Skip to main content

Stream Stormwater TMDL Development in Maine using Stressor Identification and Impervious Cover Analysis

Buy Article:

$17.50 plus tax (Refund Policy)

Or sign up for a free trial

Abstract:

How do you restore an urban stream impaired by nonpoint sources using the TMDL framework? During the 1990's Maine DEP began placing small urban streams on the 303(d) list that did not meet Maine's tiered aquatic life standards. These impairments were primarily due to 'urban runoff'. TMDL development requires a detailed description of the impairments and that means clarifying the source of the impairment. In order to determine the best method to achieve water quality standards, Maine selected 4 urban streams for intense data collection and subsequent analysis using EPA's Stressor Identification Process (SI). Ideally, the SI process would narrow down causal agents and identify a probable TMDL model to solve water quality problems. The SI process confirmed that the observed impairments resulted from many stressors, with stormwater as the common denominator. Multiple stressors do not fit well into the traditional TMDL loading analysis. Concurrent with Maine's efforts, EPA Region 1 engaged in a group process with the states to identify innovative TMDL methods to step up regional production of TMDLs. Stormwater emerged as a priority cause of impairment and therefore resulted in the development of the 'Impervious Cover Method'(IC), by ENSR, which defined a relatively simple TMDL analysis using impervious cover as a surrogate for stormwater impacts. Maine choose the IC approach for TMDL development since it offered a logical segue from the conclusions of the Stressor Identification Process. To apply this approach, Maine developed a specific policy that connected impervious targets to Maine's tiered water quality standards based on macroinvertebrate sampling results. The resulting TMDL defines a %IC targets and identifies the pollutant load as the existing %IC in the watershed. The wasteload and load allocations are defined as the %IC reductions needed to achieve the target, but attainment of water quality standards are the ultimate goal. The %IC reductions also serve as a restoration concept for the adaptive implementation of Best Management Practices (BMPs) within the watershed, to reduce stormwater impacts. The reaction from the Municipal Separate Storm Sewer System (MS4) communities was mixed; some acknowledged the approach as reasonable, while others took the reduction in impervious cover literally and considered the goals unreasonable. EPA, Region 1 encouraged Maine to pursue %IC TMDL approach, but EPA's technical and legal review has resulted in multiple revisions and delays. Final approval is still pending, but EPA is committed to resolving technical difficulties and approval is likely. Will this convoluted TMDL process answer the questions on restoration and attainment of water quality standards? Current community efforts developing watershed management plans are promising, but aquatic biological outcomes are difficult to predict.

Keywords: AQUATIC LIFE; IMPERVIOUS COVER; STRESSOR IDENTIFICATION; TMDL; URBAN STREAM IMPAIRMENT

Document Type: Research Article

DOI: https://doi.org/10.2175/193864707786619738

Publication date: 2007-10-01

More about this publication?
  • Proceedings of the Water Environment Federation is an archive of papers published in the proceedings of the annual Water Environment Federation® Technical Exhibition and Conference (WEFTEC® ) and specialty conferences held since the year 2000. These proceedings are not peer reviewed.

    A subscription to the Proceedings of the Water Environment Federation includes access to most papers presented at the annual WEF Technical Exhibition and Conference (WEFTEC) and other conferences held since 2000. Subscription access begins 12 months after the event and is valid for 12 months from month of purchase. A subscription to the Proceedings of the Water Environment Federation is included in Water Environment Federation (WEF) membership.

    WEF Members: Sign in (right panel) with your IngentaConnect user name and password to receive complimentary access. Access begins 12 months after the conference or event
  • Subscribe to this Title
  • Membership Information
  • About WEF Proceedings
  • WEFTEC Conference Information
  • Learn about the many other WEF member benefits and join today
  • Ingenta Connect is not responsible for the content or availability of external websites
  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
X
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more