Notes on Possible Effects of Flow Depletion on Gualala Fisheries Resources
Quote below is from: Higgins, P.T. 1997. Gualala River Watershed Literature Search and Assimilation. Funded by the Coastal Conservancy under contract to Redwood Coast Land Conservancy. Gualala, CA. 59 pp.
In 1938, the North Gualala Water Company first applied for appropriated rights to surface water in Robinson Gulch and Big Gulch(Sommerstrom,1994). In 1958, the company received an appropriative right to divert water from Fish Rock Creek, and in 1964, the rights to the mainstem North Fork Gualala. The latter right allows for extraction of 2 cfs but calls for by-pass flows of 4 cfs. The California Department of Fish and Game measured the flow of the North Fork in 1988 and found that by-pass flows were not being met (Cox, 1988). John Bowers, manager of the North Fork Water Company, asserted that by-pass flows were indeed being met at the point of extraction (North Coast Institute, 1988). Aggradation in the lower North Fork Gualala River might cause a decrease in surface flow and explain this anomaly.
In 1989, the North Gualala Water Company (NGWC) drilled a well on the terrace of the lower North Fork Gualala River and switched its intake system from surface water to ground water. The company assumed that the water it was drawing was not connected to surface waters and was, therefore, not subject to permitting from the State Water Resources Control Board. A hydro-geologic assessment was conducted for the purpose of establishing whether ground-water extracted from NGWC well was from "a source characterized as a ‘subterranean (underground) stream’ and, therefore, subject to State water rights appropriation rules and regulations or from a source classified as percolating groundwater," and thus not subject to the above noted appropriation rules (Slade, 1992).
The Slade (1992) report concluded that "the Gualala River system and, in particular, the groundwater extracted by North Gualala Water Company Well #4 is under the controlling jurisdiction of the SWRCB and subject to permitting for appropriative rights over the use of groundwater supply within this river." Well #4 was found by the SWRCB to be in violation of licensing and permit conditions (Kessel, 1992). NGWC subsequently applied to the SWRCB for a change in point of diversion (#14853) but several parties have protested the application (Slota, 1996), including the California Department of Fish and Game (Hunter, 1996).
Sommarstrom (1992) noted the current pattern of use by the North Gualala Water Company and projected growth of water needs for the portion of the Gualala River basin in Mendocino County. The NGWC claims a 12,000 acre service area that extends north of the town of Gualala. The number of service connections of the NGWC grew from 671 in 1985 to 847 in 1990(Sommerstrom,1992). The NGWC had 902 hook-ups as of 1995 and was limited to a maximum of 1034 by the California Department of Health Services unless the storage and delivery system were substantially upgraded (Coast Action Group, 1995).
Sommerstrom (1992) projected population growth in coastal Mendocino County from 1.75% to 3% but noted that some areas might experience much higher growth rates: "Gualala, for instance, could become a regional center for the south coastal area of Mendocino County and the north coastal/Sea Ranch area of Sonoma County." Coast Action Group (1994), in comments on the Gualala Municipal Advisory Council proposed General Plan and Local Coastal Plan Amendment, expressed concern over growth and development. They noted potential conflicts with protection of fisheries and with the Mendocino County General Plan.
The Gualala River below the North Fork and the Gualala estuary are the main areas of production for juvenile steelhead, especially those older than one year which are most likely to contribute to adult returns. During the 1976-77 season, the North Fork provided about 35% of the flow in the lower Gualala River (Boccione and Rowser, 1977). The North Fork also contributes cold water that helps to buffer the lower river and estuary from warmer tributary influences. If the North Fork Gualala River flows were depleted, it would likely have a major impact on carrying capacity for steelhead juveniles.
While agricultural water use in the Gualala River watershed may not have been excessive in the past, vineyards are now being developed in some areas. These vineyards may have a direct impact on tributary flow if surface water is used. If wells are drilled in upland areas, and if the aquifer is joined to headwater springs, flows in some tributaries could be affected. EIP Associates (1994a) projected that development of vacation homes or residences could result in use of up to 2.5 cfs for the entire basin.