Water Resources – Channel Study

The main stream channels within the Elm Creek watershed have been impaired by land development and communities are faced with a growing number of costly stream repair projects and loss of natural resources.  The Second Generation Elm Creek Watershed Management Plan adopted by the Commissio n in 2004 identified streambank instability as the top priority issue to be addressed by the Commission.

The Elm Creek Channel Study recommends revised management practices to provide for more stable conditions for Elm Creek, including Rush Creek, North Fork Rush Creek and Diamond Creek, as the watershed continues to be impaired by land development.  These revisions were adopted by the Commission as an amendment to the Commission’s Watershed Management Plan in March 2008.

The Channel Study was comprised of the following:

1.         Site survey of 45 channel locations.

2.         Hydraulic analysis and determination of bankfull channel capacity (considered to be the stable condition) at the surveyed locations.

3.         Hydrologic modeling of current watershed to estimate the frequency of bankfull flow at each location.

4.         Assessment and recommendations of watershed management practices to reduce the input of stream stability based on future conditions as the watershed continues to develop.

The Channel Study stated the following conclusions:

1.         Many stream channels have been impacted by development.

2.         The current watershed management requirements have not been adequate to reduce flow from development to provide for a stable channel.

3.         Additional watershed management requirements are needed to address channel stability.

4.         Extended detention and reduction of surface water runoff should be implemented by the Commission to maximize channel protection.  Also, low impact design techniques and infiltration practices are encouraged wherever possible to reduce the need for extended detention.

The Channel Study has been broken down into four parts and appendices for ease of download:

            Part 1

            Part 2

            Part 3

            Part 4

            Part 5

            Appendices