Morrison Creek and Parsons Creek Groundwater Study and Revegetation Projects
La Ribera and Haiku Ranch border the Russian River and Morrison Creek. Morrison Creek is highly affected by the incision in the Russian River (see King Ranch Enhancement Project) and at the time the Farm Conservation Plan was completed in 2002, supported very little riparian cover.
Prior to attempting any planting, shallow groundwater levels beneath Morrison Creek downstream of the Old River Rd. Bridge and Parsons Creek above and below the bridge were measured using monitoring wells. Groundwater levels in both creeks dropped 6-8 feet in 30 days once the water level in the Russian River was reduced by the dam operations in spring. Since the channel of the Russian River represents the lowest point in the valley, the groundwater in Morrison and Parsons Creeks drains to this point. The 20-25 feet of channel incision in the Russian River, combined with the reduction in releases from Coyote Dam, causes the groundwater beneath these creeks to drain quickly, de-watering the riparian zone. Therefore, traditional willow planting methods into the surface of the creek floodplain would not be successful because the willow roots cannot keep up with the rapid drop in groundwater levels.
Deep trenching of willow was used at both creeks. In February 2001, a backhoe cut a 6-8 foot deep trench on the floodplain adjacent to the low-flow channel of Morrison Creek. 10 ft. dormant willow poles were placed in the trench; then the trench was refilled. The willow sprouted roots from the bottom of the trench and chased the declining groundwater from this deeper location. All of the willow poles on both creeks leafed out. On Parson’s Creek the willows closest to the Russian River did not survive while those upstream did survive. On Morrison Creek most of the willows survived but were extremely water stressed during the summer. Planting in deep (8 foot or greater) trenches may increase the survival in some areas; however it may not be possible to revegetate some sites near the Russian River channel.