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Know Your Local Waters

mountain stream

Dense stands of native vegetation along Big Cottonwood Creek are critical to the health of this natural stream ecosystem.

Today, more than a million people call Salt Lake County home. In addition to being Utah’s population center, Salt Lake County is also an economic center for the entire Intermountain West. With increasing development, substantial stream alterations, and a population that is expected to reach 1.6 million by the year 2050, the watershed issues in Salt Lake County are complex and evolving.

For the most part, the mountainous areas of the County are uninhabited and forested public lands cover nearly half of Salt Lake County. These undeveloped lands are a great benefit to the health of our watersheds, and streams in most areas of the upper canyons remain in a relatively natural state. Extensive recreation activities in the canyons do, however, contribute to stream impacts, and mining activities (both historic and existing) have severely degraded water quality in localized areas throughout the canyons.

Development has been, and continues to be, concentrated in the foothills and valley floor. In fact, foothills are the zone of greatest urbanization throughout the Intermountain West. As a result, all waterways in these lower elevation areas of Salt Lake County have been degraded to some degree by human activities, some quite dramatically.

Life of an Urban Stream

Riparian

Of, pertaining to, or situated along the banks of a river or other body of water. [Riparian trees provide shade that keeps stream water cool.]

There have been numerous changes to streams in urban settings over time with increasing development and changes in the landscape. The first usually comes in the form of irrigation diversions, where “first in time, first in right” water law philosophy has dewatered (water completely removed) many a stream in the American West. Of the fourteen major creeks in Salt Lake County, several have sections that are seasonally dewatered for irrigation and culinary water use.

The second major change from urbanization comes from land use encroachment of the stream channel and floodplain. The width of the creek is usually decreased, but the most dramatic impact is often to streamside vegetation—called riparian vegetation. The entire ecology of the stream environment changes when native shrub and tree species are removed, and with this change goes the wildlife and a stream’s ability to control pollutants. Some of the most devastating habitat loss occurs where buildings, paved surfaces, and manicured lawns extend right up to the water’s edge.

Urban vs natural streamflow

The final dramatic change can occur years later when stream waters flow faster, volumes grow larger (with increased runoff from impermeable urban surfaces), and flooding increases at virtually every constriction, whether natural or man-made. This leads to a higher probability of erosion, degraded water quality, flooding, and property damage.

As development pressure continues to put any remaining riparian habitat at risk, a greater understanding and appreciation of the value of native vegetation and working with the natural functions of streams can lead to creative solutions for homeowners, developers and landscapers. This guide explores a variety of ways to help protect against and reverse the stresses that human activities put on stream ecosystems.

Common Stream Threats

  • Stream channel alterations reduce or eliminate streamside vegetation, and increase flooding and erosion potential.
  • Stream diversions reduce instream flows and can completely dewater streams.
  • Loss of native vegetation impacts food and shelter for wildlife, and reduces shade on the stream. Cool water is necessary to the survival of many fish and aquatic insects. Warm water also contributes to excess algae growth.
  • Bare stream banks are prone to erosion.
  • Increased storm runoff caused by impervious surfaces (pavement, rooftops, etc.) that prevent water from soaking into soils.
  • Excess soil erosion impacts water quality,
  • degrades aquatic habitat, and damages property. It also creates incised channels that disconnect a stream from its floodplain and affect ground water levels, reducing a stream’s ability to carry flood waters and degrading riparian vegetation.
  • Increased pollutants in storm runoff (oil, gasoline, fertilizer, pet waste, household toxics, trash, etc.) degrade water quality.
  • Excess nutrients (from fertilizers, pet and yard waste, and leaky septic systems) cause algae overgrowth, which uses up oxygen in water and impacts aquatic life.