Under this definition, the EPA has identified three categories of sources of nonpoint pollution from hydromodification activities that affect coastal waters:

• Channelization and channel modification: referring to river and stream channel engineering activities carried out to control flooding; improve navigation; improve drainage; reduce potential channel migration; or other practices that change the depth, width or location of waterways or embayments in coastal areas (such as the excavation of borrow pits, canals, and underwater mining). Channelization and channel modification activities can have far-reaching adverse effects on instream and riparian habitats by causing changes to water quality, morphology and channel composition, stream hydraulics, and hydrology.
• Dams: defined by EPA as "constructed impoundments that are either (1) 25 feet or more in height and greater than 15 acre-feet in capacity, or (2) 6 feet or more in height and greater than 50 acre-feet in capacity". Dams can have adverse impacts on the hydraulic regime, surface water quality, and stream or river habitats.
• Streambank and shoreline erosion: refers to the loss of fastland (land near the shoreline that is safely above the erosive zone of waves and tides) along nontidal streams and rivers (streambank erosion) and to the loss of beach or fastland in tidal portions of coastal bays or estuaries (shoreline erosion). Shoreline and streambank erosion can result in excessively high sediment loads and increased turbidity and nutrient levels which can adversely impact aquatic vegetation, shellfish beds, and tidal flats.

For more information on each of these sources, please refer to Chapter 6: Management Measures for Hydromodification of the EPA's Guidance Specifying Management Measures for Sources of Nonpoint Pollution in Coastal Waters.

Channelization and Channel Modification
Channel modification and channelization activities in Alaska's streams and rivers include those associated with placer mining, culvert and bridge projects, bank stabilization/river training projects, material removals, fishery enhancements, channel diversions/realignments, and dams and impoundments.

Dams
The majority of dams in Alaska are small, run-of-the-river (power production is dependent on the available supply of water) operations with uncontrolled spillway discharges. Dam operations in the state are commonly used for water supply storage or for the generation of hydropower. The dams in Alaska identified to have the greatest potential to adversely impact water quality are those used to form reservoirs for mine tailings.

Human-Caused Streambank and Shoreline Erosion
In Alaska, shoreline and streambank erosion resulting from human activities include foot-traffic, boat wakes, all-terrain vehicles, placer mining, poorly sited and constructed roads, airports, residential, commercial and industrial development, poorly designed river training structures and riparian vegetation removal.

The local ordinances in Alaska that relate to nonpoint source pollution from hydromodification activities are linked to the following table. The ordinances are grouped by the management measure they relate to. Management measures 47 and 48, below, address nonpoint sources of pollution caused by channelization and channel modification activities. Management measures 49-51 address nonpoint sources of pollution caused by dam operations. Management measure 52 addresses nonpoint sources of pollution caused by human-caused streambank and shoreline erosion.

Each ordinance is identified by municipality, ordinance title and reference number. Many Alaskan municipalities have codes of ordinances which are available online. Whenever possible, a direct link is provided to the local ordinance online. Otherwise, the ordinance text is available in PDF (Adobe Acrobat) format. A free copy of the application required to view and print PDF files can be downloaded at Adobe Acrobat READER.

For more information, contact Sally Cox, Planner, Department of Community and Economic Development, at 907-269-4614.

NOTE: The ordinances or sections of ordinances provided on these pages are not the official versions and are provided for informational purposes only. While every effort has been made to ensure accuracy of the information presented herein, if the most current version or precise language of an ordinance is required, it is recommended that you contact the municipality from which it came.