Karst and Our Water Supply
Jeff Nolan, Geologist; Jerry Weber, Hydrologist;
John Ricker, Santa Cruz County Water Resources Director
Wednesday, Jan. 8, 2014, 7:30 p.m.
Bonny Doon School Multipurpose Room
Pine Flat Road & Ice Cream Grade
|Our January Program
At our Jan. 8 general meeting, a panel consisting of John Ricker, Jeff Nolan, and Jerry Weber will present what we do and don’t know about Bonny Doon’s karst, how we can find out more, and what we can do to protect it. Please join us for what promises to be a fascinating evening.
17 March—update: the two slide shows from the January meeting are now up on the city water dept. site. Here are the links:
The Incredible Importance of Karst to Our Water Supply
Karst is a landscape controlled by water soluble rocks. Have you wondered about the blocky white boulders going down Felton-Empire Road where the canyon opens out, or the spring-fed stream by the road just below? Do you have a well above Smith Grade or have you noticed disappearing streams below? Have you gone spelunking in Cave Gulch, or simply appreciated the springtime lupine-filled bowl within the poppy field opposite the West Entrance to UCSC? If so, you’ve been looking at a karst landscape.
Hundreds of millions of years ago, the Salinian Terrane, a sliver of land that now stretches from Bodega Head to Ventura, and which lies between the San Andreas Fault and the Rincońada fault miles to the west, lay in a shallow sea similar to the Gulf of Mexico. Sand, mud, and tiny seashells accumulated in thick layers, which eventually hardened into sandstone, mudstone, and limestone respectively. As the Pacific Plate dove under the North American Plate, parts of the plate got deep enough and hot enough to melt portions of the deep sea crust, which rose toward the surface as granite plutons (rock masses), which are now exposed in the Sierra Nevada to the east and to the west at Ben Lomond Mountain. The heat caused the sedimentary rocks to recrystallize as schist and as marble, and then the old Continental Shelf fractured and the Salinian Terrane slid northwest along the San Andreas Fault. Today, after all those eons of erosion and movement, we see the granite to the north on our mountain, schist to the south, and mudstones and sandstones to the west and yet further south under the City of Santa Cruz.
The original seashells were formed in the dim past by plankton from carbonate dissolved in seawater. It takes only the very slight acidity of carbon dioxide dissolved in rain to re-dissolve even the much harder and denser carbonate rocks, limestone and marble, which the seabed became along the fractures of the intervening eons. When exposed on the surface, this chemical weathering gives rise to the paved landscapes of rural Ireland and the spectacular mountainous stone forests of China and Viet Nam.
Why is karst important?
Water flows very very slowly through the minuscule gaps between the grains in granite and schist, and at a snail’s pace through sandstone and mudstone, all of which are impervious to acid. However, when it reaches marble or limestone underground the acid attacks and actively dissolves the carbonate rocks, resulting in chemical erosion along fractures, and carves out caves and underground rivers. These caves are home to scenic wonders such as stalagmites and stalactites. Limestone caves and caverns have long been used by humans. The 30,000 to 40,000-year-old remnants of the first known art are Stone Age paintings in the caves of Europe. More recently, Anheuser-Busch utilized similar caves for natural cold storage of Budweiser when they started in St. Louis.
When karst caves and passages are only buried by a few tens of feet of stone and soil, the caves can collapse, allowing sinkholes to swallow streams and form basins, the typical karst surface landscape. Karst landscapes are characterized by a lack of surface drainage. Streams flow only during the heaviest rainfalls and then stop flowing very quickly after the rainfall stops. Many of these streams simply disappear into dolines, or sinkholes, never reaching a river or the ocean. The drainage system, instead of being above ground, is below ground. UCSC’s Great Meadow is an excellent example of a karst landscape dominated by dolines (closed surface depressions), and the absence of surface drainage.
Most important of all, karst can be both a conduit and reservoir of water. The gaps in karst, instead of being measured in millimeters, as they are in non-soluble rocks, are measured by inches and sometimes even hundreds of feet in size. Once water reaches karst, the filtering that the rocks and soil above provide stops. Karst does not filter and purify the water, so it has a high potential for contamination, which it rapidly transports.
So where does the water go? Eventually it will flow to a point where the limestone terminates against a mass of impervious rock. At these points, springs are formed. The pure drinking water from the springs of Ben Lomond Mountain is depended upon by the people of the San Lorenzo Valley, Davenport and Santa Cruz city, which draws water from Liddell and Reggiardo springs on the North Coast. The endangered Coho salmon of the North Coast and the Steelhead and Coho of the San Lorenzo also rely on the cold, spring-fed streams to spawn.
What we don’t know
The City Water Department has long known of nitrates and clouding in the water coming from Liddell Spring, immediately below the CEMEX quarry. The source of the contamination was never determined: septic systems in Bonny Doon? The old turkey farm between Smith Grade and Bonny Doon Road? Or, most probably, explosive residues from the quarry.
At the time of the last review of CEMEX’s quarry expansion plans in 2009, what did come to light was the fact that Santa Cruz County is one of the few in the US with significant karst resources and no karst protection policy. At that time, the Santa Cruz County Water Advisory Commission, at the urging of Chris Berry, Biologist and Watershed Compliance Manager for Santa Cruz City Water, took up the task of trying to formulate such a policy. The goal is not to promote active mining of the water, i.e. drilling and pumping wells, by local water departments (which would, in any case, face monumental challenges from CEQA, the California Environmental Quality Act), but to protect both the wells of rural residents and the passive use of spring water by fish and city and valley residents.
It is, of course, impossible to develop a policy to protect a resource which is not well understood and difficult to study. Most of what we know is still largely anecdotal and unexplained.
For instance, according to retired UCSC Campus Architect Frank Zwart, when the present Earth Sciences building at UCSC was being built, even though there had been a preliminary geotechnical survey, once the foundation was dug and poured in 1992, the weight of rain water from a winter deluge opened up a sinkhole, requiring further studies and massive amounts of pressure grouting (concrete pours) beneath the building site.
Early in the construction of UCSC, geologist and Earth Sciences lecturer Jerry Weber supervised the drilling of a well into the karst at the intersection of 2 large fractures below the Great Meadow. They hit a large void and the water table at a depth below 100 feet and pumped out a million gallons of water over a week. At the end of the pump test the water table only dropped the water level in the well 2 feet. Even more remarkably, the pumping produced no measurable effect on the flow from the 15 springs at the base of campus and along Spring and High Streets which he monitored. John Ricker, Water Resources Division Director for the County Water Environmental Health Services, conjectures that the karst aquifer under UCSC is comparable, if not larger in size than Loch Lomond reservoir.
Quite recently, consulting geologist Jeff Nolan, who was hired by City Water, with support from the County and San Lorenzo Valley Water District, to map the marble and study the karst within the County, discovered that the outflow of the springs from Ben Lomond Mountain correlates not with that years’ rainfall, as one might expect from such a fast moving aquifer, but rather with the moving average of the most recent 3 years’ rainfall.
2013 in Review—Summaries of the most important stories from the 2013 Highlanders:
The California 6th District Court of Appeal decertifies the Environmental Impact Report for the joint UCSC/City of Santa Cruz applications to LAFCO, the Local Formation Commission, to extend water to supply the planned massive 3 million square foot expansion of the university to its North Campus, in Bonny Doon, thus further delaying any construction.
JoeBen Bevirt of Bonny Doon buys the CEMEX limestone quarry property and several smaller CEMEX properties along Smith Grade. With the purchase of the CEMEX Redwoods property by a consortium of conservation agencies, this virtually ends CEMEX’s presence in Bonny Doon, although the company is still obligated to implement its reclamation plan for the quarry itself.
The California 6th District Court of Appeal reverses a local Superior Court denial of a suit by local environmental organizations, including the RBDA, seeking to force public hearings on the transfer of the Coast Dairies property agricultural parcels and to strengthen restrictions on the use of motorized vehicles on the part of the property to be opened to the public.
Beauregard Vineyards applies for a permit to expand wine production, host public community-oriented events, and convert a part of its wine production building to a dwelling. The proposal generates heated controversy between supporters and detractors.
The Land Trust’s Bryan Largay reveals to a large audience at the September RBDA meeting all the details of the process to open CEMEX Redwoods to the public. Concerns are voiced about the impact on Bonny Doon, especially at the access points.
The local Superior Court orders UCSC and the City to revise the EIR for the water service expansion to the North Campus.
Bonny Doon’s Needs ID’d
In November the RBDA Board learned from the Heartland group that financial pressures were forcing them to sell their 5-year lease/option to buy the Bonny Doon Village Airport property on Empire Grade. To find out if there was some important community need that the property might be used for, we arranged a meeting of leaders from the Fire Team, the school board, CAL FIRE and Supervisor Neal Coonerty.
The group suggested that a public meeting be organized to poll the community, and we agreed to facilitate it. In the week preceding the Dec. 10 meeting the Heartland group was negotiating with the airport property’s owners, the Hoogners, to sell back the lease/option. Therefore we decided to expand the scope of the meeting to a discussion of the most important unfilled needs of the community, and to initiate a process for people to organize to try to fill any or all of those needs, but not to focus on the airport property itself.
About 40 people came to the meeting, and they named 16 things they felt were important to have in Bonny Doon. At the conclusion there was a straw poll to determine how popular each idea was, and a signup sheet for people to connect with each other if they want to work on filling any of the needs suggested.
The most pressing need, supported by 36 people, was to have a piece of land that remains available as a staging area in a community emergency or disaster, such as an earthquake or wildfire. Related to that, 32 people wanted there to be more Dooners with CERT training to provide immediate aid to people in such a disaster. If you are interested in that, go to CERT@bonnydoonfire.org for more information.)
Between 21 and 24 people supported the ideas of: a Bonny Doon based service provider network for seniors to help them continue living in their homes (click on this link to learn more about what that involves); a local farmers market; a community center; and footpaths connecting parts of Bonny Doon.
Garnering 18 or 19 votes were better mobile phone service, a Bonny Doon based nurse practitioner, and a place for families and children to learn about nature and the environment. Other, less popular ideas included a solar charging station for electric cars, a soccer field and a community garden. There were 14 people who felt it was important to keep Bonny Doon just as it is, though it was clear that they liked the idea of an available emergency staging area and CERT training.
If you are interested in exploring ways to bring any of these suggestions to fruition, email us at email@example.com and we will send you the contact list.
A Monumental Moment for Coast Dairies?
There’s a new wrinkle in the already convoluted 13-year old saga of trying to open Coast Dairies to the public. The Santa Cruz Sentinel has reported that some conservation groups are quietly (until now, anyway) trying to promote the idea of attempting to get the federal government to make the 6,000 acre property a National Monument.
Whether that would offer more protection for the land, or provide more funds to support it, is open to debate. Big Creek Lumber has circulated a letter in opposition, fearing a loss of land to log, and has garnered Supervisor Neal Coonerty’s support.
The Trust for Public Land, according to the Sentinel, is pushing the idea. For years it has been trying to divest itself of the burden of taking care of the property, and desperately wants to transfer it to the federal
Bureau of Land Management. The BLM already manages many properties under several different legal categories, including Fort Ord, which is a National Monument. There are very strong deed restrictions already on activities on Coast Dairies. What is to be gained by it becoming a National Monument? Would that serve to attract a lot more visitors, which could add to the impacts on Bonny Doon?
Supes Talking Pot
Trying to make some sense of our Alice-in-Wonderland laws regulating marijuana, and preparing for the day when recreational pot use is legalized, the Board of Supervisors is considering various changes to the regulations regarding marijuana cultivation. The attempt has raised concerns of residents of rural areas, including some Bonny Dooners who met recently with Supervisor Neal Coonerty.
They report that Coonerty reassured them that the supervisors have agreed that legal pot grows (under California’s medical mariijuana laws) will be prohibited on parcels of fewer than 5 acres, which should assuage the concerns of Bonny Doon’s denser neighborhoods, like Pine Ridge.
The supervisors will be talking more, and seeking public feedback, at their January meetings. Go to the supervisors’ website for the agendas.
Time to Renew RBDA Memberships
This is the time of the year when we catch up and celebrate with family and friends, and of course, included in that is renewing your RBDA membership. All annual memberships expire on January 31 each year, so unless you signed up for multiple years, please fill out the form on page 3 and mail it in with the appropriate dues payment for your address.
The overwhelming amount of dues revenues pays for the printing and mailing of The Highlander to all households with mailboxes in the Bonny Doon Planning District. If you are a member but don’t have a mailbox in Bonny Doon, email us at firstname.lastname@example.org and we will send you an electronic copy. If you don’t have an Internet connection, write to us via snail mail and give us your post office box or other address and we’ll send a paper copy of the newsletter.
Other RBDA expenses go for rental of the Bonny Doon School Multi-purpose room for meetings, and the required liability insurance, occasional replacement of equipment like the projector and sound system we use for meetings, and some fees for lawsuits (the attorneys work pro bono) that we occasionally join in on.
Board Elections at January 8 Meeting
The 3 RBDA Board officers whose terms expire on Jan. 8 were nominated for reelection at the Nov. 13 RBDA general meeting. They are Joe Christy, Ted Benhari and Lad Wallace. No other nominations were made. The RBDA Bylaws require that in order to run for the Board a candidate must be nominated at the November meeting.
On a related matter, our chairman, Jacob Pollock, informed us in December that for personal reasons he has had to move from Bonny Doon, and therefore must resign from the Board. According to the Bylaws, since we learned that after the November nominating meeting, the Board must appoint someone to fill out the remaining year of Jacob’s term.
We are very sorry to be losing Jacob, whose expertise in environmental matters was invaluable during the past 3 years. He also played a significant role in our successful effort to get the County to revise the Large Dwelling Ordinance, reducing the square footage of a proposed house downward from 7,000 to 5,000 square feet, and clearing up a lot of the confusing language regarding habitable versus uninhabitable space.
Support the RBDA by renewing your membership now: all 1-year memberships expire on January 31st.
Ideas for RBDA Meeting Topics
We are always open to suggestions for interesting programs and speakers at our bimonthly (except July) RBDA public meetings.
What are you interested in? Local flora and fauna, gardening, environmental and political issues, Bonny Doon history or geology, public safety?
What were some of your favorite speakers or presentations at past RBDA meetings?
Were there any that you would like us to repeat?
Please email us with your ideas and comments at email@example.com.
California Oaks - photo by Ted Benhari
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