San Diego Coastkeeper


Chollas and Paleta Creek

Chollas and Paleta Creek Watershed Monitoring Project

Segments of both the Chollas and Paleta Creeks are listed as CWA 303(d) impaired waterbodies due to effects from the following pollutant stressors: Bacteria Indicators, Cadmium, Copper, Zinc, Lead, and Toxicity. In addition, the estuary portions of these creeks are also regarded as Toxic Hot Spots within San Diego Bay (BPTCP 1996) and listed for degraded benthic communities and sediment toxicity on the CWA 303(d) impaired waterbodies. The Chollas and Paleta Creek Watershed Monitoring Project was implemented to encourage citizen participation and provide reliable data that would support on-going TMDL efforts as well as assist in the determination of the necessary pollution prevention measures to be implemented in the Chollas and Paleta Creek watersheds.

To complete this project the San Diego Coastkeeper (formerly Baykeeper) worked closely with its grant partners and regional stakeholders to: conduct outreach and education and produce and distribute thousands of copies of bilingual (English and Spanish) watershed pollution prevention educational materials, train nearly 100 volunteers, and conduct 12 monthly citizen watershed and 5 storm monitoring events. In addition, Coastkeeper worked closely with project partner Southwestern College to successfully develop local capacity to analyze water samples for the organophosphate pesticide Diazinon.

Following is a summary of the pollution issues encountered through the course of this project, as submitted to the RWQCB at the completion of this project in January 2006:

 
Parameter Number of Exceedances Recorded Threshold Screening Values* Issues Encountered Recommendations
Temperature NA No numerical standard available for Hydrologic Unit (908.00) Relatively few instances where temperature was greater than 27 degrees Centigrade were encountered. None
pH 2 - Greater than 6.5 and less than 9.0 - Changes should not exceed 0.5 units Very few instances of elevated pH were encountered and variances for those data were large. None
Dissolved Oxygen 29 - No less than 5.0-mg/l - Annual mean dissolved oxygen concentration shall not be less than 7 mg/l more than 10% of the time A substantial amount of exceedances were encountered. With the majority occurring at two sites. Continue monitoring and tracking potential illegal discharges at sites CCW60 and PCW30.
Conductivity NA No numerical standard available for Hydrologic Unit (908.00) A high number of high conductivity values (>1000 uS/cm) were detected, the bulk of which were concentrated at two sites. Continue watershed-wide monitoring and tracking potential illegal discharges at sites CCW50 and CCW60.
Salinity No numerical standard available for Hydrologic Unit (908.00) One instance of elevated salinity was encountered and represents an outlier in the dataset. None
Turbidity 54 - 20 NTU - Maximum allowable turbidity increase over natural level is 20% A substantial number of turbidity exceedances were detected, the bulk of which were concentrated in the Paleta Creek watershed. High turbidity values in the estuary part of the Paleta Creek watershed are believed to be associated with algal blooms, while elevated values at sites above the tidal prism are likely to also be related to suspended solids and erosion. The later is supported by field observations of unstable creek banks and substantial deposits of sediment in the channelized segments of the creek. It is recommended that future work in this area focus on quantifying sediment loading and erosion in the watershed.
Nitrate 29 1.0 mg/L (from Basin Plan) 23 of the 29 exceedances occur at one site in the Chollas Creek. Continue monitoring and tracking potential illegal discharges at site CCW60.
Lead 0 Freshwater criterion maximum concentration (CMC) and criterion continuous concentration (CCC) for Pb are 65-ug/l and 2.5-ug/l, respectively. No exceedances were observed. None
Copper 2 Freshwater CMC and CCC for Cu are 13-ug/l and 9.0-ug/l, respectively Only two exceedances of CMC were detected following a storm event. None
Cadmium 0 MCL 0.005 mg/L (from Basin Plan) No exceedances were observed. None
Zinc 2 Freshwater CMC and CCC for Zn are 120-ug/l and 120-ug/l, respectively. Only two exceedances of CMC were detected following a storm event. None
Diazinon 5 All levels recorded in samples were above the TMDL target level of 0.05-ug/l. Continue monitoring in organo-phosphate pesticide levels in watershed and track Malathion inputs. Also continue bilingual IPM outreach and education.
Malathion 7 All levels recorded in samples were above 0.05-ug/l. Continue monitoring in organo-phosphate pesticide levels in watershed and track Malathion inputs. Also continue bilingual IPM outreach and education.