ALP 16

o Where is invasive vegetation located now and will test flows increase the spread of
invasive vegetation ?; and
flow losses and travel times in Basin Creek from the dam to the Animas River.
o Where is flow lost and gained?
o How much flow is contributed by side drainages and groundwater?
o What percent of reservoir releases reach the Animas River as surface flow?
o How is flow delivery (surface and groundwater) impacted by the geology, constructed
fill and sediment deposition in the Basin Creek watershed?
o How is flow delivery impacted by the vegetation in Basin Creek, how is vegetation in the
watershed evolving, can future impacts from vegetation evolution be predicted, and
what proactive planning and maintenance actions are needed?
o How can flow management be used to optimally manage vegetation conditions in the
channel?
o Is the current crest gage at Wheeler Crossing sufficient for instrumentation and measure
or should this simple measure be improved or replaced?
3. liming and Fish Screening
Durir g flow testing, reservoir fish should not be transferred to the Animas River. The outlet valve from
the d im was designed to prevent downstream fish and egg passage. Preliminary testing of the
effec iveness of the outlet valve indicated some minnows may survive the passage and 40% of eggs can
be oa ssed.
Becai se small fish may survive passage through the outlet, it is necessary to provide screening of fish
and E Ygs near the outlet discharge during flow testing. A fish screen suitable for up to 200 cfs is being
cons ucted for the outlet by the Reclamation Hydraulics Laboratory. Before Flow Testing can begin, a
scree iing system must be in place at the outlet, sufficient to handle maximum flows (currently
esti ted at 200 cfs). Based on guidance from Raymond Bark and the Durango Area Office, the current
planj to shut down flows in the morning and evening to check entrainment nets.
4. 'test Flow Release
1. Elements of the Flow Test
4.1.1. Overview
The c pening of the valve at the dam is time t =0. There are four time periods outlined as elements of the
flow I est: Groundwater Charging, Surface Water Connectivity, Equilibration, and Measurement. The
duration of Surface Water Connectivity and Equilibrium and unknowns that will be answered during the
flow est. The Groundwater Charge will last for 7 days, and Measurement should take 9 days.
4.1.2. Groundwater Charge
Flow will be released from Ridges Basin Dam at 50cfs for a maximum of 7 days with the aim of charging
the g oundwater with an efficient use of water while minimizing erosion of Upper Basin Creek.
Althc ugh unlikely, periodic monitoring along the channel and at CR213 should be conducted to check if a