When Frank Burton first settled his ranch along Roberts Road in Penngrove, he claimed that the trout in nearby Copeland Creek ran so thick that he could reach in and catch them by hand. For Burton and other early settlers in the 1850s, the creek’s abundance of fish and year-round fresh water made it a valuable resource. But they soon learned that Copeland Creek had a darker side. During heavy winter rainstorms, it jumped out of its usual streambed in the Russian River watershed and into the adjacent Petaluma River watershed, filling the river with silt and debris that contributed to flooding and impeded riverboat navigation.
Calls in Petaluma for finding a remedy to this “evil in the hills”—as the Petaluma Argus called it—began in the early 1860s. Those calls were raised again in the winter of 2018, after Copeland Creek jumped its banks along Lichau Road in Penngrove, spilling over into Petaluma. As in the past, addressing the problem was met with concerns over private property rights, state and federal regulations, and questions about funding.
Copeland Creek originates from Elphic Spring near the summit of Sonoma Mountain, naturally flowing onto the Santa Rosa Plain at the southern edge of the Russian River watershed. While winter storms annually drop an average 23 inches of rain on the valley plain, the top of Sonoma Mountain, literally scraping rain from passing storm clouds, averages 50 inches. Prior to the 1870s, rainwater flowed down Copeland Creek and fanned out into a large seasonal lake across parts of current day Cotati and Rohnert Park, providing a habitat for egrets, herons, ducks, amphibians, and trout.
The increasing development of farms on the plain led to large-scale draining of Copeland Creek’s seasonal wetlands. In the 1870s, a nine-mile channel was constructed to connect the creek with the main stem of the Laguna de Santa Rosa, ultimately feeding the creek into the Russian River. But the collection of sediment and storm debris that built up during winter storms tended to hinder the channel’s flood control function, contributing to Copeland Creek’s inclination to jump into the nearby Petaluma watershed. The channeling also appears to have brought about a steep decline of trout in the creek.
In 1872, Copeland Creek, along with two other year-round creeks that flowed down Sonoma Mountain’s west slope, Adobe Creek and Lynch Creek, became a primary water source for Petaluma. A diversionary dam built midway up Copeland Creek piped roughly half of the creek’s stream flow to Petaluma reservoirs. Even so, come rainy winter seasons, Copeland Creek failed to change its evil ways.
State engineer reports in 1896 and 1902 called for remedies for shoring up the creek’s banks, but ranch owners responded with threats of trespassing lawsuits. In 1914, the U.S. Army Corp of Engineers recommended constructing a retaining wall along the creek. In 1918, local congressman Clarence Lea secured an appropriation of $91,000 from Congress to build such a wall, as well as to widen and dredge the Petaluma River and construct a turning basin at the foot of B and C Streets. The Cotati Land Company, a large landholder, sued the city of Petaluma, arguing that the retaining wall would result in flooding of their Cotati farmlands. While the Petaluma River was dredged and the turning basin constructed, it doesn’t appear the retaining wall was ever built.
By 1940, 69% of Petaluma’s water supply was coming from Copeland and Adobe creeks, with the remainder from wells on the east side of town. In 1959, Petalumans approved a revenue bond that purchased the rights and assets of the private company that provided the city its water, including the 270-acre Lafferty Ranch that held the headwaters of Adobe Creek. The purchase however excluded the water rights to Copeland Creek.
In 1961, the city of Petaluma, pressed with growth demands, agreed to build an underground aqueduct that diverted Russian River water to town from the newly constructed Coyote Dam on Lake Mendocino. Subsequent water capacity was added in 1982 with the completion of the Warm Springs Dam. In 1992, Petaluma shut down its Sonoma Mountain water works due to earthquake concerns with Lawlor Reservoir.
In 2021, the City of Rohnert Park was awarded a $6 million FEMA grant toward the construction of the detention basin for Copeland Creek to help mitigate flood problems, with matching funds coming from the city’s development fees. Capturing storm water in the basin will allow a slower recharge of the groundwater while also creating habitat for fish passage, including steelhead trout.
Not so long ago, they ran so thick as to be caught by hand.
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Earlier versions of this article appeared in the Petaluma Argus-Courier, March 15, 2018, and also the Sonoma Mountain Preservation Newsletter, 2018.