City Creek Nature Notes – Salt Lake City

March 13, 2017

March 13th

Filed under: Butterfly, gnats, People, Robin, Spider — canopus56 @ 7:27 pm

Flooding of City Creek’s Delta – Part IV

External Link to Image

Source: Natural Resources Conservation Service (2017). SNOTEL Reporting System (data); Salt Lake Tribune, April 29, 2011 and June 1983. The horizontal lines represent in acre-feet per month, the capacity of North Temple storm water conduit and the State Street City Creek conduit before and after the floods of 1983.

4:00 p.m. It is another warm Monday, and the canyon, which usually will be empty on first workday of the week, is still overflowing with walkers, families, groups of hiking young men, runners, and bicyclists. It is the pent up energy dissipating from winter indoor living. From this influx of people who do not regularly visit the canyon, a collection of clothing builds up pinned to the community posting board at the gate: a glove, a case for glasses, a winter dog sock, a child’s sock, a hat, a sweater, some socks. It is seven days to spring, and March, like February, is turning out unseasonably hot. The high temperatures end the “Great Concentrator” (Dec. 29): the cold of winter. Four early orange brown butterflies are seen, and backlighting from the down-canyon Sun reveals many gnats and the silk of spiders in the trees. The chickadees have dispersed along with other birds, and the canyon has little bird life other than two robins at Guardhouse Gate. At mile 0.3, there is small cultivar tree next to the road that is covered in galls, and none of the surrounding trees have been attacked. Near mile 0.2, I notice a young red osier dogwood that at the end of one small twig has formed an enormous one inch gall. This is the immune system of trees and bushes at work.

While earlier City Creek delta flooding events can be partially attributed to inadequate or technological limits of civil engineering and political disputes of the time, another major lesson of northern Utah flooding through the 1930s is that the flooding was caused by denuding watersheds of trees and grasslands through lumber production and sheep and cattle grazing (Honker 1999 at 32-39, Cottam 1947). By the 1930s, over four million sheep and cattle grazed in Utah (Cottam 1947). On May 30th, 1926, E.C. Shepard, the supervisor of the Wasatch National Forest, and Frederick S. Baker, forest examiner, reported that in Utah, 434,404 cattle, 2,821,308 sheep and 20,000 horses grazed on forest lands (Salt Lake Telegram, Cottam 1947). Baker credited water protection against over-grazing as to why City Creek did not flood as severely as torrential floods in Willard and Farmington. In response to the floods of the 1920s and 1930s, numerous studies found that removal or small areas of coverage at the headwaters of Wasatch Front Range canyons through improper grazing practices leads to devastating downstream floods during extreme weather events (Bailey, Cottam 1945, Forsling, Utah Flood Commission).

Historically, severe floods in northern Utah have led to a cycle of report generation (e.g. Potter, Bailey, Cottam 1945, Utah Flood Commission), reform proposal (e.g. Utah Flood Commission, Cottam 1945), and subsequent public amnesia and inaction (Honker 1994, 1999, Park). The floods of the late 1800s led in the early 1900s to proposals for a forest reserve system (Park) and Interior Secretary Pinochet establishing Utah national forest reserves, including the Wasatch Cache National Forest (Honker 1999). On 1894, a new City administration adopted a maintenance program to regularly clear City Creek’s bed of tree debris (Salt Lake Herald, January 31, 1894). Floods of the early 1900s led to transfer of watershed authority in City Creek and the other Salt Lake valley canyons to the City in order to promote culinary water protection and reforestation (Public Law 63-199, Public Law 73-259). The U.S. Forest Service established a tree nursery in Big Cottonwood Canyon that produced up to four million seedlings per year for use throughout Intermountain west forests (Intermountain Republican, April 23, 1908). The City adopted numerous watershed protection practices and partially reforested City Creek, but not Emigration Canyon (Salt Lake Tribune, May 1, 1918).

After each flood, the lesson of the need to preserve and reforest trees and vegetation at the headwaters of all of the Salt Lake Valley canyons was forgotten. In 1902, Albert Potter of the United States Forestry Division toured Utah and surveyed the conditions of public and and the attitudes of local farmers and ranchers towards conservation (Potter; Honker 1994). He recorded how Utahans after flood of the late 1800s and early 1900s made the connection between denuding canyons through livestock grazing and lumbering and subsequent flooding, and while some supported conservation, many maintained the necessity for continued grazing. From historical records, Hull estimated that Great Basin ranges were stripped of their native perennial grasses and were replaced from larger sagebrushes and saltbrushes in 10 or 15 years (Hull 1976, cited in Barbour and Billings 2000 at pp. 263-264). From the early 1880s to the 1920s, over a million sheep grazed in northern Utah, denuded the landscape, and several hundred thousand made an annual trip down Emigration Canyon (Cottam 1947; Potter; Bailey). Fires were intentionally set to clear areas of trails and grazing (Utah Flood Commission at 42-43). That led to the floods of the late 1920s and early 1930s. From the 1900s to the 1940s, City Creek remained a popular escape for numerous City residents from the summer heat and vegetation suffered from over-use (Hooten). From the 1950s to the 1960s, the City closed City Creek to all public entry as a water quality protection measure and to give the canyon time to renew lost vegetation (Hooten). But the City grew lax in its clearance of tree debris from the City Creek stream bed, and in the floods of 1983, tree debris clogged the main storm water sewer and flooded the business district. Explosives had to be used to clear the blockage (Salt Lake Tribune, June 1983).

After the flood of 1983, the City designated City Creek as a permanent recreation and watershed recreation area (Salt Lake City 1986), installed the flood retention ponds at Bonneville Drive and the canyon entrance to trap tree debris, and increased the capacity of the underground conduits that move City Creek past downtown from 90 cubic feet per second to 210 cubic feet per second (Salt Lake Tribune, April 29, 2011 and June 1983) by expanding the conduit under North Temple Street. In terms of monthly flows, the new monthly discharge capacity of 12,495 acre-feet per month comfortably exceeds historic maximum monthly flow of 8,358 acre-feet (Natural Resources Conservation Service SNOTEL data, 2017), but the daily discharge capacity of 210 cubic feet per second is far below the maximum recorded daily discharge rate of 322 cubic feet per second (Salt Lake City Dept. of Public Utilities 2017).

Another opportunity to expand the discharge capacity of the storm sewers were passed up. In 2003, the City received a $50,000 USD grant to examine raising City Creek from its underground conduit and having a raised streambed exit the City along North Temple through the westside (Deseret News, Aug. 1, 2003). A more detailed plan by the Army Corps of Engineers envisaged moving City Creek along North Temple from 300 West to the Jordan River along a proposed abandoned railway in an large urban park (Love 2007), but the estimated cost was $20 million USD (Deseret News, Aug. 1, 2003), and nothing was done. Through 2017, the railway line was not abandoned, the westside was made the site of a regional commuter rail hub, and the railway is an even more important hub of the City’s freight and regional transportation infrastructure. By dedicating this western exit route to other purposes, future efforts to find a wider bed with enough capacity to carry City Creek’s flood waters past the downtown will be more expensive and complex. That increased capacity will be need seems likely given the new Bekker et al 2014 estimates for peak storm and flood events (March 16th).

Since the post-1983 improvements, the City has grown lax in removing tree debris and the creek bed between Guardhouse Gate and milepost 1.5 is refilling with fallen trees (Personal observation). Although City Creek is now a nature preserve where no timber clearing occurs, in other Wasatch Canyons, large ski resorts and residential cabins have renewed the process of removing trees (Personal observation).

In Thoreau’s “Journal” on March 13th, 1858, he comments that morning skies have a deeper red color. On March 13th, 1855, he finds four mice nests where the snow has retreated. On March 13th, 1859, he sees a small flock of blackbirds.

On March 13th, 1920, the Salt Lake Herald urged the creation of a public park at the mouth of City Creek Canyon.


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