The following are documents that can assist local governments in adopting and implementing iSWM practices and developing a comprehensive stormwater management program.

Also check our our training page for detailed training on iSWM principles and general stormwater management best practices.

Other iSWM Related Documents

Memo on Hydrologic Mimicry Research

The iSWM Criteria and Technical Manuals do not provide guidance for planning and design for hydrologic mimicry. This memorandum includes research on previous hydrologic mimicry cases.

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Memo on Forebay Design Guidance

Guidance on wet pond inflow forebays for municipalities. The current iSWM Manual includes several options for dry pond outfalls that are not submerged. Outfalls that are submergered within a wet pond present specific challenges. Inflow forebays in ponds provide energy dissipation and water quality benefit to flows entering basins. The following memo outlines the advantages and disadvantages of differnt types of forebays and introduces considerations for additional guidance on forebay desing and maintenance.

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BMP Summary Pages for Site Development Controls

BMP Summary Pages for Site Development Controls including: Multi-Purpose Detention Areas, Organic Filter, Green Roof, Proprietary Structural Controls, and Open Conveyance Channel.

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Economic Benefits of iSWM

Brief educational documents, which were produced to capture the economic benefits of iSWM in brief, concise, 1-page summaries. These are inteded to be used as promotional material for non-technical individuals by emphasizing holisitic impacts long term for different scales of implementation, stressing value of full regional participation. These documents also provide commentary and summarized case studies from participating communities.

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Guidance on Developing a Regional Detention Program

Many communities throughout the NCTCOG region have expressed an interest in developing a regional detention program. Regional detention options presented in this memorandum include considerations for site locations, water quality, potential funding options, and implementation. In developing a regional detention program and this guidance document is intended to help inform the process.

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Research of Volumetric Detention and Channel Protection Volume Design Guidance State of Practice

This memo reviews the current state of practice for the design of extended detention systems and the determination of channel protection volume storage requirements and associated allowable discharge rates and drawdown times both regionally and nationally. This memo compares the following city and agency criteria and compared it to the current iSWM Criteria Manual and Technical Manual Guidance: Austin, TX, San Antonio, TX, Fayetteville, AR, Tulsa, OK, Little Rock, AR, and Harris County, TX.

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Re-evaluation of 85th Percentile Rainfall Requirements

This memo re-evaluates the 85th-percentile storm runoff capture as stipulated in the iSWM Technical Manual. Long-term rainfall hourly data at National Climactic Data Center (NCDC) stations in the NCTCOG region was analyzed using the Urban Watersheds Research Institute (UWRI) Water Quality Capture Optimization and Statistics Model (WQ-COSM).

This memo is for informational purposes only. The methods referenced in this memo have not been adopted into the iSWM Criteria or Technical manuals.

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5-year Outreach and Implementation Strategy

This 5-Year Outreach and Implementation Strategy is a result of a collaboration between the North Central Texas Council of Governments (NCTCOG), consultants, and the iSWM Implementation Subcommittee with the intent to increase awareness of iSWM and iSWM principals. Identify key agencies, personnel and stakeholders to engage through community outreach, plan for continuous improvement to the program’s technical content and training program and, refine the vision and messaging plan to be implemented over the next 5 years.

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Proprietary Device Memo

This memorandum provides supplemental guidance for communities in the region for the evaluation of post-construction stormwater BMP proprietary devices. This document supplements Section 26 of the Site Development Controls Chapter in the iSWM Technical Manual and documents the assumptions and processes for preparing this information.

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Comparison of Maintenance and Inspection Methods

This memo summarizes our findings related to ownership, maintenance and inspection methods, waste management, appeals, variances, and enforcement actions. The intent is to provide a thorough description of how other cities and counties across the country are addressing these issues in their ordinances so that cities adopting iSWM might have a useful reference to develop their own water quality ordinance.

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Watershed-Based Stormwater Planning

Stormwater master planning is an important tool with which communities can assess and prioritize both existing and potential future stormwater problems, as well as use to consider alternative stormwater management solutions. A stormwater master plan is prepared to consider, in detail, what stormwater management practices and measures are to be provided for an urban drainage area or a large development project.

Multi-objective stormwater master planning broadens this traditional definition to potentially include land use planning and zoning, water quality, habitat, recreation, and aesthetic considerations. The broadest type of stormwater master plan is the comprehensive watershed plan which is described in detail in this resource guide.

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Floodplain Management

Floodplain management involves the designation of flood-prone areas and the limiting of their uses to those compatible with a given degree of risk. It is also aimed at minimizing modifications to streams, reducing flood hazards, and protecting the water quality of streams. As such, floodplain management can be seen as a subset of the larger consideration of surface water and stormwater management within a local community.

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Dam Safety and Water Rights

The Texas Commission on Environmental Quality (TCEQ) is responsible for administering state dam-safety laws. TCEQ has four primary areas of activity in the dam-safety program: (1) safety evaluations of existing dams, (2) review of plans and specifications for dam construction and major rehabilitation work, (3) periodic inspections of construction work on new and existing dams, and (4) review and approval of emergency action plans.

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Economic & Environmental Benefits of Stewardship Tool

The Economic & Environmental Benefits of Stewardship tool can estimate the return on investment of implementing environmental stewardship to reduce the environmental effects of transportation projects. The tool can educate decision-makers about the value of environmental stewardship.

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