◦ Develop new sustainability standards: detention, drainage, erosion, sedimentation control, archeological site protection, etc. ◦ Consideration of Habitat Conservation Plan Goals  Habitat Conservation Plan, December 2011 ◦ Result of the EA Recovery Implementation Program ◦ Identifies species and habitat ◦ Identifies biological goals ◦ Includes ‘take’ coverage ◦ Activities required to minimize impacts

 USFWS to issue Incidental Take Permit based on HCP  Permittees ◦ San Marcos ◦ New Braunfels ◦ Texas State University ◦ Edwards Aquifer Authority ◦ San Antonio Water System (SAWS)  A collaborative, consensus-based stakeholder process.  Plan to protect the federally-listed species affected by the management of the Edwards Aquifer and other activities.  The goals of the HCP include contributing to the recovery of these species.

 Restoration of Texas Wild-Rice  Expanded program of monitoring water quality  Management of recreational use  Management of aquatic vegetation and litter  Control non-native and predator animal species  A program to register, permit and evaluate septic systems  Reduce impacts of IC through BMPs/LID  Etc.

The Corridor Development Certificate Process (CDC) affirms local government authority for local floodplain management and establishes a set of Common Regional Criteria and procedures with the goal of minimizing flood risks along the Trinity River Corridor in north central Texas

The Corps Regional Environmental Impact Statement Trinity River and Tributaries – 1988 (TREIS) determined that the cumulative impact of allowing individual development projects in the Trinity River floodplain could be both measurable and significant.

Corps of Engineers Record of Decision (1988)  No rise in the 100-year or SPF elevation for the proposed condition will be allowed.  The maximum allowable loss in storage capacity for the 100-year (0%) and SPF (5%)  Alterations in the floodplain may not create or increase an erosive water velocity on or off-site.”

Trinity River Steering Committee, facilitated by the NCTCOG.  Statement of Principles for Common Permit Criteria (January 1988)  Resolution for a Joint Trinity River Corridor Development Certificate Process (December 1988)  Regional Policy Position on the Trinity River Corridor (January 1989).  First edition May 1991

Common Regional Criteria  No increase in the 100-year flood water surface elevation (within 0.04 feet) and no significant increase in the Standard Project Flood water surface elevation  A maximum allowable decrease of valley storage in the 100-year flood and Standard Project Flood discharges of 0.0% and 5.0%, respectively  No creation, or significant increase, in erosive water velocity on-site or off-site

Benefits  Common Regional Criteria  Hydrologic modeling based on year 2050 Upper Trinity River watershed development  Hydraulic model incorporating CDC permitted floodplain development  U.S. Army Corps of Engineers technical review  Regional review and comment  Guarantee of local control of floodplain development decisions

 Questions 1.What standards apply to quantify adverse impacts? 2.What is considered to be an insignificant impact? 3.What mitigation measures are required? 4.Which storm events are regulated? 5.What physical / chemical properties are regulated? 6.What specific challenges have you encountered?  50 participants  Communities varied in size

50 respondents Yes Velocity and TSS

 No Policy  No increase allowed in Zone AE  No rise in floodway  Peak: 0 cfs – 10 cfs or 0% - 2%  Elevation: 0 ft. – 1.0 ft 1 foot rise no rise 0 cfs 0.00 feet

48 respondents  n/a

50 respondents  n/a

39 respondents TSS velocity HCP  n/a

 Educating developers, engineers, and politicians  Retention / Detention standards  Using preliminary data to regulate  New FEMA flood maps  Conflicting regulations of adjacent communities/districts  Defining “significant” impacts to upstream and downstream properties  Lack of enforcement  Consistency in Engineering methodologies  Regulating multiple storm frequency events

 Diane CalhounTFMA  Rob ConnellFEMA Region VI  W. H. Espey AAWRE, President-Elect  Nefi GarzaCity of San Antonio  Steve GonzalesASCE - San Antonio  Steve GrahamSan Antonio River Authority  John HewittTFMA Assistant Workshop Coordinator  Romin KhavariCity of Grand Prairie  Melinda LunaTX Section EWRI, Chair  Sharon MattoxVinson & Elkins, LLP  Sam Riley MedlockASPFM  Mike Moya TFMA Workshop Coordinator (Halff Assoc.)  Michael NewmanCity of Temple  Brian Reis TFMA Workshop Coordinator (RPS Espey)  Roy SedwickTFMA  Brian WellsTFMA Assistant Workshop Coordinator

EQ Recharge Zone San Marcos