CalAm Use of Carmel River Groundwater Basin

A watershed-related issue examined by the ENVS 560/L Watershed Systems class at CSUMB.

Summary

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Location

• Carmel Watershed
• Carmel River Watershed: Map of Elevation
• The Carmel Watershed is 255 square miles and is located in Monterey County, CA. The region is bounded by the Santa Lucia mountain range to the southwest and the Sierra de Salinas mountains to the Northeast.

Resource/s at stake

The resource of concern in this watershed-related issue is the water captured by the Carmel Watershed. The surface water supplies were originally thought to be a separate resource from the groundwater, however in 1995 the SWRCB ruled that the groundwater wells were subject to SWRCB jurisdiction .

Another important resource is the Seaside groundwater basin. This basin is the only other water source CalAm is using to supply the Monterey Peninsula. It has been determined that this basin has a safe yield of 3,000 AF/year, but is being drafted at a rate of 5,600 AF/year. It is agreed that the Seaside Basin is being overdrafted.

A recent adjudication decision in 2008 limited the amount of water to be taken out of the Carmel River to 11,285 AF/year and out of the Seaside Basin to 3,504 AF/year.

Many are concerned about overdrafting the Carmel River because it is home to a large Steelhead population. Steelhead in the South-Central California region are a federally threatened species, and are protected under the federal Endangered Species Act. A major decrease in surface water in the Carmel River may lead to a decrease in Steelhead habitat, and a reduction in the Steelhead population.

Stakeholders

• California American Water
  • The agency responsible for supplying the Monterey Peninsula with water
• County of Monterey
  • Private users of CalAm water, including households and farmers
• Steelhead and those concerned with their well being
  • For example the Pacific Rivers Council
• Private Well owners
  • Individuals or communities who do not use CalAm water, but are affected by water rationing

Laws, policies, & regulations

Between 1987 and 1991 the State Water Resources Control Board (SWRCB) received formal complaints from four stakeholder organizations within the Carmel Valley: the Carmel River Steelhead Association, the Sierra Club, the Residents Water Committee, and the California Department of Parks and Recreation. Complaints alleged that pumping of the Carmel River Aquifer by Cal-Am:

• Caused observable recession of the Carmel River riparian zone
• Was Destroying habitat for the then threatened post 1998 endangered Steelhead Salmon
• Violated the public trust doctrine – stating that the harvesting of a public resource (Carmel River water) must not interfere with the ability of the public to utilize that resource.

In 1995 the SWRCB upheld the allegations of the Carmel River stakeholder groups, determining that Cal-Am had no legal right to 10,730 acre-feet of the 14,000 drafted annually and passed Order WR 95-10. This Cease and Desist order included a mitigation plan requiring that Cal-Am reduce the amount pumped from the Carmel River via a series of options. These options included:

• Appropriating/purchasing legal rights to the water in overdraft
• Greater reliance on the nearby Seaside Aquifer
• Building of a new dam and/or exploration of alternative and renewable sources of fresh water such as desalination and waste water treatment.

Systems

• Seventy five percent of the Monterey Peninsula's water supply is pumped from the Carmel River alluvial aquifer . If there is not equivalent recharge to replenish the pumped water, the water table will decrease. Irrigation along the channel of the Carmel river currently mitigates vegetation mortality and bank erosion caused by a depressed water table .
• Two endangered species, red-legged frogs (Rana aurora) and steelhead trout (Oncorhynchus mykiss), depend on the Carmel River for habitat.
• The Carmel River needs a sufficient supply of water to maintain a healthy riparian and river ecosystems.

Science

• Physical and Hydrologic Assessment of the Carmel River Watershed California
• Carmel Valley Groundwater Basin
• Watershed Assessment and Action Plan of the Carmel River Watershed California

Tools

Studying groundwater is difficult at best. However, hydrogeologists working in watersheds can use various clues in local environments to model groundwater using the water cycle. The City of Olympia, WA, in their planning for a series of groundwater wells (City of Olympia Groundwater) have identified model inputs that hydrogeologists would want to use to analytically quantify groundwater in a watershed:

• Information from well logs, groundwater levels and the rate at which ground water travels.
• Aquifer characteristics. Namely the permeability, thickness, location, extent and the boundaries.
• Volume of water exiting the streams.
• Volume of water leaving springs.
• Volume of water leaving tributaries.
• Groundwater recharge-in the forms of precipitation, and surface runoff.
• Finally, the quantity of water being pumped under various scenarios.

Future research

Future research, especially in the Carmel watershed, should be focused on capacity issues of the carmel aquifer. We need to better quantify the amount of water that can be extracted without the risk of land subsidence causing permanent decrease in aquifer storage capacity . Another major issue for the carmel river groundwater basin is salt water intrusion. While a granite sill currently protects the aquifer from significant salt water intrusion (as is the current problem in the Salinas Valley (salt water intrusion) ), questions remain as to how far we can drain the aquifer before witnessing significant losses of the fresh water portion of the aquifer. Both these issues require immediate attention to avoid serious, irreversible consequences that will inedibility constrain our ability to sustain the life style we are accustomed to on the peninsula.

Master's candidates in the Coastal and Watershed and Environmental Policy program at California State University of Monterey Bay could pursue either of the above mentioned future research. Both will require significant modeling of the groundwater aquifer combined with visualizations for policy purposes. With unlimited funding, one could dig measuring wells throughout the carmel watershed to develop a 3D model of the entire aquifer--similar to what the Salinas Valley currently possesses today.

Disclaimer

This page may contain student work completed as part of assigned coursework. It may not be accurate. It does not necessary reflect the opinion or policy of CSUMB, its staff, or students.