A watershed is the geographic region that drains into a body of water and is defined by the landforms and water flow. Hills and valleys direct water to a drainage basin such as a river or lake.

photo of Euclid Creek
Shaded waterways contribute to healthier ecosystems through cooler water temperatures.

The rivers and streams of Cuyahoga County and their many tributaries give structure to the natural systems and ecology of the County. They have contributed to development patterns, and influenced where we live, work, and play. Watersheds can be small, such as the area that drains into the creek behind your house. They can also be large; consider all the land, streams and rivers that drain into the Ohio River or Lake Erie. The Watersheds layer of the Greenprint provides two depictions of local watersheds:

  • Local watersheds named and grouped according to their major watershed “parent”.
  • Local Watersheds by Percent Impervious: Watersheds are shaded according to the percentage of impervious surface, a key indicator of watershed health and for appropriate practices.

image of healthy valleyUrbanization often brings an increase in hard surfaces, or impervious cover, which changes watershed hydrology by increasing water runoff volumes. As rain falls on hard surfaces, such as rooftops and parking lots, it often picks up pollutants, delivering them directly to the stream and decreasing water quality. Reducing the amount of impervious cover in a watershed can help improve the water quality significantly. Studies conducted by the Center for Watershed Protection (Impacts of Impervious Cover on Aquatic Systems) show a correlation between impervious cover and stream degradation. The chart below aggregates the results of these studies including the finding that an impervious cover greater than 25% can significantly damage stream functions and reduce water quality. Although every stream has a different threshold, these universal findings demonstrate a pattern and correlation.

Percentage of
Impervious Cover
Level of ImpactWater Quality
0-10%SensitiveGood Water Quality
Supports Aquatic Life
10 – 25%ImpactedMarginal Water Quality
Can support aquatic life
Greater than 25%DamagedPoor Water Quality
Channel eroded or modified
Limited aquatic life

Importance and Value

Watersheds include the water features, wetlands, steep slopes, and flat floodplains of a geographic region. Overall, healthy watersheds provide important services of “Nature” to a community at no-cost, including:

  • Stabilizing stream erosion
  • Minimizing flooding, an important attribute given more frequent and increasingly severe storm events due to climate change
  • Providing recreational opportunities
  • Protecting the unique geography and “Nature’s” history of the county.
  • Contributing to the aesthetic beauty of a community and the desirability of Cuyahoga County as a place to live, work, and visit.

Recommendations for Communities and Landownersimage of Willow West Creek

  • Develop a state-endorsed Watershed Balanced Growth Plan
  • Manage stormwater at regional level through the Northeast Ohio Regional Sewer District’s Stormwater Master Plans. Needs a link
  • Limit soil erosion on construction sites through best management practices (minimize extent of disturbance, temporary seeding, etc.) to keep soil particles in place and reduce the amount of sediment flowing into streams.
  • Re-establish natural infiltration, e.g. create rain gardens or bioswales that allow water to filter through the soil naturally.
  • Separate storm sewers and sanitary sewers to eliminate the combined sewer overflow of wastewater with rainwater into the watershed rivers and lakes.
  • Restore the natural biological and physical systems of a watershed through tree plantings, bioengineering, floodplain enhancement, etc.
  • Remove invasive species and plant native species to limit the harmful effects of non-native species and help increase biodiversity of the ecosystem and watershed.
  • Create sustainable landscapes and reduce the size of grass lawns with native plants and trees.
  • Develop green connections between various beneficial natural areas (e.g. parks) to ensure wildlife movement and migration throughout the County.
  • Utilize Low-Impact Development practices that help to mimic the natural environment and ensure pre-development hydrology is reached at site completion.

Resources for More Information