SI-3D (3/15/05 version)
Overview, "As Is" Stream Integrity Situation: Primary Headwater Streams

Assessing Primary Headwater Streams

Primary Headwater Stream Classification

Current Ohio water quality standards define a headwater stream as a stream with a watershed of 20 square miles or less. These habitats have specific biological criteria for fish (IBI) (PDF 1164kb) and benthic macroinvertebrates (ICI) (PDF 801kb) that vary by ecoregion. However, the concept of fish community integrity does not accurately reflect conditions in primary headwater streams (drainage area less than 1 square mile and deepest pools less than 40 cm) where fish species richness is naturally low. In addition, the use of Hester-Dendy artificial substrate samplers to sample benthic macroinvertebrates, as required by the ICI protocol is usually not possible in primary headwater streams because water depth is not sufficient.

Consequently, from 1999 to 2002, Ohio EPA surveyed over 300 primary headwater streams in the various ecoregions of Ohio. In general, the results of the survey indicate that three distinct types of biological communities are present within the spatial scale of primary headwater habitat, dependent on interactions of hydrology, water temperature, stream flow, channel morphology, and type of stream bed substrate.

  • Class I: stream channels that are completely separated from ground water aquifers, and consequently only maintain water during or immediately after precipitation events. Because Class I streams naturally have a dry channel between weather events, the have low aquatic biological diversity.
  • Class II: stream channels that are hydrologically connected to perched ground waters and tend to have warmer water temperatures during the summer months. Class II habitat lack the fish and amphibian indicator groups that are found in Class III streams and have a low number (less than three taxa) of cool water adapted macroinvertebrates.
  • Class III: stream channels that are hydrologically connected to deep, cold, perennial ground water flow and that have at least one of the following biological signatures:
    • A high number of cool water benthic macroinvertebrate taxa;
    • Coldwater adapted fish species such as trout, mottled sculpins, and redside dace;
    • Salamander (amphibian) species with long-lived larval periods.

Causes Of Impairment

The major causes of primary headwater habitat impairments, in urban, suburban, and rural areas alike, are habitat modification and hydromodification. Specifically, fundamental changes to stream channel form through channelization, rip rap or gabion installation, lining with concrete, and/or conversion to a grassed waterway and elimination of primary headwater streams through filling, culverting, or disconnection from ground waters are the major ongoing impacts. Because the drainage areas are so small, each individual impact may seem minimal. However, collective impact of eliminating thousands of feet of primary headwater streams in a particular watershed can fundamentally alter the entire watershed. The example shown here is the Mill Creek Watershed in northeast Ohio, near Cleveland. These slides are from a presentation by Ohio EPA, Division of Surface Water, on their work with primary headwater streams.

Assessment Results

  • Lake County SWCD
    The Lake County SWCD is conducting a comprehensive water quality investigation of stream conditions throughout the county, with a particular focus on primary headwater streams. As data is collected it is entered into a data-base, used to generate GIS maps, and displayed on a website for local residents to access. Lake County has used this project to talk to local jurisdictions about development patterns, land use controls, and the measured effects of urban growth.
  • Rocky River
    A link to the Rocky River information is also found on the Cuyahoga County Board of Health’s Water Quality Program web page.
    In 2002, the Cuyahoga County Board of Health conducted a primary headwater assessment of 19 streams in the North Royalton portion of the Rocky River watershed. Streams were only sampled at least 24 hours after the last rainfall to insure base flow conditions were present. Five percent of streams sampled were Class I, 26% were Class II, and 69% were Class III primary headwater habitat.
  • Summit County Zoning Law
    In 2002, Summit County passed a zoning ordinance that requires riparian protection for all primary headwater habitat streams.