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The 24.5-ac. seasonal pond creation was based on a statistical assessment of available historical data on rainfall, evaporation and evapotranspiration for the project area. However, since Livermore receives on average only 14 inches of annual rainfall, William Vandivere, first as Head of the HT Harvey & Associates Hydrology Division (1988-94) and then later as CH Principal, conducted additional field infiltration testing as well as event gaging of rainfall and runoff in order to provide more site-specific data upon which the water balance studies were based. The ponds were constructed in 2004 and have achieved the design ponding and amphibian habitat characteristics.
One of the Northern Drainage restorations included the conversion of an on-stream seasonal pond to an off-stream pond. The existing pond had essentially dammed the channel, and the lack of a proper outlet structure resulted in severe erosion of the pond embankment. The CH restoration design included a channel re-alignment and a side-channel overflow weir, in addition to rehabilitation of the reconfigured pond embankment. This ensured the stability of the rehabilitated pond, while providing it with some additional inflow during periods of elevated streamflow. The four channel reaches restored on the Northern Drainage comprised a mix of step-pool and rapid-pool morphologies.
CH also developed restoration designs for two additional channel reaches along Tassajara Creek, a major regional stream corridor, both of which were constructed in the summer of 2004. One of reaches featured the restoration of consecutive channel meanders along a degraded, heavily grazed portion of the creek using native material revetments. The other reach featured a step-pool construction for local enhancement of CRLF habitat. Both of the restoration reaches were revegetated with native riparian species and were fenced to exclude cattle access.
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Northern Drainage - Kobold Reach Restoration: Pre-project condition-severely incised and unstable channel filled with concrete rubble and other debris
Northern Drainage - Kobold Reach Restoration: Year 2 - Upstream view of rapid-pool structure with log weir
Tassajara Creek - Construction of native material revetment along outside meander radius (2003)
Lin Livermore seasonal wetland ponds: Year 4 condition, fed by incident winter rainfall and watershed runoff
DATE: Completed November 2006
LOCATION: Dublin, CA
CLIENT: H.T. Harvey & Associates
LINK: http://www.harveyecology.com/
GOALS: Habitat restoration, amphibian breeding habitat, channel stabilization, riparian vegetation establishment
