Future Data Improvements

Instream Spawning and Rearing Habitat

Data Sources: CDFW 1991 (pg. 105 - 107)

Instream spawning and rearing habitat for Fall Run Chinook Salmon and Steelhead in the Mokelumne River is based on data from USFWS’s 1998 instream flow evaluation and EBMUD’s 2016 instream habitat evaluation. The East Bay Municipal Utility Distract (EBMUD) instream spawning and rearing habitat data were provided in a spreadsheet. Together, these evaluations determined relationships between flow and both suitable spawning and rearing habitat for reaches spanning approximately 35 miles of the Mokelumne River.

Combine Instream Spawning and Rearing Habitat Data

The instream spawning and rearing habitat data described above are combined for use in the Decision Support Model (DSM) in the following format. Units are in square feet per 1000 feet.

Header Descriptions: flow_cfs = flow in cubic feet per second, FR_spawn_wua = Fall Run Chinook Spawning wua, FR_fry_wua = Fall Run Chinook Fry wua, FR_juv_wua = Fall Run Chinook Juvenile wua, ST_spawn_wua = Steelhead Spawning wua, watershed = section of stream modeled for CVPIA SDM
flow_cfs FR_spawn_wua FR_fry_wua FR_juv_wua ST_spawn_wua watershed
100 NA 26783.27 29606.59 NA Mokelumne River
105 5662.441 26584.44 29465.08 3969.682 Mokelumne River
140 7016.761 25234.03 28541.24 5167.945 Mokelumne River
180 8240.197 23675.02 27441.99 6462.489 Mokelumne River
200 NA 22880.65 26872.73 NA Mokelumne River

… with 12 more rows

Spawning WUA

The following plot shows the weighted usable spawning area (WUA) rate in square feet per thousand feet for Fall Run Chinook Salmon (FR).

Rearing WUA

The flow:area relationships from USFWS and EBMUD were first expanded using linear interpolation to ensure the relationships for each evaluation reach included the same flows. A single rearing habitat area representing the entire river was then estimated for each flow. Each area was weighted in proportion to the length of the evaluation reach from which the area was originally estimated. The resulting areas were then converted to an area per unit length by dividing the area by the length of the rearing reach mapped by the Scince Integration Team (SIT).

The following plot shows the rearing WUA in square feet per thousand feet for Fall Run Chinook Salmon fry and juvenile.

Floodplain Rearing Habitat

Data Source: CVPIA Annual Progress Report Fiscal Year 2019

The flow : floodplain area relationship for the Mokelumne River is based on high resolution (4 square foot cell size) two-dimensional hydraulic modeling completed by EBMUD in 2017 (Technical Memorandum in preparation by Robyn Bilski at EBMUD). The Mokelumne model was broken into seven reaches (Figure 14) based on the availability of stage-discharge relationships. The extent of this modeling is from River Mile 62.8 to River Mile 64. All area inundated flows less than or equal to 400 cfs were considered as instream. The inundated area per length value from this modeled reach was extrapolated to the entire rearing reach in the Mokelumne River, from Camanche Dam downstream to the point of tidal influence. This flow : floodplain area relationship was used for all salmon and steelhead runs in the Mokelumne River. The following table contains the flow : floodplain area relationships used in the Decision Support Model (DSM).

Header Descriptions: flow_cfs = flow in cubic feet per second, FR_floodplain_acres = Fall Run Chinook floodplain acres, SR_floodplain_acres = Spring Run Chinook floodplain acres, ST_floodplain_acres = Steelhead floodplain acres, watershed = section of stream modeled for CVPIA SDM
flow_cfs FR_floodplain_acres SR_floodplain_acres ST_floodplain_acres watershed
400 0.00 0.00 0.00 Mokelumne River
800 135.50 135.50 135.50 Mokelumne River
900 160.72 160.72 160.72 Mokelumne River
1100 203.68 203.68 203.68 Mokelumne River
1300 239.44 239.44 239.44 Mokelumne River

… with 2 more rows

Floodplain Plot