Sunday, November 29, 2009
946 Drinking Water Wells in the Urban Midcoast
The Montara-Moss Beach Water Well EIR prepared in 1989 by Kleinfelder states:
Upper Seal Cove Sub-Unit: This sub-unit of the terrace aquifer is located on a coastal bluff west of the Half Moon Bay Airport and south of San Vicente Creek, and is isolated from other hydrologic sub-units. Estimated inflows to the terrace aquifer in this sub-unit are limited largely to precipitation.
Unlike other subunits, the water balance appears to indicate that little or no surplus water is available in the aquifer, that is, that inflows and outflows are in approximate balance. Aquifer outflows may be considered as annual through-flow sustained by annual rainfall, therefore aquifer outflows maybe considered as available ground water. Because the Upper Seal Cove sub-unit is small, and because storage capacity is thought to be small, the aquifer may be susceptible to depletion during dry and critically dry years. The water balance indicates that potential ground water resources in this sub-unit may be quite limited relative to other sub-units in the Montara-Moss Beach study area.
Reliability of Yield: The Montara Heights, Upper Moss Beach, and Upper Seal Cove hydrologic sub-units are areas where difficult well drilling, low yields, and low reliability of yields can be expected. Both the unfavorable hydrogeologic conditions and the relatively large proposed withdrawals should be matters of public concern. Wells constructed in these areas may go dry in areas of deficient recharge, and homes lacking water during dry periods are likely to require supplemental public services.
The 1989 EIR was triggered by the release of 58 sewer connections in the Montara Sanitary District. Since the privately held Citizens Utilities Company was under a moratorium and could not provide water to these parcels, the owners of the lots proposed to drill individual groundwater wells. The County had this EIR prepared to determine whether they could safely allow these wells, and also to assess the cumulative impacts of more than these 58 wells being drilled. Not only did the County allow the 58 wells, but as the Coastal Commission staff report states, over 900 wells have been drilled in the urban midcoast since 1989.
Some wells that were subsequently drilled in Seal Cove to provide water for new houses were dry, so the house could not be built. County Environmental Health would have the specifics. Expect to get contradictory or waffling statements from County Environmental Health.
Upper Seal Cove Sub-Unit: This sub-unit of the terrace aquifer is located on a coastal bluff west of the Half Moon Bay Airport and south of San Vicente Creek, and is isolated from other hydrologic sub-units. Estimated inflows to the terrace aquifer in this sub-unit are limited largely to precipitation.
Unlike other subunits, the water balance appears to indicate that little or no surplus water is available in the aquifer, that is, that inflows and outflows are in approximate balance. Aquifer outflows may be considered as annual through-flow sustained by annual rainfall, therefore aquifer outflows maybe considered as available ground water. Because the Upper Seal Cove sub-unit is small, and because storage capacity is thought to be small, the aquifer may be susceptible to depletion during dry and critically dry years. The water balance indicates that potential ground water resources in this sub-unit may be quite limited relative to other sub-units in the Montara-Moss Beach study area.
Reliability of Yield: The Montara Heights, Upper Moss Beach, and Upper Seal Cove hydrologic sub-units are areas where difficult well drilling, low yields, and low reliability of yields can be expected. Both the unfavorable hydrogeologic conditions and the relatively large proposed withdrawals should be matters of public concern. Wells constructed in these areas may go dry in areas of deficient recharge, and homes lacking water during dry periods are likely to require supplemental public services.
The 1989 EIR was triggered by the release of 58 sewer connections in the Montara Sanitary District. Since the privately held Citizens Utilities Company was under a moratorium and could not provide water to these parcels, the owners of the lots proposed to drill individual groundwater wells. The County had this EIR prepared to determine whether they could safely allow these wells, and also to assess the cumulative impacts of more than these 58 wells being drilled. Not only did the County allow the 58 wells, but as the Coastal Commission staff report states, over 900 wells have been drilled in the urban midcoast since 1989.
Some wells that were subsequently drilled in Seal Cove to provide water for new houses were dry, so the house could not be built. County Environmental Health would have the specifics. Expect to get contradictory or waffling statements from County Environmental Health.
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