Click here to read our full comments to the California Department of Water Resources on Humboldt County’s Groundwater Sustainability Plan Alternative. The excerpt below outlines one example of an adverse impact on the river resulting from unsustainable groundwater use.
Strangely enough, after a series of historically dry, hot years, in the last weeks of August 2014, the lower Eel River disconnected – ceased to flow on the surface – in the reach immediately above the river’s tidal bore, and pretty much smack in the middle of the Lower Eel Valley Groundwater Basin. Surface flows only reconnected when a pulse of water released from the two dams on the mainstem Eel River to assist steelhead survival in the warm upper river finally reached the lower river, approximately 170 miles downstream.
Among the fish unable to navigate the dried-up lower Eel were adult chinook salmon seeking their spawning grounds in the upper watershed. Chinook in the Eel generally begin to come upriver in early September, but they have been reported in late August. Adult coho and steelhead generally come into the system in later months. However, while juvenile chinook leave for the ocean in the spring of their birth year, both coho and steelhead must spend a year in freshwater before they can leave for the ocean. Thus, depletions of surface water in the lower Eel River during August risk impacts to migrating adult chinook, but also to resident juvenile coho and steelhead.
Faced with as clear an instance of a “significant and unreasonable adverse impact” on beneficial uses as one could ever hope to see – where water quality and habitat values were reduced to zero – Humboldt County seeks to deny any relationship between groundwater use in the Lower Eel Valley and the Eel River’s disconnection. Instead, it urges DWR to look upstream for reasons the river went dry.
“The primary anthropogenic causes of reduced streamflows in the Eel and Van Duzen Rivers are upstream diversions and changes in forest composition, both of which occur at a watershed scale. In addition, the stream channels are impacted by sediment deposits associated with the 1955 and 1964 floods.” (Alternative Plan, page 32)
But the river didn’t go dry upstream. It went dry in the losing reach of the Lower Eel, precisely where one might expect a depleted groundwater aquifer, strongly connected to surface flows, to have the greatest effect on surface flows. The Alternative Plan simply denies that a significant and unreasonable adverse impact occured. Further, the Alternative Plan denies that such an impact could recur: it provides no evidence as to how it will prevent “depletions of interconnected surface water that have significant and unreasonable adverse impacts on beneficial uses of the surface water.” (Water Code §10721)
It would be bad enough if there were just the one significant and unreasonable adverse impact on beneficial uses. However, while we can be quite certain that such an impact did occur in August 2014, the data presented in the Alternative Plan do not provide sufficient information to rule out the possibility that there were also significant and unreasonable adverse impacts on connected surface flows in other recent years. While it has not completely disconnected so dramatically as in 2014, the lower Eel has seen extremely low flows at the end of the dry season, as well as outbreaks of fish disease, in previous and successive years.
 See, e.g., https://lostcoastoutpost.com/2014/sep/5/why-eel-river-disappeared-and-what-it-means-fish/ . This extraordinary event should be distinguished from the earlier disconnection of flows at the bottom of the heavily aggraded Van Duzen River in July of 2014; that reach has been subject to disconnection since it became heavily aggraded. See https://lostcoastoutpost.com/2014/jul/17/drought-makes-van-duzen-river-disappear/
 At p. 178 of Vol II, NMFS’s Coastal Multispecies Recovery Plan states that “Adult Chinook salmon tend to enter the Eel River in early September,” but see also http://www.northcoastweb.com/fishing/rivers/eel/SPOT_EEL.HTM, which states “Chinook start coming into the river in August.”