The Cosumnes River is important in the state as the only Sierra river that flows with no major dams or diversions
from its headwaters to the Valley floor. It’s often studied as a “reference river” to compare river conditions with rivers like the Mokelumne that have large dam systems in place that alter flows and affect aquatic life. The Cosumnes already goes dry downstream of Plymouth in the summer, and we and other conservation groups are concerned about the potential impacts of greater diversions on the river.
In late July, the Plymouth City Council approved a long-term agreement with the Shenandoah Management Company LLC that gives the company the right to market water from the Cosumnes River and tributary streams that is conveyed to Plymouth through the Arroyo Ditch. Proceeds from the sale of water would be split 50-50 with the city.
The agreement obligates the LLC to maintain and operate the ditch and also to defend any challenges to the city’s claimed pre-1914 water rights to the Cosumnes and its tributaries. As far as we can tell, the city’s claim to the water has never been confirmed by a court. Until that is done, the “right” is only a claim and subject to legal challenge.
In an interesting twist, the city had not signed the agreement a few days after the council approval, and may not yet have done so. The LLC canceled its state registration in 2011. While the principals claim that they are going to revive the LLC, as of mid-August there was no evidence of that on the Secretary of State’s website.
We are working with local landowners, conservation organizations and others to follow the progress of this agreement and further research Plymouth’s claimed water right.