Difference between revisions of "Salinas Valley Seawater Intrusion"

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(Suggest: rename ('move') this issue to "Salinas Valley Seawater Intrusion")
 
(Suggest: rename ('move') this issue to "Salinas Valley Seawater Intrusion")
  
A [[Watershed Issues|watershed-related issue]] examined by the [http://sep.csumb.edu/wiki/index.php/ENVS_560/L_Watershed_Systems ENVS 560/L Watershed Systems] class at [http://csumb.edu CSUMB].
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A [[Watershed Issues|watershed-related issue]] examined by the [[ENVS 560/L Watershed Systems]] class at [http://csumb.edu CSUMB].
  
 
== Summary ==
 
== Summary ==

Revision as of 07:43, 30 January 2009

(Suggest: rename ('move') this issue to "Salinas Valley Seawater Intrusion")

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

Summary

Seawater intrusion into the Salinas Valley groundwater aquifers has advanced since it was first measured in 1944 (MCWRA, 2009). Currently, elevated salinity level have been recorded less than 1/2 miles from the City of Salinas at the 180 ft. aquifer [1] and is beginning to encroach beyond the city limits of Castroville at the 400 ft aquifer [2]. The saltwater intrusion has continued to move farther inland because continuing overdraft conditions for municipal and agricultural uses.

Location

The Salinas Valley watershed lies within the boundaries of Monterey County, California. Within the boundaries of the Salinas Valley Watershed [3] lies it's groundwater aquifer system which is comprised of four major groundwater aquifers; the Upper Valley, Forebay, East Side, and Pressure 180 [4]. These aquifers create an interconnected underground water system that supplies the bulk of the irrigation and municipal water usage in the Salinas Valley.

Resource/s at stake

Groundwater resources for the Northern end of the Salinas Valley are severely impacted. Although all four groundwater aquifers are hydraulically interconnected, the Pressure aquifer at the front of the Northern end of the watershed is most severely impacted.

Stakeholders

This problem involves a large group of stakeholders with a diverse set of interests. At the southern end of the Salinas Valley aquifer you have the businesses and communities surrounding Lake Nacimiento [5], which rely on the lakes recreational use economically. All the municipalities that lie within the Salinas Valley watershed, including the unincorporated area residents, rely on the aquifers for their drinking water. The Monterey County Water Resources Agency [6]is the governmental agency closest to the actually monitoring and mitigating saltwater intrusion. Other stakeholders are the municipalities of Salinas[7], Castroville[8], Marina[9], which are directly effected. The agricultural community also has a strong vested interest for the aquifer is the primary supply for irrigation water [10].

Laws, policies, & regulations

Currently, groundwater resources are unregulated. The Monterey County Water Resource Agency monitors groundwater quality and levels but has little authority in regulating groundwater extraction. In 1961, Nacimiento Dam was completed to supply irrigation water to the Salinas Valley agricultural community and to recharge the aquifers. Attempts to change structural and operational practices at the dam have meet severe local opposition resulting in several lawsuits.(1)

Systems

Once saltwater intrusion begins, it is irreversible. Our best hope is to stop its current progress and to modify our use of this resource so it will not continue in the future. Saltwater intrusion effects drinking and irrigation water quality, forcing some to search for alternative sources when the salinity of the water exceeds appropriate water quality standards. If salt levels are to high, the water becomes unpalatable for human consumption. Irrigation using water with high levels of salt will damage crops and soil health reducing future use of the land for agriculture.

Science

The Watsonville Water Recycling Project, uses municipal recycled water in irrigation of crops near the front of the saltwater intrusion. This was the result of a large scale study to mitigate saltwater intrusion by creating a fresh water shield between the Monterey Bay Sanctuary and the 150 ft aquifer. Irrigation efficiency studies have been, and are continuing, to help reduce agricultural impact by reducing the quantity of water being extracted.

Tools

Modeling has been used to help understand Salinas Valleys groundwater hydrological system. A model was used in a study of this system and described by April McMillian, for her Senior Thesis at California State University , Monterey Bay [11]. The latest Water Use Summary Report [12] developed by the Monterey County Water Resources Agency is also a good tool in understanding how groundwater is utilized in the Salinas Valley.

Future research

How this system works is understood fairly well. What is missing is the knowledge of exact quantity of water being extracted. If resources were not an issue, metering all agricultural wells to measure the exact quantity of water being extracted would be a good start. This information could be linked to the crop that was irrigated to provide information on specific crop water usage. Analysis of this information would assist agencies such as the University of California Co-Operative Extension, National Resource Conservation District, California Resource Conservation District and others to focus on educational outreach to growers on how to maximize their irrigation efficiency. Remote sensing images could be also be used to aid irrigation efficiency.

References

1. McMillian, April. "Water Table Elevations in the Salinas Valley, California: Animated Visualization using GIS". California State University , Monterey Bay <http://hydro.csumb.edu/Doug/html/salinas_water_table.html> Jan. 2009. 2. Monterey County Water Resources Agency,22 Jan. 2009 <http://www.mcwra.co.monterey.ca.us>. 3. Monterey County Water Resources Agency. Quarterly Ground Water Levels. <http://www.mcwra.co.monterey.ca.us/> March 2006.

Links

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.