Aquatic Life / Habitat Assessment Project PAR 991 June 30, 2006

Project Goal u Conduct a comprehensive study to: u Assess aquatic life/habitat improvement alternatives u Develop recommendations for aquatic life/habitat improvements u Prepare a Study Phase Report

Project Overview u Segment 15 channel and flow characteristics have been altered considerably due to: u Floodplain & resource development u Urbanizing hydrology u Water supply activities u Bed and bank stabilization

Project Overview (cont.) u Overall habitat quality is low for indigenous fish species. u Original conclusion based on 1992 mapping of entire segment u Confirmed by 2005 mapping u Aquatic habitat improvements, including u Flow modification u Physical habitat enhancement

Habitat Availability for Target Fish Species Habitat improvements that increase the variety of depth, velocity, substrate and cover regimes will be the most effective for attracting and supporting a diverse fish species assemblage.

Project Approach 1. Identify aquatic habitat baseline conditions 2. Develop aquatic life/habitat improvement alternatives 3. Evaluate alternative improvements 4. Select a preferred alternative 5. Establish an implementation program 6. Obtain MOU Agency concurrence

Biological Literature Review u Native Fish assemblage predominately supported by a harsher, intermittent flow regime driven mostly by abiotic processes u Urbanization has resulted in environmental conditions dominated by lack of seasonal variability of flow and temperature and greater base flow u Segment 15 Fish Community u 17 fish species common in Segment 15; 5 are non- native species u 20 fish species rarely observed or have the potential to be observed; 7 are non-native species

Common Fish Species in the South Platte River * = non-native species

GenusSpeciesCommon Names Propst 1982 Goettl 1982 CDOW 1992 CDM et al 1993 CDM et al 1994b USGS 1995 MWRD Catostomidae Catostomuscatostomuslongnose sucker XXXXXXX Catostomuscommersoniiwhite sucker XXXXXXX Cyprinidae Cyprinuscarpio*common carp XXXXXXX Notropisstramineussand shiner XXXXX X Pimephalespromelasfathead minnow XXXXXXX Rhinichthyscataractaelongnose dace XX XXXX Semolitusatromaculatuscreek chub XX X XX Fundulidae Funduluszebrinusplains killifish XXX X Poeciliidae Gambusiaaffinis*mosquitofish XXXXX Gasterosteidae Culaeainconstansbrook stickleback XXXXXXX Centrarchidae Lepomiscyanellusgreen sunfish XXXXXXX Lepomis humilisorangespotted sfsh XX X Micropterussalmoides*largemouth bass XXXXXXX Pomoxisnigromaculatus*black crappie XXX XXX Percidae EtheostomaexileIowa darter X X X Percaflavescens*yellow perch XX XXX Ictaluridae Ameiurusmelasblack bullhead XXXX X

Rare or Potential Fish Species in the South Platte River * = non-native species

GenusSpeciesCommon NamesPropst 1982 Goettl 1982 CDOW 1992 CDM et al CDM et al. 1994b USGS 1995 MWRD Clupeidae Dorosomacepedianumgizzard shadXX Catostomidae Carpiodescarpioriver carpsuckerXX Cyprinidae Campostomaanomalumcentral stonerollerXX X Carassiusauratus*goldfish XX X Cyprinellalutrensisred shinerXX Hybognathushankinsonibrassy minnowX Hybognathusplacitusplains minnowXX Luxiluscornutuscommon shinerXX X Notropisdorsalisbigmouth shinerXX X Phenacobiusmirabilissuckermouth minnowXX Phoxinuseosnorthern redbelly daceX Fundulidae Fundulussciadicusplains topminnowXX X Centrarchidae Lepomisgibbosus*pumpkinseed X X Lepomismacrochirus*bluegillX X Micropterusdolomieu*smallmouth bass XX Pomoxisannularis*white crappie X X X Percidae Etheostomanigrumjohnny darterXX X X Sandervitreuswalleye X Ictaluridae Ameiurusnebulosus*brown bullheadX Ictaluruspunctatuschannel catfishXX X X

Biological Basis for Habitat Improvements Segment 15 resident fish species – particularly natives – provide the basis for development of habitat improvements

Flow Impacts on Habitat Improvement Alternatives Habitat improvements must be implemented in reaches of Segment 15 that have sufficient existing and future flows.

Segment 15 Water Development Activities Existing and future flow characteristics will affect aquatic habitat u Water rights exchanges u Agricultural water rights acquisition u Development of lined gravel lake storage u Water conservation & efficiency u Future effluent discharges & other return flows u Use of consumable return flows u Chatfield Reservoir Reallocation of flood storage

Future Flow Expectations u Approximately 80 cfs of existing consumable return flows. u Existing consumable return flows will be diverted within Segment 15. u Future low flows, at times, will be less than 1954 due to exchanges and agricultural acquisitions. u Decrease in flows as river travels downstream u Significant reduction downstream of Brighton Ditch. u Subtracting 80 cfs from 2002 calculated flows (dry year) represents a reasonable approximation of future low flows.

Habitat Improvement Options Identified options mimic typical Segment 15 habitat types u Riffles u Pools u Protective cover

Development of Alternatives Site specific based on Habitat Improvement Reaches (HIRs) with 3-tiered approach to evaluation u Tier 1 – Physical implementation u Does the potential exist for appropriate habitat u Retained top 10 HIRs for further evaluation u Tier 2 – Success of implementation based on Channel morphology Infrastructure Ownership Stakeholder cooperation Biological considerations Cost effectiveness Sustainability Regulatory concurrence u Tier 3 – “Deal Breakers” considered

Final Alternative Ranking

Recommended Alternative Reach 9 –Brantner Ditch diversion to Henderson Road u Diverse habitat elements can be easily implemented u Bracketed by reaches that have high quality habitat u Relatively good existing and future flow conditions

Recommended Alternative u 6 backwater pools (11 acres) u 5 riffles u 9 snags u 5,400 feet of spur dikes u 2.5 acres of revegetated banks Proposed improvements include:

Backwater Wetland Pools Pool at Reaeration Structure 3

Spur Dikes South Platte River Spur Dike at Hwy 85

Snags Snag on the Straight River, MN Proposed Snag configurations

Riffles Urban Drainage & Flood Control District Grade Control Structure

Flow Augmentation Through Chatfield Flood Flow Reallocation u Reach 1 would particularly benefit due to existing zero flow conditions. u Reach has relatively good habitat. u Fish sampling has resulted in high populations. A cooperative agreement to maintain minimum stream flows in Segment 15

Calculated Stream Flows at Key Locations March and October 1999 Average Hydrology

Calculated Stream Flows at Key Locations January and April 1995 Above Average Hydrology

Calculated Stream Flows at Key Locations December and August 2002 Below Average Hydrology

Predicted Changes in Average Flow Depth with 80 cfs

Predicted Changes in Average Flow Velocity with 80 cfs

Maximum Water Depth (ft.) Under Various Flow Scenarios 10 cfs30 cfs50 cfs80 cfsLocation ft. US of I-270 Bridge ft. US of MWRD Access Rd ft. US 64 th Ave ft. US UPRR Bridge ft. US Gardener Ditch